Public Interest in Third-Party Tested Dietary Supplements Before and After the Covid-19 Pandemic

Public Interest in Third-Party Tested Dietary Supplements Before and After the Covid-19 Pandemic | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Public Interest in Third-Party Tested Dietary Supplements Before and After the Covid-19 Pandemic Madison Contor, Victor Ching This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8286819/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Introduction: Dietary supplements are widely used in the United States but remain lightly regulated, raising concerns about contaminants and inconsistent potency. Independent, third-party testing offers a way to assure quality and safety, yet little is known about public interest in such testing. This study examined trends in U.S. interest in third-party tested supplements before and after the Covid-19 pandemic. Methods Google Trends data from January 2018 to August 2025 were analyzed for terms related to third-party testing (“third party tested,” “USP verified,” “NSF certified”) and for common non-third party supplements (“vitamin D,” “multivitamins,” “fish oil”). Relative search volume was normalized to February 2019. Growth trajectories were compared using Welch’s t-tests, Mann–Whitney U tests, and ordinary least squares regression with time-by-group interaction terms. Results Interest in third-party tested supplements rose sharply beginning in 2021, reaching nearly 800% growth by 2025 compared with < 100% growth for non-third party terms. Regression analysis revealed a significantly steeper growth trajectory for third-party terms (β = 0.0089, p 1,500%), while “NSF certified” and “USP verified” showed more modest but consistent growth. Discussion/Conclusion: Public interest in third-party tested supplements has accelerated beyond general supplement interest since the Covid-19 pandemic, reflecting rising consumer concern with safety and quality. These findings highlight an emerging shift in consumer priorities with implications for public health messaging, regulatory policy, and industry practices. Future research should examine whether increased interest translates into purchasing behavior and evolving regulatory frameworks. Dietary suppleµents third-party tested Google Trends quality assurance Figures Figure 1 Figure 2 Introduction Dietary supplements are widely used in the United States, with nearly 60% reporting using them between 2017 and 2020; a number which has likely since grown [ 1 ]. As consumer use has expanded, so has the body of research examining the potential health benefits of dietary supplements. Yet, in the U.S., supplements remain lightly regulated and are not subject to mandatory testing for purity, potency, or contaminants such as heavy metals, molds, and pesticides [ 2 ]. Numerous studies have demonstrated alarmingly high rates of such contaminants in commercially available products, raising significant concerns about consumer safety [ 3 – 5 ]. Independent, third-party testing provides a pathway for manufacturers to guarantee product quality and safety. However, many popular supplements on the market have not undergone third-party testing. This raises important questions about public awareness and consumer demand: Is the public aware of the value of third-party testing? Has interest in such products shifted in recent years, and if so, when? Identifying these patterns may shed light on broader public health issues. Despite the importance, there is currently no research that specifically examines public interest in third-party tested supplements among the general U.S. population. Existing studies have largely focused on competitive athletes, who may face unique pressures and motivations regarding supplement safety, leaving a gap in understanding broader consumer attitudes and behaviors. Addressing this gap is essential to assist in developing effective public health communication strategies and for guiding the supplement industry in meeting consumer expectations. Exploring public awareness and interest in third-party testing is both timely and relevant, with implications for consumer safety, public health, policy, and industry practices. Findings from this could inform communication strategies and guide the supplement industry in meeting evolving consumer expectations. Previous evidence suggests that supplement use and interest rose sharply during the Covid-19 pandemic [ 6 ]. If a similar increase in attention toward third-party tested supplements is observed, understanding whether this occurred concurrently with or after the general rise in supplement usage will be important for interpreting consumer behavior. This paper aims to explore: How public interest in third-party tested supplements has evolved in recent years, particularly in the period leading up to and following the Covid-19 pandemic. If a significant shift in interest has occurred, when this change can be identified Materials and Methods