Culturally appropriate, evidence-based, personalized dietary advice to improve the nutritional status of track and field athletes: a randomized controlled trial

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However, Sri Lankan track and field athletes often fall short of dietary recommendations due to the lack of personalized nutrition guidance. This study evaluated the effectiveness of culturally appropriate, evidence-based, personalized dietary advice on the nutritional status of these athletes. Methods: This 16-week parallel-group randomized controlled trial included 30 national-level track and field athletes (15 in the intervention group [IG], 15 in the control group [CG]). The IG received personalized dietary prescriptions based on detailed nutritional assessments, while the CG received no advice. Outcomes included dietary intake, assessed via seven-day food diaries, and biochemical parameters measured using standard techniques. Results: Twenty-seven athletes (IG: 13, CG: 14) completed the study. The IG showed significant increases in energy intake (Pre: 2766.0 ± 494.0 kcal, Post: 3972.9 ± 934.4 kcal, Change: +1206.9 kcal; p = 0.007) compared to the CG (Pre: 2733.7 ± 635.5 kcal, Post: 2676.5 ± 319.2 kcal, Change: -57.2 kcal; p = 0.739; p for IG vs. CG = 0.004). Protein intake also improved significantly in the IG (Pre: 95.56 ± 30.2 g, Post: 116.81 ± 41.8 g, Change: +21.25 g; p = 0.003) versus the CG (Pre: 94.54 ± 32.8 g, Post: 84.24 ± 16.4 g, Change: -10.30 g; p = 0.162; p for IG vs. CG = 0.001). The IG exhibited improved vitamin and mineral intakes, and serum vitamin D levels in the IG increased significantly (Pre: 30.55 ± 10.2 ng/ml, Post: 42.02 ± 9.6 ng/ml; Change: +11.47 ± 0.6 ng/ml; p < 0.001), while the CG showed no change. Serum ferritin levels also increased in the IG (Pre: 44.76 ± 29.3 ng/ml, Post: 51.54 ± 28.4 ng/ml, Change: +6.78 ± 0.9 ng/ml; p < 0.001), along with positive changes in haemoglobin and other haematological parameters. Conclusions: A culturally appropriate, personalized dietary prescription significantly improved the nutritional status among Sri Lankan track and field athletes. Dietary intake Personalized nutrition Track and field Nutritional status Sri Lanka Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Optimal nutrition is crucial for the provision of energy and nutrients for sports activities, facilitating post-exercise recovery, enhancing sports performance, and promoting overall well-being [ 1 ]. Elite athletes often require more energy, protein, and certain micronutrients than their non-athletic counterparts due to the heightened physical demands of intense training. The daily requirements for energy, carbohydrates, and protein are significantly higher in athletes than in non-athletes, given the increased physical exertion associated with their training and/or larger body size [ 2 ]. For example, throwers, who typically have a larger body mass and engage in rigorous training sessions lasting 1.5 to 4 hours, may have additional caloric needs [ 3 ]. These sessions deplete glycogen stores significantly, and if these stores are not replenished during or after exercise, subsequent performance can be compromised, ultimately reducing overall athletic performance [ 3 ]. Additionally, adult endurance athletes often undergo training programs involving 500 to 1,000 hours per year or running distances exceeding 150 km per week, leading to significant energy expenditure [ 3 ]. While the general population requires approximately 0.8 grams of protein per kilogram of body mass per day (g/kg/day), athletes need between 1.2 to 2.0 g/kg/day, depending on whether they are engaged in aerobic or resistance exercise, with the higher end of the range being more suitable for resistance training [ 4 ]. Additionally, protein needs increase in specific circumstances, such as during periods of intensified training or injury recovery [ 5 ]. For optimal metabolic adaptation, and to support muscle protein synthesis—a key marker of repair, growth, and adaptation—athletes should consume 0.25 to 0.40 g/kg of protein per meal [ 6 ]. This helps in preserving lean body mass, which is crucial for athletic performance [ 7 ]. Dietary fat is also an essential component of an athlete's training diet, with general nutrition guidelines emphasizing the importance of the type of fat consumed. Athletes are encouraged to consume more omega-3 polyunsaturated fatty acids while reducing intake of saturated and trans fats [ 8 ]. For endurance athletes, excessive fat restriction is not recommended, as it can lead to insufficient energy intake, resulting in fatigue, poor performance, and an increased risk of illness or injury [ 8 ]. A fat intake of approximately 35% of total calories is suggested to ensure adequate caloric intake, support intramuscular triglyceride super-compensation, and allow for sufficient carbohydrate intake to replenish glycogen stores [ 8 ]. In this context, the carbohydrate and protein intake of some athletes may be inadequate to meet the demands of athletic performance, and calcium intake may fall below the levels recommended for maintaining bone health [ 9 ]. A recent review found that master athletes participating in world athletics championship competitions generally do not consume sufficient protein, carbohydrates, and various micronutrients to support optimal performance, as determined by 24-hour dietary recalls [ 9 ]. In a similar study involving sprint athletes over three years, consistently low intakes of iron were observed in girls, and both sexes showed low intake of calcium, vitamin E, and B 2 , while sodium intake exceeded the upper reference limit [ 10 ]. Several sports nutrition interventions, including education, counselling, and dietary modifications, have shown positive effects on athletes' nutritional status. A randomized controlled trial demonstrated that an eight-week nutrition education program combined with controlled dietary modifications significantly reduced energy deficits, improving daily calorie intake (97% of needs) and protein intake (88% of recommendations). Athletes in the intervention group also exhibited increased intake of key vitamins (A, B 9 , B 12 , C, and E) and minerals (calcium, iron, zinc, and selenium), highlighting the benefits of structured nutritional strategies [ 11 ]. In addition to nutritional consultation interventions, another study was conducted on football players to examine the impact of vitamin D supplementation on training adaptations [ 12 ]. The findings indicated significant improvements in power-related metrics, such as vertical jumps (squat jump, countermovement jump), following interval training with a daily dose of 5,000 IU of vitamin D for 8 weeks. In a parallel, randomized, double-blind study on iron supplementation, iron-deficient but non-anaemic athletes were given 30 mg of elemental iron as ferrous sulphate daily for six weeks [ 13 ]. This regimen significantly raised serum ferritin levels compared to the placebo group (P = 0.01). Similarly, another trial reported that 7 to 8 months of multivitamin/mineral supplementation enhanced the blood nutritional status of certain vitamins in athletes from various sports, including basketball, gymnastics, rowing, and swimming [ 14 ]. Although there is no nationally published data on the dietary habits of athletes in Sri Lanka, a study on the nutritional intake of undergraduate athletes revealed that they regularly do not consume sufficient energy, proteins, and micronutrients [ 15 ]. Therefore, this randomized controlled trial aimed to assess the effectiveness of a culturally tailored, evidence-based, personalized sports dietary advice in improving the nutritional status of elite-level track and field athletes in Sri Lanka. Methods The CONSORT 2010 statement guidelines regarding randomized trials (www.consort-statement.org) were followed for this RCT [16] and the corresponding checklist is provided in Supplementary Material 1. Trial design This parallel-group randomized controlled trial evaluated the impact of a culturally tailored, evidence-based, personalized sports dietary advice on the nutritional status of track and field athletes in Sri Lanka over 16 weeks. Conducted at the Department of Physiology, Faculty of Medicine, University of Colombo, the study adhered to ethical guidelines outlined in the Helsinki Declaration. Participants provided written informed consent with the option to withdraw or continue follow-up without affecting their clinical care. Ethical approval was obtained from the Institutional Ethical Review Committee, Faculty of Medicine, University of Peradeniya, Sri Lanka (2023/EC/71). The trial is registered with the Sri Lanka Clinical Trials Registry (SLCTR/2024/013) and has a Universal Trial Number (UTN): U1111-1304-8890. The CONSORT diagram (Fig. 1) illustrates the flow of this RCT. Participants Eligible participants included elite track and field athletes of both genders. Potential participants were recruited through contacts from coaches, fellow athletes, and open advertisements in social media groups, targeting national-level athletes. Participants were screened two weeks prior to the intervention and were required to provide verbal and written informed consent. Intervention The intervention comprised a culturally tailored, personalized dietary prescription provided by the principal investigator (RJ), designed to meet the individual energy, macronutrient, and micronutrient needs of each athlete. This prescription was based on a comprehensive assessment of dietary intake, body composition, physical training load, and biochemical parameters. To ensure effective guidance, the intervention included three structured sessions delivered at week 0, week 4, and week 8, each lasting approximately 15–20 minutes. Ongoing support and advice were provided via WhatsApp throughout the intervention period, ensuring the adherence. I. Personalization and cultural appropriateness Athletes were guided to achieve an appropriate energy balance tailored to their individual training loads and body composition. Energy requirements were estimated using practical methods, taking into account contextual constraints. Additional energy supplements were prescribed for those with significant energy deficits, while athletes with high adiposity or excessive energy intake received culturally sensitive dietary advice to manage calorie intake effectively. II. Macronutrient guidelines Athletes were advised to adhere to current carbohydrate intake guidelines, with culturally specific recommendations provided for carbohydrate-rich foods. Protein needs were calculated as 1.2–1.6 g/kg body weight daily, distributed across four protein-rich meals, with 0.3–0.4 g/kg body weight per meal. Recommendations included culturally common protein sources, and whey protein supplements were introduced when dietary intake was insufficient. Advice focused on reducing saturated fats from foods like coconut oil and encouraging the use of healthier unsaturated fats, such as extra virgin olive oil and gingelly oil. Omega-3 fish oil supplementation was recommended for participants with inadequate fish consumption. III. Micronutrient optimization For athletes with clinically confirmed deficiencies, tailored supplementation protocols were implemented. For instance, Vitamin D insufficiency was treated with doses ranging from 1,000 IU daily to 60,000 IU weekly based on blood levels. Iron supplementation was guided by serum ferritin and haemoglobin levels, with additional multivitamin, calcium, and mineral supplements prescribed as necessary. A balanced intake of grains, fruits, vegetables, nuts, and legumes was encouraged. However, high-fibre foods were restricted during pre-training and competitive periods to avoid gastrointestinal discomfort. Intervention group The intervention group (n = 15) engaged in one-on-one consultations with the principal investigator, receiving comprehensive nutrition advice which includes dietary practices and prescription of micronutrients and sports supplements. Control group The control group (n = 15) did not receive any intervention but was followed throughout the study. After the intervention period, participants in the control group were provided with basic nutritional advice. Outcomes Dietary assessment The nutritional status of the athletes was assessed both before the intervention (in the two weeks lead in before the intervention) and after the intervention (at the end of the 16th week) using seven-day food diaries, with food portions and type of food consumed analysed to assess diet quality. The total intake over seven days was averaged and reported as pre- and post-intervention values. Participants were given written and verbal instructions on how to complete the seven-day food records in a provided booklet. The energy content of each food component was calculated using standard energy values for portion sizes. Daily energy intake macro- and micronutrient intake was performed using Nutri-Survey Software modified with Sri Lankan food composition data. Biochemical measurements A full blood count (FBC) was analyzed using the SYSMEX XE-2100 Haematology Automated Analyzer (Block Scientific Inc., United States) to assess packed cell volume (PCV), Haemoglobin, mean corpuscular haemoglobin concentration (MCHC), mean corpuscular haemoglobin (MCH), and mean corpuscular volume (MCV). Additionally, serum vitamin D3 levels were assessed using the MAGLUMI 2000 analyzer through a Competitive Chemiluminescence Immunoassay (CLIA) (Snibe; Shenzhen, P.R. China), which quantitatively measures the sum of both 25-(OH) vitamin D3 (cholecalciferol) and 25-(OH) vitamin D2 (ergocalciferol) in the specimen. Serum Total 25-OH Vitamin D categories were defined as Sufficiency: 30–100 ng/mL, and Deficiency: below 30 ng/mL. Serum ferritin levels were measured using the Cobas e601 device with ECLIA technology (Roche Diagnostics International AG, Rotkreuz, Switzerland). All biochemical assessments were conducted at an accredited laboratory (Nawaloka Metropolis Laboratory, Nawaloka Hospital PLC), following standard procedures. Details regarding the sample size calculation, randomization procedures, and blinding protocols have been published elsewhere [17]. Statistical methods Descriptive statistics were employed to summarize participant characteristics. Independent sample t-tests were used to compare baseline and post-intervention characteristics between groups, while paired t-tests assessed within-group changes for normally distributed continuous variables. The Chi-square test was applied to evaluate improvements in categorical variables, such as Vitamin D levels, before and after the intervention within each group (IG and CG). In all the statistical tests, a p-value of < 0.05 was considered significant. Results Among the 30 participants initially enrolled in the study, 13 from the IG and 14 from the CG completed this intervention (Figure 1). INSERT FIGURE 1 ABOUT HERE The results presented here are based on the 27 participants who completed the study, following the per-protocol analysis approach. The IG had an average age of 23.4 ± 2.8 years, comprising 8 males and 5 females. In comparison, the CG had a mean age of 21.9 ± 3.9 years, with 9 males and 5 females. The average duration of sports experience was 7.15 ± 3.60 years for the IG and 5.92 ± 3.73 years for the CG (p = 0.394). Regarding performance levels, 38% of IG participants and 36% of CG participants were categorized as elite athletes, while 62% of the IG and 64% of the CG were classified as highly trained athletes. The participants competed in four track and field disciplines: each group had one sprinter, the IG had seven middle-distance runners and three long-distance runners, while the CG had 10 and two, respectively, and the IG had two jumpers, whereas the CG had one. Following this 16-week evidence-based sports nutrition intervention, significant improvements were observed in energy intake and macro and micronutrient parameters for the IG compared to the CG (Table 1). During the intervention period, the IG showed significant increases in energy intake (+1206.9 kcal, p = 0.007), protein (+21.25 g, p = 0.003), PUFA (+9.67 g, p = 0.002), fibre (+2.63 g, p = 0.037), vitamin A (+828.57 µg, p = 0.002), vitamin B1 (+5.00 mg, p = 0.001), vitamin B2 (+4.20 mg, p = 0.001), vitamin C (+95.91 mg, p < 0.001), and vitamin E (+7.21 mg, p < 0.001). Calcium (+398.09 mg, p < 0.001) and iron (+23.86 mg, p < 0.001) also improved. In contrast, the CG showed minimal changes or declines in these parameters, including energy (-57.2 kcal), protein (-10.3 g), PUFA (-1.80 g), fibre (-6.86 g), and vitamins A, B1, B2, C, and E. INSERT TABLE 1 ABOUT HERE Following this intervention, significant improvements were observed in several key biomarkers for the IG compared to the CG (Table 2). INSERT TABLE 2 ABOUT HERE Haematological parameters are reported in Table 2, with individual changes in haemoglobin shown in Figure 2. Several parameters, including serum haemoglobin, PCV, MCHC, MCH, and MCV, significantly improved in the IG compared to the CG. Specifically, the IG showed increases in haemoglobin (+3.08 g/dL, p = 0.040), PCV (+2.23%, p = 0.017), MCHC (+1.12, p = 0.080), MCH (+1.12, p = 0.080), and MCV (+2.26, p = 0.080). In contrast, the CG showed either minimal changes or non-significant declines in these parameters. Further, the IG also exhibited a significant increase in serum ferritin (Figure 3a). In the IG, 9 out of 12 participants showed an improvement in serum ferritin levels, with an average change of +6.78 ± 0.9 ng/mL (Pre: 44.76 ± 29.3, Post: 51.54 ± 28.4; p < 0.001). Conversely, in the CG (Figure 3b), 10 out of 12 participants exhibited a decline in serum ferritin levels, with an average change of -4.41 ± 0.0 ng/mL (Pre: 30.31 ± 20.4, Post: 25.90 ± 14.8; p = 0.371). The between-group comparison showed a statistically significant difference (p for IG vs. CG = <0.001). INSERT FIGURE 3 ABOUT HERE Mean vitamin D levels were IG Pre: 30.55±10.2 ng/mL. Post: 42.02±9.6 ng/mL, Change: +11.47±0.6 ng/ml (p < 0.001); CG Pre: 34.55±10.8 ng/mL, Post: 33.96±10.7 ng/mL, Change: -0.59±0.1 ng/ml (p = 0.840); p for IG vs. CG = <0.001). At baseline, seven of 13 IG athletes were deficient in a total of 25-OH vitamin D (below 30 ng/ml), and six out of 13 were sufficient (30-100 ng/mL). At the end of the intervention, only one athlete remained deficient, while 12 out of 13 showed sufficiency. At baseline, six out of 14 CG athletes were deficient in total 25-OH vitamin D, and eight out of 14 were sufficient. By the end of the intervention, seven athletes showed insufficiency. Discussion To the extent of our knowledge, this is the first RCT designed to evaluate the effectiveness of culturally tailored, evidence-based, personalized sports dietary advice in improving the nutritional status and dietary intake of national-level track and field athletes in South Asia. The main findings indicate that personalized dietary advice, combined with appropriate micronutrient supplementation, significantly enhances nutritional status, as evidenced by improvements in dietary intake, including energy and micronutrient intake, as well as biochemical parameters such as serum haemoglobin levels, other red blood cell parameters, serum ferritin levels, and total 25-hydroxy vitamin D levels. The significant improvements in dietary nutrient intake observed in the IG athletes compared to the CG following the intervention highlight the effectiveness of the dietary modifications implemented. Notably, the enhanced energy intake in the IG is particularly promising for improving athletic performance. This finding is critical, as a considerable proportion of athletes suffer from low energy availability (LEA), which can lead to relative energy deficiency in sport (RED-S). A meta-analysis of 59 studies revealed that 44.7% of 6,118 athletes had LEA, including 44.2% of female and 49.4% of male athletes [ 18 ]. Furthermore, 63.0% of 730 athletes across eight studies were identified as being at risk of RED-S [ 18 ]. Another study reported that 80% of elite Australian female athletes exhibited symptoms of RED-S [ 19 ]. The prevalence of LEA and RED-S could be even higher in developing countries like Sri Lanka, where energy intake is disproportionately low compared to energy expenditure due to factors such as the ongoing economic crisis [ 20 ]. To address these challenges, our intervention introduced calorie-dense foods and sports supplements to mitigate the risk of LEA among athletes. A similar trial assessing the effects of an eight-week nutrition education program and controlled dietary modification) found significant reductions in energy deficits, with a 97% increase in daily calorie intake among the IG. Protein intake also increased significantly, meeting 88% of the recommended levels, while carbohydrate intake increased insignificantly to meet 89% of the standards post-intervention [ 11 ]. These results align with our findings, as IG athletes in this study demonstrated significant increases in protein intake, while carbohydrate intake changes were insignificant. Dietary protein intake in Sri Lanka is notably low, with only 10% of the population's calorie intake derived from proteins [ 21 ]. Our athletes’ dietary diaries revealed similar