Google Trends is a publicly available tool that quantifies and visualizes the relative popularity of Google search engine inputs. Results can be filtered for timeframe, geographic region, and category (e.g., “Vitamins and Supplements”). Results are presented as normalized relative search volume (RSV) values scaled from 0 to 100, with 100 representing the highest search volume. This can serve as a surrogate marker for relative public interest in the search terms. To compare growth between third-party tested and non-third party tested supplements, search terms were selected for each group and then data analysis was carried out between them as well as for each individual term. For the third-party tested supplements group, the following search terms were included: Third party tested, USP verified, and NSF certified. These terms were selected as NSF and USP are among the most recognized third-party testing organizations in the United States [ 7 ]. Terms for non-third party tested supplements included: vitamin D , multivitamin s, and fish oil . These terms were selected as these are among the most frequently used dietary supplement in the United States and could therefore serve as a surrogate control for general supplement interest [ 8 ]. Comparing these two groups of search terms allowed us to assess whether public interest in third-party tested supplements grew over time or simply mirrored general supplement interest. The custom timeframe selected was January 2018 through August 2025. This range enabled analysis beginning before the Covid-19 pandemic, as previous studies have shown vitamin and supplement interest shifts around the pandemic [ 6 ]. Searches were restricted to the United States, and the category filter “Vitamins and Supplements” was engaged to reduce confounding from unrelated search contexts. Because Google Trends permits a maximum of five terms per search, two separate queries were performed: one for third-party terms and one for non–third-party terms. To ensure the resultant values between the two groups were comparable despite their different absolute scales, all time series were normalized relative to a fixed baseline. The baseline period selected was February 1–28, 2019, because some terms exhibited RSVs of 0 prior to this point, precluding earlier normalization. Average monthly RSVs for each term were calculated and transformed into a percent change relative to baseline. A value of zero indicates a search interest equal to that in February 2019, while positive values indicate a higher relative interest and negative values indicate a lower relative. To compare growth trajectories between third-party and non-third party tested terms, Welch’s t-tests were conducted to assess mean differences and supplemented by Mann–Whitney U tests to account for potentially non-normal distributions. Effect sizes were estimated using Cohen’s d . In addition, an ordinary least squares regression model was fitted with an interaction between time and group (third-party vs. non-third party) to test whether growth slopes differed over time. All analyses were conducted in August 2025 in Python (version 3.x) using Google Colaboratory. Data manipulation and visualization were performed with pandas and matplotlib, while statistical analyses were completed using SciPy, statsmodels, and pingouin. Results The average percent growth for the third-party tested supplements terms began to climb significantly in 2021, reaching nearly 800% growth in 2025. In contrast, the non-third party tested supplements exhibited an overall percent growth of less than 100% from 2018 to 2025 [Figure 1 ]. Regression analysis revealed a significant interaction between time and third-party testing status (β = 0.0089, p < 0.001), revealing a significantly steeper growth interest for third-party tested supplements than for non-third-party supplements. While non-third-party supplements showed only modest increases over time (β = 0.0043, p < 0.001), interest in third-party terms accelerated rapidly, surpassing non-third-party levels after 2022 and continuing to diverge. The model explained 88.8% of the variance (R² = 0.888), underscoring the robustness of this trend. Welch’s t-tests revealed that growth of search interest for the third-party tested terms was significantly greater than the non-third party tested terms across the entire timeframe ( t (180) = − 15.69, p < 0.001). A Mann-Whitney U test confirmed these findings to be robust ( U = 645, p < 0.001). The effect size was also very large (Cohen’s d = -2.31), revealing that the difference in growth between the two groups was not only statistically significant but also of substantial practical magnitude. At the individual term level, “third party tested” exhibited the steepest increase, surpassing 1,500% growth by 2025, while “NSF certified” and “USP verified” showed more modest but consistent gains [Figure 2 ]. In contrast, common supplement terms such as vitamin D, multivitamins, and fish