patterns, with some meals containing negligible amounts of protein. To address this, we implemented dietary modifications to meet recommended protein intake levels of 1.4–2.0 g/kg/day as suggested by the latest guidelines [ 6 ]. These adjustments included distributing protein intake throughout the day. In contrast, carbohydrate intake in the Sri Lankan population typically exceeds nutritional guidelines, contributing approximately 72% of total energy intake [ 21 ]. Consequently, we did not observe a significant increase in carbohydrate intake, likely because the athletes were already consuming an adequate amount. Regarding fat intake, the IG athletes demonstrated significant increases in PUFAs, as coconut oil was replaced with extra virgin olive oil (EVOO) or other healthier options. Coconut oil, while common in Sri Lankan diets, contains higher levels of saturated fats [ 22 ]. However, we could not assess changes in saturated fatty acid intake due to the limitations of the Nutri-Survey Software, which lacked this specific component in its analysis. Dietary fibre intake significantly increased among IG athletes, a result of encouraging the inclusion of fruits, nuts, vegetables, and green leafy vegetables in their meals and snacks. Finally, micronutrient intake among IG athletes showed significant improvements compared to the CG and their pre-intervention levels. This was achieved through dietary modifications and the empirical supplementation of multivitamins and multimineral during the 16-week intervention. The increased availability of vitamins and minerals through these strategies addressed the inadequacies typical of Sri Lankan diets [ 23 ], further enhancing the nutritional status of the IG athletes. Iron and vitamin D deficiencies, common among athletes, also merit attention. Iron, a critical component of oxygen transport and energy production, is essential for optimal athletic performance [ 24 ]. However, a cross-sectional study of 1,190 athletes reported a 19.7% prevalence of iron deficiency, with younger athletes, females, and those with lower VO 2 peak values being most affected [ 25 ]. This study further reported that athletes with iron deficiency were younger (18.1 ± 8.4 vs. 22.8 ± 12.1 years, P < 0.001), more frequently female (64.5% vs. 26.8%, P 50 ml/min/kg (8.5% vs. 16.1%, P = 0.003). Iron deficiency in athletes can negatively impact various aspects beyond aerobic capacity, including strength, immune function, fatigue, and mood [ 26 ]. These deficiencies may impair endurance, as well as power, speed, coordination, concentration, recovery, and ultimately, overall performance [ 27 ]. Several studies indicate that a significant number of athletes suffer from vitamin D insufficiency or deficiency [ 28 ]. Hamilton and colleagues found that 84% of 3,422 professional soccer players in Qatar had serum vitamin D levels below 30 ng/mL, with 12% showing severe deficiency (< 10 ng/mL) [ 29 ]. Another study revealed that hypovitaminosis D is prevalent among National Basketball Association players, with 32.3% and 41.2% of professional basketball players experiencing vitamin D deficiency (< 20 ng/mL) and insufficiency (20–30 ng/mL), respectively [ 30 ]. Additionally, a large cohort study of college athletes reported that over one-third of players had abnormal vitamin D levels [ 31 ]. Although we incorporated a random sample of elite and highly trained track and field full-time athletes of both genders, representing the national athletic pool, these athletes exhibited moderate to severe micronutrient deficiencies, as identified through appropriate biochemical testing. Hence, supplementing these commonly deficient micronutrients has been shown to address deficiencies and improve athletic performance [ 32 ]. The current results align with those of previous studies. For instance, a systematic review with meta-analysis (17 studies, 443 participants) indicated beneficial effects of iron supplementation on haemoglobin and ferritin levels among iron-deficient non-anaemic (IDNA) endurance athletes [ 33 ]. Similarly, DellaValle et al. observed improvements in ferritin levels, energetic efficiency, and lactate response during endurance exercise in an RCT involving IDNA rowers (n = 40 women), suggesting that iron supplementation could enhance the benefits of endurance training [ 34 ]. With regards to vitamin D supplementation, our findings align with previous trials where a double-blind, placebo-controlled study on 2000 IU of vitamin D for three weeks showed positive effects on serum 25(OH)D levels in endurance-trained runners, along with a significant decrease in post-exercise biomarkers [ 35 ]. The supplemented group demonstrated a significant increase in baseline 25(OH)D levels (34.9 ± 4.7 vs. 40.3 ± 4.9 ng/mL, p = 0.02) and a higher post-intervention 25(OH)D level compared to placebo (40.3 ± 4.9 vs. 31.8 ± 4.2 ng/mL, p < 0.05). This study demonstrated that a personalized approach is more effective than a one-size-fits-all approach in restoring adequate vitamin D levels in athletes [ 36 ]. Strengths and limitations The main strength of this study is its personalized approach to both diet and supplementation. This distinguishes it from previous studies that typically focused on a one-size-fits-all intervention, such as administering the same protein dose or one vitamin supplement to all participants. In contrast, we carefully tailored dietary advice and supplement doses for each individual based on available evidence, taking into account the specific needs of each athlete. For example, protein supplements were provided only when individuals had difficulty meeting their protein requirements through food, and vitamin D supplementation was adjusted according to the severity of the deficiency, with higher doses for those with severe deficiencies and lower doses for those with insufficiency. This personalized approach ensured that the intervention was both effective and practical, leading to significant improvements in key biomarkers, including Hb, RBC parameters, serum ferritin, and vitamin D levels, as demonstrated by post-intervention biochemical tests. Despite these strengths, the study has several limitations including the small sample size which may affect the generalizability of findings. Furthermore, due to the nature of the trial, we could not directly measure participant compliance with the intervention, which could have influenced the outcomes. Another limitation was the inability to measure the full range of serum micronutrient levels, including calcium, vitamin A, and vitamin E, as these tests were expensive. Additionally, while serum ferritin is a common marker for iron status, its interpretation can be complicated by the inflammatory status of athletes, which may fluctuate due to intense physical training [ 37 ]. This could have impacted the accuracy of the serum ferritin results, as ferritin levels may appear normal despite depleted iron stores during periods of systemic inflammation [ 38 ]. Future studies could consider including larger sample sizes, employing more precise measures of compliance, and expanding the range of micronutrient assessments to obtain a more complete picture of nutritional status. It would also be valuable to replicate this intervention in diverse athlete populations after proper screening for nutritional and training status to validate these findings in broader contexts. To further enhance the impact of personalized nutrition interventions, future research could also explore the long-term effects of sustained personalized sports nutrition interventions on athletic performance and health. Conclusions In conclusion, this study demonstrates the effectiveness of a culturally appropriate, evidence-based, personalized dietary advice in addressing micronutrient deficiencies and improving the nutritional status, and dietary intake among track and field athletes. The intervention, based on individual dietary intakes and biochemical parameters, led to significant improvements in key biomarkers such as Hb, serum ferritin, and vitamin D levels. This trial provides valuable insights into the benefits of personalized nutrition in enhancing athlete health and performance. Abbreviations BMI: Body Mass Index; CG: Control Group; Change: Change from Pre to Post; CLIA: Chemiluminescence Immunoassay; Dietary Fibre: Dietary Fibre; FBC: Full Blood Count; FM: Fat Mass; FFM: Fat-Free Mass; g/kg/day: Grams per Kilogram per Day; Haemoglobin (Hb): Haemoglobin; IG: Intervention Group; IU: International Units; kcal: Kilocalories; LBM: Lean Body Mass; MCH: Mean Corpuscular Haemoglobin; MCHC: Mean Corpuscular Haemoglobin Concentration; MCV: Mean Corpuscular Volume; PCV: Packed Cell Volume; Polyunsaturated Fatty Acids (PUFA): Polyunsaturated Fatty Acids; Pre: Pre-intervention; Post: Post-intervention; RCT: Randomized Controlled Trial. Declarations Acknowledgements We express our gratitude to all the athletes who participated in this trial, as well as to all other contributors who helped improve the study. Funding No funding was received for conducting this study, however, a part of the fees for biochemical tests were covered by Nawaloka Hospitals PLC, Sri Lanka. Conflicts of interest The authors declare no competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Consent for publication Not applicable. Availability of data and materials The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. Ethical approval and consent to participate The qualitative study used in the multi-modal approach during the development of the questionnaire was conducted in accordance with the standards set by the Declaration of Helsinki. Ethical approval was obtained from the Ethics Review Committee of the Faculty of Medicine, University of Peradeniya, Sri Lanka, prior to conducting the study (Ref No. 2022/EC/66). All participants provided written informed consent to participate in the study. Authors' contribution RJ conceived and designed the study. RJ and KW were involved in data collection and analysis. RJ and KW contributed to drafting the manuscript. NSK, TM, IN and APH, as supervisory team members, participated in the revision of the paper. All authors carefully reviewed and approved the final version of the manuscript. The full trial protocol access ResearchGate:https://www.researchgate.net/publication/382314659_The_effects_of_a_nutritional_intervention_on_the_sports_nutrition_knowledge_and_nutritional_ status_of_elite_athletes_protocol_for_a_randomized_controlled_trial. Bibliography: Jayawardena R, Weerasinghe K, Nanayakkara I, Madhujith T, Hills AP, Kalupahana NS. 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The effects of a nutritional intervention on the sports nutrition knowledge and nutritional status of elite athletes: protocol for a randomized controlled trial. 2024. Gallant TL, Ong LF, Wong L, Sparks M, Wilson E, Puglisi JL, et al. Low Energy Availability and Relative Energy Deficiency in Sport: A Systematic Review and Meta-analysis. Sports Med. 2024. Rogers MA, Appaneal RN, Hughes D, Vlahovich N, Waddington G, Burke LM, et al. Prevalence of impaired physiological function consistent with Relative Energy Deficiency in Sport (RED-S): an Australian elite and pre-elite cohort. Br J Sports Med. 2021;55(1):38-45. BASAK S, DATTA S, ROY SD, MAJUMDAR A, SAHA S. ECONOMIC CRISIS OF SRILANKA. Jayawardena R, Thennakoon S, Byrne N, Soares M, Katulanda P, Hills A. Energy and nutrient intakes among Sri Lankan adults. Int Arch Med. 2014;7:34. Swarnamali H, Ranasinghe P, Jayawardena R. Changes in serum lipids following consumption of coconut oil and palm olein oil: A sequential feeding crossover clinical trial. Diabetes & Metabolic Syndrome: Clinical Research & Reviews. 2024;18(6):103070. Jayawardena R, Jeyakumar DT, Gamage M, Sooriyaarachchi P, Hills AP. Fruit and vegetable consumption among South Asians: A systematic review and meta-analysis. Diabetes Metab Syndr. 2020;14(6):1791-800. Alaunyte I, Stojceska V, Plunkett A. Iron and the female athlete: a review of dietary treatment methods for improving iron status and exercise performance. J Int Soc Sports Nutr. 2015;12:38. Keller K, Friedrich O, Treiber J, Quermann A, Friedmann-Bette B. Iron deficiency in athletes: Prevalence and impact on VO(2) peak. Nutrition. 2024;126:112516. Sim M, Garvican-Lewis LA, Cox GR, Govus A, McKay AKA, Stellingwerff T, et al. Iron considerations for the athlete: a narrative review. Eur J Appl Physiol. 2019;119(7):1463-78. Rubeor A, Goojha C, Manning J, White J. Does Iron Supplementation Improve Performance in Iron-Deficient Nonanemic Athletes? Sports Health. 2018;10(5):400-5. Bezuglov E, Tikhonova A, Zueva A, Khaitin V, Waśkiewicz Z, Gerasimuk D, et al. Prevalence and Treatment of Vitamin D Deficiency in Young Male Russian Soccer Players in Winter. Nutrients. 2019;11(10). Hamilton B, Whiteley R, Farooq A, Chalabi H. Vitamin D concentration in 342 professional football players and association with lower limb isokinetic function. J Sci Med Sport. 2014;17(1):139-43. Grieshober JA, Mehran N, Photopolous C, Fishman M, Lombardo SJ, Kharrazi FD. Vitamin D Insufficiency Among Professional Basketball Players: A Relationship to Fracture Risk and Athletic Performance. Orthop J Sports Med. 2018;6(5):2325967118774329. Villacis D, Yi A, Jahn R, Kephart CJ, Charlton T, Gamradt SC, et al. Prevalence of Abnormal Vitamin D Levels Among Division I NCAA Athletes. Sports Health. 2014;6(4):340-7. Jayawardena R, Weerasinghe K, Madhujith T, Hills AP, Kalupahana N. Perceptions of the importance of sports nutrition knowledge and barriers in implementing them: a qualitative study among track and field stakeholders in Sri Lanka. BMC Nutr. 2024;10(1):17. Burden RJ, Morton K, Richards T, Whyte GP, Pedlar CR. Is iron treatment beneficial in, iron-deficient but non-anaemic (IDNA) endurance athletes? A systematic review and meta-analysis. Br J Sports Med. 2015;49(21):1389-97. DellaValle DM, Haas JD. Iron supplementation improves energetic efficiency in iron-depleted female rowers. Med Sci Sports Exerc. 2014;46(6):1204-15. Żebrowska A, Sadowska-Krępa E, Stanula A, Waśkiewicz Z, Łakomy O, Bezuglov E, et al. The effect of vitamin D supplementation on serum total 25(OH) levels and biochemical markers of skeletal muscles in runners. J Int Soc Sports Nutr. 2020;17(1):18. Tuma C, Schick A, Pommerening N, Braun H, Thevis M. Effects of an Individualized vs. Standardized Vitamin D Supplementation on the 25(OH)D Level in Athletes. Nutrients. 2023;15(22). Cerqueira É, Marinho DA, Neiva HP, Lourenço O. Inflammatory Effects of High and Moderate Intensity Exercise-A Systematic Review. Front Physiol. 2019;10:1550. Dignass A, Farrag K, Stein J. Limitations of Serum Ferritin in Diagnosing Iron Deficiency in Inflammatory Conditions. Int J Chronic Dis. 2018;2018:9394060. Tables Tables 1 to 2 are available in the Supplementary Files section Additional Declarations No competing interests reported. Supplementary Files Table1.docx Table2.docx SupplementaryMaterial1.docx Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 22 Jan, 2025 Editor assigned by journal 09 Jan, 2025 Submission checks completed at journal 09 Jan, 2025 First submitted to journal 08 Jan, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5789887","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":399956249,"identity":"bd97e939-ecc6-4916-9b28-2070452f45fe","order_by":0,"name":"Ranil Jayawardena","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA/ElEQVRIiWNgGAWjYJCCAw8qGBIYGBgbGB4AeQZgsYIE/FoSzkC1JMC1GODXwpDYxgBRQZQW8/azBw8kzruTZ3D+cOODBAa7aHMG5ocfGAzScGqROZOXcCBx27NigxuJzUCjk3N3NrAZSzAY5ODUIsGQYwDUcjhxww3GNokEhgO5Gw4wmAEdVoFbC/8boJY5QC3nD8K0sH/Dr0UCZEsDUMuBRJgWHpAteBwmAbQl4dizxJlgvxgA/dLMUyyRgMf7Evw5xh8+1NxJ7Dt//OGDDxV2udvZ2zd++FCRjFMLFBxgUDgAokGRwszAAI0mAlrkGwirGgWjYBSMghEKAFjDXomNn+80AAAAAElFTkSuQmCC","orcid":"","institution":"University of Colombo","correspondingAuthor":true,"prefix":"","firstName":"Ranil","middleName":"","lastName":"Jayawardena","suffix":""},{"id":399956250,"identity":"44292fb0-f000-4f1a-b1e8-24fc0c3a8bd1","order_by":1,"name":"Kalani Weerasinghe","email":"","orcid":"","institution":"University of Colombo","correspondingAuthor":false,"prefix":"","firstName":"Kalani","middleName":"","lastName":"Weerasinghe","suffix":""},{"id":399956251,"identity":"c1464eb6-8bf4-4d4d-a3bb-ad01d5794e42","order_by":2,"name":"Indu Nanayakkara","email":"","orcid":"","institution":"University of Peradeniya","correspondingAuthor":false,"prefix":"","firstName":"Indu","middleName":"","lastName":"Nanayakkara","suffix":""},{"id":399956252,"identity":"af1243f7-fa69-44ac-b535-b0561355ade0","order_by":3,"name":"Terrence Madhujith","email":"","orcid":"","institution":"University of Peradeniya","correspondingAuthor":false,"prefix":"","firstName":"Terrence","middleName":"","lastName":"Madhujith","suffix":""},{"id":399956253,"identity":"76f6c55c-4de0-47c4-a050-34836e5b94aa","order_by":4,"name":"Andrew P Hills","email":"","orcid":"","institution":"University of Tasmania","correspondingAuthor":false,"prefix":"","firstName":"Andrew","middleName":"P","lastName":"Hills","suffix":""},{"id":399956254,"identity":"dc4d87cb-50ca-457d-83d5-43b5f90334b3","order_by":5,"name":"Nishan Sudheera Kalupahana","email":"","orcid":"","institution":"United Arab Emirates University","correspondingAuthor":false,"prefix":"","firstName":"Nishan","middleName":"Sudheera","lastName":"Kalupahana","suffix":""}],"badges":[],"createdAt":"2025-01-08 14:23:27","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5789887/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5789887/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":73655184,"identity":"02e0bc7d-373b-4519-97d2-f6ac0df6082f","added_by":"auto","created_at":"2025-01-13 10:09:32","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":47810,"visible":true,"origin":"","legend":"\u003cp\u003eCONSORT diagram\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-5789887/v1/43f1d7d3be570fea8ac3742b.png"},{"id":73655206,"identity":"00c23172-d320-42aa-ae55-b7290b6ea94c","added_by":"auto","created_at":"2025-01-13 10:09:34","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":77498,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ea.\u003c/strong\u003e Change in serum Haemoglobin (g/dL) from pre- to post-intervention in the intervention group\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eb.\u003c/strong\u003e Change in serum Haemoglobin (g/dL) from pre- to post-intervention in the control group\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-5789887/v1/896c165906bc0b92d1cdf954.png"},{"id":73655738,"identity":"4b4c855b-29d3-4bc0-a646-99539fa2a421","added_by":"auto","created_at":"2025-01-13 10:17:36","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":173626,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ea.\u003c/strong\u003e Change in serum Ferritin levels (ng/mL) from pre- to post-intervention in the intervention group. \u003cstrong\u003eb.\u003c/strong\u003e Change in serum Ferritin levels (ng/mL) from pre- to post-intervention in the control group\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-5789887/v1/89ff740be9e7502e83a5a9f2.png"},{"id":73655209,"identity":"7bf48853-09bc-46a6-b7e1-a950554c11ca","added_by":"auto","created_at":"2025-01-13 10:09:34","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":212500,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ea.\u003c/strong\u003e Comparison of changes in Total 25-OH Vitamin D categories in the intervention group (ng/mL)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eb.\u003c/strong\u003e Comparison of changes in Total 25-OH Vitamin D categories in the control group (ng/mL)\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eSufficiency: 30-100 ng/mL, Deficiency: Below 30 ng/mL\u003c/em\u003e\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-5789887/v1/73f8630077951a0dd6f0a5a1.png"},{"id":73656982,"identity":"800534aa-0660-4030-ba66-657b298ec6a0","added_by":"auto","created_at":"2025-01-13 10:33:44","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":964509,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5789887/v1/3641c7d9-856c-4454-8fa6-826b13409a31.pdf"},{"id":73655189,"identity":"f1286f0c-d46f-4e28-82ce-f795365c0677","added_by":"auto","created_at":"2025-01-13 10:09:33","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":24948,"visible":true,"origin":"","legend":"","description":"","filename":"Table1.docx","url":"https://assets-eu.researchsquare.com/files/rs-5789887/v1/d5929c2c17cbffb2da924e68.docx"},{"id":73655200,"identity":"643f98c7-2d81-4afe-84a7-9f60432f89b5","added_by":"auto","created_at":"2025-01-13 10:09:34","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":19436,"visible":true,"origin":"","legend":"","description":"","filename":"Table2.docx","url":"https://assets-eu.researchsquare.com/files/rs-5789887/v1/a4694175259d70aac2d1da52.docx"},{"id":73655718,"identity":"cca0e774-d445-4ad7-8f2f-41fcc111eb2c","added_by":"auto","created_at":"2025-01-13 10:17:33","extension":"docx","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":22241,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryMaterial1.docx","url":"https://assets-eu.researchsquare.com/files/rs-5789887/v1/5253df8129545abab3ab4af7.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Culturally appropriate, evidence-based, personalized dietary advice to improve the nutritional status of track and field athletes: a randomized controlled trial","fulltext":[{"header":"Introduction","content":"\u003cp\u003eOptimal nutrition is crucial for the provision of energy and nutrients for sports activities, facilitating post-exercise recovery, enhancing sports performance, and promoting overall well-being [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Elite athletes often require more energy, protein, and certain micronutrients than their non-athletic counterparts due to the heightened physical demands of intense training. The daily requirements for energy, carbohydrates, and protein are significantly higher in athletes than in non-athletes, given the increased physical exertion associated with their training and/or larger body size [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. For example, throwers, who typically have a larger body mass and engage in rigorous training sessions lasting 1.5 to 4 hours, may have additional caloric needs [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. These sessions deplete glycogen stores significantly, and if these stores are not replenished during or after exercise, subsequent performance can be compromised, ultimately reducing overall athletic performance [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Additionally, adult endurance athletes often undergo training programs involving 500 to 1,000 hours per year or running distances exceeding 150 km per week, leading to significant energy expenditure [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWhile the general population requires approximately 0.8 grams of protein per kilogram of body mass per day (g/kg/day), athletes need between 1.2 to 2.0 g/kg/day, depending on whether they are engaged in aerobic or resistance exercise, with the higher end of the range being more suitable for resistance training [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Additionally, protein needs increase in specific circumstances, such as during periods of intensified training or injury recovery [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. For optimal metabolic adaptation, and to support muscle protein synthesis\u0026mdash;a key marker of repair, growth, and adaptation\u0026mdash;athletes should consume 0.25 to 0.40 g/kg of protein per meal [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. This helps in preserving lean body mass, which is crucial for athletic performance [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Dietary fat is also an essential component of an athlete's training diet, with general nutrition guidelines emphasizing the importance of the type of fat consumed. Athletes are encouraged to consume more omega-3 polyunsaturated fatty acids while reducing intake of saturated and trans fats [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. For endurance athletes, excessive fat restriction is not recommended, as it can lead to insufficient energy intake, resulting in fatigue, poor performance, and an increased risk of illness or injury [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. A fat intake of approximately 35% of total calories is suggested to ensure adequate caloric intake, support intramuscular triglyceride super-compensation, and allow for sufficient carbohydrate intake to replenish glycogen stores [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn this context, the carbohydrate and protein intake of some athletes may be inadequate to meet the demands of athletic performance, and calcium intake may fall below the levels recommended for maintaining bone health [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. A recent review found that master athletes participating in world athletics championship competitions generally do not consume sufficient protein, carbohydrates, and various micronutrients to support optimal performance, as determined by 24-hour dietary recalls [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. In a similar study involving sprint athletes over three years, consistently low intakes of iron were observed in girls, and both sexes showed low intake of calcium, vitamin E, and B\u003csub\u003e2\u003c/sub\u003e, while sodium intake exceeded the upper reference limit [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eSeveral sports nutrition interventions, including education, counselling, and dietary modifications, have shown positive effects on athletes' nutritional status. A randomized controlled trial demonstrated that an eight-week nutrition education program combined with controlled dietary modifications significantly reduced energy deficits, improving daily calorie intake (97% of needs) and protein intake (88% of recommendations). Athletes in the intervention group also exhibited increased intake of key vitamins (A, B\u003csub\u003e9\u003c/sub\u003e, B\u003csub\u003e12\u003c/sub\u003e, C, and E) and minerals (calcium, iron, zinc, and selenium), highlighting the benefits of structured nutritional strategies [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. In addition to nutritional consultation interventions, another study was conducted on football players to examine the impact of vitamin D supplementation on training adaptations [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The findings indicated significant improvements in power-related metrics, such as vertical jumps (squat jump, countermovement jump), following interval training with a daily dose of 5,000 IU of vitamin D for 8 weeks. In a parallel, randomized, double-blind study on iron supplementation, iron-deficient but non-anaemic athletes were given 30 mg of elemental iron as ferrous sulphate daily for six weeks [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. This regimen significantly raised serum ferritin levels compared to the placebo group (P\u0026thinsp;=\u0026thinsp;0.01). Similarly, another trial reported that 7 to 8 months of multivitamin/mineral supplementation enhanced the blood nutritional status of certain vitamins in athletes from various sports, including basketball, gymnastics, rowing, and swimming [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAlthough there is no nationally published data on the dietary habits of athletes in Sri Lanka, a study on the nutritional intake of undergraduate athletes revealed that they regularly do not consume sufficient energy, proteins, and micronutrients [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Therefore, this randomized controlled trial aimed to assess the effectiveness of a culturally tailored, evidence-based, personalized sports dietary advice in improving the nutritional status of elite-level track and field athletes in Sri Lanka.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eThe CONSORT 2010 statement guidelines regarding randomized trials (www.consort-statement.org) were followed for this RCT [16] and the corresponding checklist is provided in Supplementary Material 1.\u003c/p\u003e\n\u003cdiv id=\"Sec3\"\u003e\n \u003cp\u003eTrial design\u003c/p\u003e\n \u003cp\u003eThis parallel-group randomized controlled trial evaluated the impact of a culturally tailored, evidence-based, personalized sports dietary advice on the nutritional status of track and field athletes in Sri Lanka over 16 weeks. Conducted at the Department of Physiology, Faculty of Medicine, University of Colombo, the study adhered to ethical guidelines outlined in the Helsinki Declaration. Participants provided written informed consent with the option to withdraw or continue follow-up without affecting their clinical care. Ethical approval was obtained from the Institutional Ethical Review Committee, Faculty of Medicine, University of Peradeniya, Sri Lanka (2023/EC/71). The trial is registered with the Sri Lanka Clinical Trials Registry (SLCTR/2024/013) and has a Universal Trial Number (UTN): U1111-1304-8890. The CONSORT diagram (Fig. 1) illustrates the flow of this RCT.\u003c/p\u003e\n\u003c/div\u003e\n\u003cp\u003eParticipants\u003c/p\u003e\n\u003cp\u003eEligible participants included elite track and field athletes of both genders. Potential participants were recruited through contacts from coaches, fellow athletes, and open advertisements in social media groups, targeting national-level athletes. Participants were screened two weeks prior to the intervention and were required to provide verbal and written informed consent.\u003c/p\u003e\n\u003cp\u003eIntervention\u003c/p\u003e\n\u003cp\u003eThe intervention comprised a culturally tailored, personalized dietary prescription provided by the principal investigator (RJ), designed to meet the individual energy, macronutrient, and micronutrient needs of each athlete. This prescription was based on a comprehensive assessment of dietary intake, body composition, physical training load, and biochemical parameters. To ensure effective guidance, the intervention included three structured sessions delivered at week 0, week 4, and week 8, each lasting approximately 15\u0026ndash;20 minutes. Ongoing support and advice were provided via WhatsApp throughout the intervention period, ensuring the adherence.\u003c/p\u003e\n\u003cp\u003eI. Personalization and cultural appropriateness\u003c/p\u003e\n\u003cp\u003eAthletes were guided to achieve an appropriate energy balance tailored to their individual training loads and body composition. Energy requirements were estimated using practical methods, taking into account contextual constraints. Additional energy supplements were prescribed for those with significant energy deficits, while athletes with high adiposity or excessive energy intake received culturally sensitive dietary advice to manage calorie intake effectively.\u003c/p\u003e\n\u003cp\u003eII. Macronutrient guidelines\u003c/p\u003e\n\u003cp\u003eAthletes were advised to adhere to current carbohydrate intake guidelines, with culturally specific recommendations provided for carbohydrate-rich foods. Protein needs were calculated as 1.2\u0026ndash;1.6 g/kg body weight daily, distributed across four protein-rich meals, with 0.3\u0026ndash;0.4 g/kg body weight per meal. Recommendations included culturally common protein sources, and whey protein supplements were introduced when dietary intake was insufficient. Advice focused on reducing saturated fats from foods like coconut oil and encouraging the use of healthier unsaturated fats, such as extra virgin olive oil and gingelly oil. Omega-3 fish oil supplementation was recommended for participants with inadequate fish consumption.\u003c/p\u003e\n\u003cdiv id=\"Sec8\"\u003e\n \u003cp\u003eIII. Micronutrient optimization\u003c/p\u003e\n \u003cp\u003eFor athletes with clinically confirmed deficiencies, tailored supplementation protocols were implemented. For instance, Vitamin D insufficiency was treated with doses ranging from 1,000 IU daily to 60,000 IU weekly based on blood levels. Iron supplementation was guided by serum ferritin and haemoglobin levels, with additional multivitamin, calcium, and mineral supplements prescribed as necessary.\u003c/p\u003e\n \u003cp\u003eA balanced intake of grains, fruits, vegetables, nuts, and legumes was encouraged. However, high-fibre foods were restricted during pre-training and competitive periods to avoid gastrointestinal discomfort.\u003c/p\u003e\n\u003c/div\u003e\n\u003cp\u003eIntervention group\u003c/p\u003e\n\u003cp\u003eThe intervention group (n\u0026thinsp;=\u0026thinsp;15) engaged in one-on-one consultations with the principal investigator, receiving comprehensive nutrition advice which includes dietary practices and prescription of micronutrients and sports supplements.\u003c/p\u003e\n\u003cp\u003eControl group\u003c/p\u003e\n\u003cp\u003eThe control group (n\u0026thinsp;=\u0026thinsp;15) did not receive any intervention but was followed throughout the study. After the intervention period, participants in the control group were provided with basic nutritional advice.\u003c/p\u003e\n\u003cdiv id=\"Sec11\"\u003e\n \u003cp\u003eOutcomes\u003c/p\u003e\n \u003cdiv id=\"Sec12\"\u003e\n \u003cp\u003eDietary assessment\u003c/p\u003e\n \u003cp\u003eThe nutritional status of the athletes was assessed both before the intervention (in the two weeks lead in before the intervention) and after the intervention (at the end of the 16th week) using seven-day food diaries, with food portions and type of food consumed analysed to assess diet quality. The total intake over seven days was averaged and reported as pre- and post-intervention values. Participants were given written and verbal instructions on how to complete the seven-day food records in a provided booklet. The energy content of each food component was calculated using standard energy values for portion sizes. Daily energy intake macro- and micronutrient intake was performed using Nutri-Survey Software modified with Sri Lankan food composition data.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec13\"\u003e\n \u003cp\u003eBiochemical measurements\u003c/p\u003e\n \u003cp\u003eA full blood count (FBC) was analyzed using the SYSMEX XE-2100 Haematology Automated Analyzer (Block Scientific Inc., United States) to assess packed cell volume (PCV), Haemoglobin, mean corpuscular haemoglobin concentration (MCHC), mean corpuscular haemoglobin (MCH), and mean corpuscular volume (MCV). Additionally, serum vitamin D3 levels were assessed using the MAGLUMI 2000 analyzer through a Competitive Chemiluminescence Immunoassay (CLIA) (Snibe; Shenzhen, P.R. China), which quantitatively measures the sum of both 25-(OH) vitamin D3 (cholecalciferol) and 25-(OH) vitamin D2 (ergocalciferol) in the specimen. Serum Total 25-OH Vitamin D categories were defined as Sufficiency: 30\u0026ndash;100 ng/mL, and Deficiency: below 30 ng/mL. Serum ferritin levels were measured using the Cobas e601 device with ECLIA technology (Roche Diagnostics International AG, Rotkreuz, Switzerland). All biochemical assessments were conducted at an accredited laboratory (Nawaloka Metropolis Laboratory, Nawaloka Hospital PLC), following standard procedures. Details regarding the sample size calculation, randomization procedures, and blinding protocols have been published elsewhere [17].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec14\"\u003e\n \u003cp\u003eStatistical methods\u003c/p\u003e\n \u003cp\u003eDescriptive statistics were employed to summarize participant characteristics. Independent sample t-tests were used to compare baseline and post-intervention characteristics between groups, while paired t-tests assessed within-group changes for normally distributed continuous variables. The Chi-square test was applied to evaluate improvements in categorical variables, such as Vitamin D levels, before and after the intervention within each group (IG and CG). In all the statistical tests, a p-value of \u0026lt;\u0026thinsp;0.05 was considered significant.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eAmong the 30 participants initially enrolled in the study, 13 from the IG and 14 from the CG completed this intervention\u0026nbsp;(Figure 1).\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 624px;\"\u003e\n \u003cp\u003eINSERT FIGURE 1 ABOUT HERE\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eThe results presented here are based on the 27 participants who completed the study, following the per-protocol analysis approach. The IG had an average age of 23.4 \u0026plusmn; 2.8 years, comprising 8 males and 5 females. In comparison, the CG had a mean age of 21.9 \u0026plusmn; 3.9 years, with 9 males and 5 females. The average duration of sports experience was 7.15 \u0026plusmn; 3.60 years for the IG and 5.92 \u0026plusmn; 3.73 years for the CG (p = 0.394). Regarding performance levels, 38% of IG participants and 36% of CG participants were categorized as elite athletes, while 62% of the IG and 64% of the CG were classified as highly trained athletes. The participants competed in four track and field disciplines: each group had one sprinter, the IG had seven middle-distance runners and three long-distance runners, while the CG had 10 and two, respectively, and the IG had two jumpers, whereas the CG had one.\u003c/p\u003e\n\u003cp\u003eFollowing this 16-week evidence-based sports nutrition intervention, significant improvements were observed in energy intake and macro and micronutrient parameters for the IG compared to the CG (Table 1).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDuring the intervention period, the IG showed significant increases in energy intake (+1206.9 kcal, p = 0.007), protein (+21.25 g, p = 0.003), PUFA (+9.67 g, p = 0.002), fibre (+2.63 g, p = 0.037), vitamin A (+828.57 \u0026micro;g, p = 0.002), vitamin B1 (+5.00 mg, p = 0.001), vitamin B2 (+4.20 mg, p = 0.001), vitamin C (+95.91 mg, p \u0026lt; 0.001), and vitamin E (+7.21 mg, p \u0026lt; 0.001). Calcium (+398.09 mg, p \u0026lt; 0.001) and iron (+23.86 mg, p \u0026lt; 0.001) also improved. In contrast, the CG showed minimal changes or declines in these parameters, including energy (-57.2 kcal), protein (-10.3 g), PUFA (-1.80 g), fibre (-6.86 g), and vitamins A, B1, B2, C, and E.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 624px;\"\u003e\n \u003cp\u003eINSERT TABLE 1 ABOUT HERE\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eFollowing this intervention, significant improvements were observed in several key biomarkers for the IG compared to the CG (Table 2).\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 624px;\"\u003e\n \u003cp\u003eINSERT TABLE 2 ABOUT HERE\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eHaematological parameters are reported in Table 2, with individual changes in haemoglobin shown in Figure 2. Several parameters, including serum haemoglobin, PCV, MCHC, MCH, and MCV, significantly improved in the IG compared to the CG. Specifically, the IG showed increases in haemoglobin (+3.08 g/dL, p = 0.040), PCV (+2.23%, p = 0.017), MCHC (+1.12, p = 0.080), MCH (+1.12, p = 0.080), and MCV (+2.26, p = 0.080). In contrast, the CG showed either minimal changes or non-significant declines in these parameters. Further, the IG also exhibited a significant increase in serum ferritin (Figure 3a). In the IG, 9 out of 12 participants showed an improvement in serum ferritin levels, with an average change of +6.78 \u0026plusmn; 0.9 ng/mL (Pre: 44.76 \u0026plusmn; 29.3, Post: 51.54 \u0026plusmn; 28.4; p \u0026lt; 0.001). Conversely, in the CG (Figure 3b), 10 out of 12 participants exhibited a decline in serum ferritin levels, with an average change of -4.41 \u0026plusmn; 0.0 ng/mL (Pre: 30.31 \u0026plusmn; 20.4, Post: 25.90 \u0026plusmn; 14.8; p = 0.371). The between-group comparison showed a statistically significant difference (p for IG vs. CG = \u0026lt;0.001).\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 624px;\"\u003e\n \u003cp\u003eINSERT FIGURE 3 ABOUT HERE\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eMean vitamin D levels were IG Pre: 30.55\u0026plusmn;10.2 ng/mL. Post: 42.02\u0026plusmn;9.6 ng/mL, Change: +11.47\u0026plusmn;0.6 ng/ml (p \u0026lt; 0.001); CG Pre: 34.55\u0026plusmn;10.8 ng/mL, Post: 33.96\u0026plusmn;10.7 ng/mL, Change: -0.59\u0026plusmn;0.1 ng/ml (p = 0.840); p for IG vs. CG = \u0026lt;0.001). At baseline, seven of 13 IG athletes were deficient in a total of 25-OH vitamin D (below 30 ng/ml), and six out of 13 were sufficient (30-100 ng/mL). At the end of the intervention, only one athlete remained deficient, while 12 out of 13 showed sufficiency. At baseline, six out of 14 CG athletes were deficient in total 25-OH vitamin D, and eight out of 14 were sufficient. By the end of the intervention, seven athletes showed insufficiency.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eTo the extent of our knowledge, this is the first RCT designed to evaluate the effectiveness of culturally tailored, evidence-based, personalized sports dietary advice in improving the nutritional status and dietary intake of national-level track and field athletes in South Asia. The main findings indicate that personalized dietary advice, combined with appropriate micronutrient supplementation, significantly enhances nutritional status, as evidenced by improvements in dietary intake, including energy and micronutrient intake, as well as biochemical parameters such as serum haemoglobin levels, other red blood cell parameters, serum ferritin levels, and total 25-hydroxy vitamin D levels.\u003c/p\u003e \u003cp\u003eThe significant improvements in dietary nutrient intake observed in the IG athletes compared to the CG following the intervention highlight the effectiveness of the dietary modifications implemented. Notably, the enhanced energy intake in the IG is particularly promising for improving athletic performance. This finding is critical, as a considerable proportion of athletes suffer from low energy availability (LEA), which can lead to relative energy deficiency in sport (RED-S). A meta-analysis of 59 studies revealed that 44.7% of 6,118 athletes had LEA, including 44.2% of female and 49.4% of male athletes [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Furthermore, 63.0% of 730 athletes across eight studies were identified as being at risk of RED-S [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Another study reported that 80% of elite Australian female athletes exhibited symptoms of RED-S [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The prevalence of LEA and RED-S could be even higher in developing countries like Sri Lanka, where energy intake is disproportionately low compared to energy expenditure due to factors such as the ongoing economic crisis [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. To address these challenges, our intervention introduced calorie-dense foods and sports supplements to mitigate the risk of LEA among athletes.\u003c/p\u003e \u003cp\u003eA similar trial assessing the effects of an eight-week nutrition education program and controlled dietary modification) found significant reductions in energy deficits, with a 97% increase in daily calorie intake among the IG. Protein intake also increased significantly, meeting 88% of the recommended levels, while carbohydrate intake increased insignificantly to meet 89% of the standards post-intervention [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. These results align with our findings, as IG athletes in this study demonstrated significant increases in protein intake, while carbohydrate intake changes were insignificant. Dietary protein intake in Sri Lanka is notably low, with only 10% of the population's calorie intake derived from proteins [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Our athletes\u0026rsquo; dietary diaries revealed similar patterns, with some meals containing negligible amounts of protein. To address this, we implemented dietary modifications to meet recommended protein intake levels of 1.4\u0026ndash;2.0 g/kg/day as suggested by the latest guidelines [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. These adjustments included distributing protein intake throughout the day. In contrast, carbohydrate intake in the Sri Lankan population typically exceeds nutritional guidelines, contributing approximately 72% of total energy intake [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Consequently, we did not observe a significant increase in carbohydrate intake, likely because the athletes were already consuming an adequate amount.\u003c/p\u003e \u003cp\u003eRegarding fat intake, the IG athletes demonstrated significant increases in PUFAs, as coconut oil was replaced with extra virgin olive oil (EVOO) or other healthier options. Coconut oil, while common in Sri Lankan diets, contains higher levels of saturated fats [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. However, we could not assess changes in saturated fatty acid intake due to the limitations of the Nutri-Survey Software, which lacked this specific component in its analysis. Dietary fibre intake significantly increased among IG athletes, a result of encouraging the inclusion of fruits, nuts, vegetables, and green leafy vegetables in their meals and snacks. Finally, micronutrient intake among IG athletes showed significant improvements compared to the CG and their pre-intervention levels. This was achieved through dietary modifications and the empirical supplementation of multivitamins and multimineral during the 16-week intervention. The increased availability of vitamins and minerals through these strategies addressed the inadequacies typical of Sri Lankan diets [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e], further enhancing the nutritional status of the IG athletes.\u003c/p\u003e \u003cp\u003eIron and vitamin D deficiencies, common among athletes, also merit attention. Iron, a critical component of oxygen transport and energy production, is essential for optimal athletic performance [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. However, a cross-sectional study of 1,190 athletes reported a 19.7% prevalence of iron deficiency, with younger athletes, females, and those with lower VO\u003csub\u003e2\u003c/sub\u003e peak values being most affected [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. This study further reported that athletes with iron deficiency were younger (18.1\u0026thinsp;\u0026plusmn;\u0026thinsp;8.4 vs. 22.8\u0026thinsp;\u0026plusmn;\u0026thinsp;12.1 years, P\u0026thinsp;\u0026lt;\u0026thinsp;0.001), more frequently female (64.5% vs. 26.8%, P\u0026thinsp;\u0026lt;\u0026thinsp;0.001), had lower VO\u003csub\u003e2\u003c/sub\u003e peak values (43.4 vs. 45.6 ml/min/kg, P\u0026thinsp;=\u0026thinsp;0.022), and had a lower proportion of athletes reaching a VO\u003csub\u003e2\u003c/sub\u003e peak of \u0026gt;\u0026thinsp;50 ml/min/kg (8.5% vs. 16.1%, P\u0026thinsp;=\u0026thinsp;0.003). Iron deficiency in athletes can negatively impact various aspects beyond aerobic capacity, including strength, immune function, fatigue, and mood [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. These deficiencies may impair endurance, as well as power, speed, coordination, concentration, recovery, and ultimately, overall performance [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Several studies indicate that a significant number of athletes suffer from vitamin D insufficiency or deficiency [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Hamilton and colleagues found that 84% of 3,422 professional soccer players in Qatar had serum vitamin D levels below 30 ng/mL, with 12% showing severe deficiency (\u0026lt;\u0026thinsp;10 ng/mL) [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Another study revealed that hypovitaminosis D is prevalent among National Basketball Association players, with 32.3% and 41.2% of professional basketball players experiencing vitamin D deficiency (\u0026lt;\u0026thinsp;20 ng/mL) and insufficiency (20\u0026ndash;30 ng/mL), respectively [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Additionally, a large cohort study of college athletes reported that over one-third of players had abnormal vitamin D levels [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. Although we incorporated a random sample of elite and highly trained track and field full-time athletes of both genders, representing the national athletic pool, these athletes exhibited moderate to severe micronutrient deficiencies, as identified through appropriate biochemical testing. Hence, supplementing these commonly deficient micronutrients has been shown to address deficiencies and improve athletic performance [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe current results align with those of previous studies. For instance, a systematic review with meta-analysis (17 studies, 443 participants) indicated beneficial effects of iron supplementation on haemoglobin and ferritin levels among iron-deficient non-anaemic (IDNA) endurance athletes [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. Similarly, DellaValle et al. observed improvements in ferritin levels, energetic efficiency, and lactate response during endurance exercise in an RCT involving IDNA rowers (n\u0026thinsp;=\u0026thinsp;40 women), suggesting that iron supplementation could enhance the benefits of endurance training [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. With regards to vitamin D supplementation, our findings align with previous trials where a double-blind, placebo-controlled study on 2000 IU of vitamin D for three weeks showed positive effects on serum 25(OH)D levels in endurance-trained runners, along with a significant decrease in post-exercise biomarkers [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. The supplemented group demonstrated a significant increase in baseline 25(OH)D levels (34.9\u0026thinsp;\u0026plusmn;\u0026thinsp;4.7 vs. 40.3\u0026thinsp;\u0026plusmn;\u0026thinsp;4.9 ng/mL, p\u0026thinsp;=\u0026thinsp;0.02) and a higher post-intervention 25(OH)D level compared to placebo (40.3\u0026thinsp;\u0026plusmn;\u0026thinsp;4.9 vs. 31.8\u0026thinsp;\u0026plusmn;\u0026thinsp;4.2 ng/mL, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). This study demonstrated that a personalized approach is more effective than a one-size-fits-all approach in restoring adequate vitamin D levels in athletes [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e].\u003c/p\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003eStrengths and limitations\u003c/h2\u003e \u003cp\u003eThe main strength of this study is its personalized approach to both diet and supplementation. This distinguishes it from previous studies that typically focused on a one-size-fits-all intervention, such as administering the same protein dose or one vitamin supplement to all participants. In contrast, we carefully tailored dietary advice and supplement doses for each individual based on available evidence, taking into account the specific needs of each athlete. For example, protein supplements were provided only when individuals had difficulty meeting their protein requirements through food, and vitamin D supplementation was adjusted according to the severity of the deficiency, with higher doses for those with severe deficiencies and lower doses for those with insufficiency. This personalized approach ensured that the intervention was both effective and practical, leading to significant improvements in key biomarkers, including Hb, RBC parameters, serum ferritin, and vitamin D levels, as demonstrated by post-intervention biochemical tests.\u003c/p\u003e \u003cp\u003eDespite these strengths, the study has several limitations including the small sample size which may affect the generalizability of findings. Furthermore, due to the nature of the trial, we could not directly measure participant compliance with the intervention, which could have influenced the outcomes. Another limitation was the inability to measure the full range of serum micronutrient levels, including calcium, vitamin A, and vitamin E, as these tests were expensive. Additionally, while serum ferritin is a common marker for iron status, its interpretation can be complicated by the inflammatory status of athletes, which may fluctuate due to intense physical training [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. This could have impacted the accuracy of the serum ferritin results, as ferritin levels may appear normal despite depleted iron stores during periods of systemic inflammation [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. Future studies could consider including larger sample sizes, employing more precise measures of compliance, and expanding the range of micronutrient assessments to obtain a more complete picture of nutritional status. It would also be valuable to replicate this intervention in diverse athlete populations after proper screening for nutritional and training status to validate these findings in broader contexts. To further enhance the impact of personalized nutrition interventions, future research could also explore the long-term effects of sustained personalized sports nutrition interventions on athletic performance and health.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn conclusion, this study demonstrates the effectiveness of a culturally appropriate, evidence-based, personalized dietary advice in addressing micronutrient deficiencies and improving the nutritional status, and dietary intake among track and field athletes. The intervention, based on individual dietary intakes and biochemical parameters, led to significant improvements in key biomarkers such as Hb, serum ferritin, and vitamin D levels. This trial provides valuable insights into the benefits of personalized nutrition in enhancing athlete health and performance.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eBMI: Body Mass Index; CG: Control Group; Change: Change from Pre to Post; CLIA: Chemiluminescence Immunoassay; Dietary Fibre: Dietary Fibre; FBC: Full Blood Count; FM: Fat Mass; FFM: Fat-Free Mass; g/kg/day: Grams per Kilogram per Day; Haemoglobin (Hb): Haemoglobin; IG: Intervention Group; IU: International Units; kcal: Kilocalories; LBM: Lean Body Mass; MCH: Mean Corpuscular Haemoglobin; MCHC: Mean Corpuscular Haemoglobin Concentration; MCV: Mean Corpuscular Volume; PCV: Packed Cell Volume; Polyunsaturated Fatty Acids (PUFA): Polyunsaturated Fatty Acids; Pre: Pre-intervention; Post: Post-intervention; RCT: Randomized Controlled Trial.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe express our gratitude to all the athletes who participated in this trial, as well as to all other contributors who helped improve the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo funding was received for conducting this study, however, a part of the fees for biochemical tests were covered by Nawaloka Hospitals PLC, Sri Lanka.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflicts of interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical approval\u003c/strong\u003e \u003cstrong\u003eand consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe qualitative study used in the multi-modal approach during the development of the questionnaire was conducted in accordance with the standards set by the Declaration of Helsinki. Ethical approval was obtained from the Ethics Review Committee of the Faculty of Medicine, University of Peradeniya, Sri Lanka, prior to conducting the study (Ref No. 2022/EC/66). All participants provided written informed consent to participate in the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contribution\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRJ conceived and designed the study. RJ and KW were involved in data collection and analysis. RJ and KW contributed to drafting the manuscript. NSK, TM, IN and APH, as supervisory team members, participated in the revision of the paper. All authors carefully reviewed and approved the final version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eThe full trial protocol access\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eResearchGate:https://www.researchgate.net/publication/382314659_The_effects_of_a_nutritional_intervention_on_the_sports_nutrition_knowledge_and_nutritional_\u003cbr\u003estatus_of_elite_athletes_protocol_for_a_randomized_controlled_trial.\u003c/p\u003e\n\u003cp\u003eBibliography: Jayawardena R, Weerasinghe K, Nanayakkara I, Madhujith T, Hills AP, Kalupahana NS. The effects of a nutritional intervention on the\u0026nbsp;\u003cbr\u003esports nutrition knowledge and nutritional status of elite athletes: protocol for a randomized controlled trial. 2024.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eAmawi A, AlKasasbeh W, Jaradat M, Almasri A, Alobaidi S, Hammad AA, et al. 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Nutrients. 2019;11(10).\u003c/li\u003e\n \u003cli\u003eHamilton B, Whiteley R, Farooq A, Chalabi H. Vitamin D concentration in 342 professional football players and association with lower limb isokinetic function. J Sci Med Sport. 2014;17(1):139-43.\u003c/li\u003e\n \u003cli\u003eGrieshober JA, Mehran N, Photopolous C, Fishman M, Lombardo SJ, Kharrazi FD. Vitamin D Insufficiency Among Professional Basketball Players: A Relationship to Fracture Risk and Athletic Performance. Orthop J Sports Med. 2018;6(5):2325967118774329.\u003c/li\u003e\n \u003cli\u003eVillacis D, Yi A, Jahn R, Kephart CJ, Charlton T, Gamradt SC, et al. Prevalence of Abnormal Vitamin D Levels Among Division I NCAA Athletes. Sports Health. 2014;6(4):340-7.\u003c/li\u003e\n \u003cli\u003eJayawardena R, Weerasinghe K, Madhujith T, Hills AP, Kalupahana N. Perceptions of the importance of sports nutrition knowledge and barriers in implementing them: a qualitative study among track and field stakeholders in Sri Lanka. BMC Nutr. 2024;10(1):17.\u003c/li\u003e\n \u003cli\u003eBurden RJ, Morton K, Richards T, Whyte GP, Pedlar CR. Is iron treatment beneficial in, iron-deficient but non-anaemic (IDNA) endurance athletes? A systematic review and meta-analysis. Br J Sports Med. 2015;49(21):1389-97.\u003c/li\u003e\n \u003cli\u003eDellaValle DM, Haas JD. Iron supplementation improves energetic efficiency in iron-depleted female rowers. Med Sci Sports Exerc. 2014;46(6):1204-15.\u003c/li\u003e\n \u003cli\u003eŻebrowska A, Sadowska-Krępa E, Stanula A, Waśkiewicz Z, Łakomy O, Bezuglov E, et al. The effect of vitamin D supplementation on serum total 25(OH) levels and biochemical markers of skeletal muscles in runners. J Int Soc Sports Nutr. 2020;17(1):18.\u003c/li\u003e\n \u003cli\u003eTuma C, Schick A, Pommerening N, Braun H, Thevis M. Effects of an Individualized vs. Standardized Vitamin D Supplementation on the 25(OH)D Level in Athletes. Nutrients. 2023;15(22).\u003c/li\u003e\n \u003cli\u003eCerqueira \u0026Eacute;, Marinho DA, Neiva HP, Louren\u0026ccedil;o O. Inflammatory Effects of High and Moderate Intensity Exercise-A Systematic Review. Front Physiol. 2019;10:1550.\u003c/li\u003e\n \u003cli\u003eDignass A, Farrag K, Stein J. Limitations of Serum Ferritin in Diagnosing Iron Deficiency in Inflammatory Conditions. Int J Chronic Dis. 2018;2018:9394060.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables 1 to 2 are available in the Supplementary Files section\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-sports-science-medicine-and-rehabilitation","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ssmr","sideBox":"Learn more about [BMC Sports Science, Medicine and Rehabilitation](http://bmcsportsscimedrehabil.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ssmr/default.aspx","title":"BMC Sports Science, Medicine and Rehabilitation","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Dietary intake, Personalized nutrition, Track and field, Nutritional status, Sri Lanka","lastPublishedDoi":"10.21203/rs.3.rs-5789887/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5789887/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground: \u003c/strong\u003eOptimal nutrition is vital for recovery, performance, and well-being of athletes. However, Sri Lankan track and field athletes often fall short of dietary recommendations due to the lack of personalized nutrition guidance. This study evaluated the effectiveness of culturally appropriate, evidence-based, personalized dietary advice on the nutritional status of these athletes.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods: \u003c/strong\u003eThis 16-week parallel-group randomized controlled trial included 30 national-level track and field athletes (15 in the intervention group [IG], 15 in the control group [CG]). The IG received personalized dietary prescriptions based on detailed nutritional assessments, while the CG received no advice. Outcomes included dietary intake, assessed via seven-day food diaries, and biochemical parameters measured using standard techniques.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e Twenty-seven athletes (IG: 13, CG: 14) completed the study. The IG showed significant increases in energy intake (Pre: 2766.0 ± 494.0 kcal, Post: 3972.9 ± 934.4 kcal, Change: +1206.9 kcal; p = 0.007) compared to the CG (Pre: 2733.7 ± 635.5 kcal, Post: 2676.5 ± 319.2 kcal, Change: -57.2 kcal; p = 0.739; p for IG vs. CG = 0.004). Protein intake also improved significantly in the IG (Pre: 95.56 ± 30.2 g, Post: 116.81 ± 41.8 g, Change: +21.25 g; p = 0.003) versus the CG (Pre: 94.54 ± 32.8 g, Post: 84.24 ± 16.4 g, Change: -10.30 g; p = 0.162; p for IG vs. CG = 0.001). The IG exhibited improved vitamin and mineral intakes, and serum vitamin D levels in the IG increased significantly (Pre: 30.55 ± 10.2 ng/ml, Post: 42.02 ± 9.6 ng/ml; Change: +11.47 ± 0.6 ng/ml; p \u0026lt; 0.001), while the CG showed no change. Serum ferritin levels also increased in the IG (Pre: 44.76 ± 29.3 ng/ml, Post: 51.54 ± 28.4 ng/ml, Change: +6.78 ± 0.9 ng/ml; p \u0026lt; 0.001), along with positive changes in haemoglobin and other haematological parameters.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions:\u003c/strong\u003e A culturally appropriate, personalized dietary prescription significantly improved the nutritional status among Sri Lankan track and field athletes.\u003c/p\u003e","manuscriptTitle":"Culturally appropriate, evidence-based, personalized dietary advice to improve the nutritional status of track and field athletes: a randomized controlled trial","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-01-13 10:09:25","doi":"10.21203/rs.3.rs-5789887/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-01-22T09:46:23+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-01-09T12:32:49+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-01-09T12:32:06+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Sports Science, Medicine and Rehabilitation","date":"2025-01-08T14:13:45+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-sports-science-medicine-and-rehabilitation","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ssmr","sideBox":"Learn more about [BMC Sports Science, Medicine and Rehabilitation](http://bmcsportsscimedrehabil.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ssmr/default.aspx","title":"BMC Sports Science, Medicine and Rehabilitation","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"40f27518-f98f-4ac3-a58e-60cb7343a882","owner":[],"postedDate":"January 13th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-01-27T05:23:14+00:00","versionOfRecord":[],"versionCreatedAt":"2025-01-13 10:09:25","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5789887","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5789887","identity":"rs-5789887","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}