oil remained relatively stable over the study period. Discussion The growing popularity of third-party tested supplements in recent years reflects a meaningful shift in how Americans view the wellness industry. Results indicate that interest in third-party tested supplements has grown significantly beyond interest in non–third party tested supplements, suggesting that consumers are not merely becoming more invested in supplements, but specifically in the quality and safety assurances provided by third-party testing. This trend implies rising public awareness of potential contaminants, inconsistent potencies, and undeclared ingredients in dietary supplements. One possible explanation for this shift is the increased media and social media coverage highlighting contamination risks, lack of ingredient transparency, and general safety concerns within the supplement industry. Such coverage may be shaping consumer expectations and driving demand for greater accountability in supplement labeling and manufacturing. Among individual search terms, “third party tested” vitamins and supplements exhibited the greatest growth, surpassing more specific terms such as “NSF certified” and “USP verified.” This pattern suggests that while consumers are increasingly aware of third-party testing as a concept, there is comparatively less recognition—or growth in interest—in specific certification bodies or organizations. Whether this consumer-driven momentum will eventually prompt stronger FDA regulations or lead the supplement industry itself to expand third-party testing in response to market pressures remains an open question. Continued monitoring of consumer interest and industry practices will be essential for understanding how this trend evolves and what implications it may hold for public health, policy, and industry standards. Future research could investigate how increased consumer demand for third-party tested supplements translates into actual purchasing behaviors and long-term health outcomes. Surveys and market analyses could assess whether consumers who search for or express interest in “third party tested” supplements ultimately choose these products over non-certified alternatives. Additionally, studies could explore the relative influence of different certification labels (e.g., NSF, USP) on consumer trust and decision-making, especially as public familiarity with specific organizations grows. Finally, policy-focused studies should track how these consumer-driven trends interact with evolving regulatory frameworks, providing insight into whether grassroots demand can meaningfully shape federal oversight and industry standards in the years ahead. Declarations Data Availability Statement: All data used in this study were sourced from Google Trends, an openly available online data platform. Google Trends data can be accessed at https://trends.google.com. The full dataset extracted for this study, including weekly search volume indices and search parameters, has been deposited in two supplementary files accompanying this manuscript entitled “Third-Party Tested Terms Google Trends Data” and “Non Third-Party Tested Terms Google Trends Data.” No proprietary or restricted data were used. Competing Interests: The authors declare no competing interests. This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Funding Statement: The authors declare this work did not receive any funding. Author Contributions: M.C. conceptualized the basis of the research, developed the methodology, curated data, carried out formal analysis, wrote the original draft, and contributed to edits. V.C. conceptualized the basis of the research, carried out writing and reviewing of the paper, and supervised. References Mishra S, Gahche JJ, Ogden CL, Dimeler M, Potischman N, Ahluwalia N. Dietary supplement use in the United States: National Health and Nutrition Examination Survey, 2017–March 2020. National Health Statistics Reports; 2023. pp. 1–12. 183. Cohen PA, Avigan MI, Weingart SN. What should dietary supplement oversight look like in the US? AMA J Ethics. 2022;24(5):E441–8. https://doi.org/10.1001/amajethics.2022.441 . Gardener H, Bowen J, Callan SP. Heavy metals and phthalate contamination in prenatal vitamins and folic acid supplements. Environ Res. 2025;274:121255. https://doi.org/10.1016/j.envres.2025.121255 . Crighton E, Coghlan ML, Farrington R, Hoban CL, Power MWP, Nash C, et al. Toxicological screening and DNA sequencing detects contamination and adulteration in regulated herbal medicines and supplements for diet, weight loss, and cardiovascular health. J Pharm Biomed Anal. 2019;176:112834. https://doi.org/10.1016/j.jpba.2019.112834 . White CM. Dietary supplements pose real dangers to patients. Ann Pharmacother. 2020;54(8):815–9. https://doi.org/10.1177/1060028019900504 . Lin LY, Husnayain A, Chen YT, Kuo CY. The association between interest of nutritional supplements and COVID-19 pandemic: Evidence from Google Trends. BMC Public Health. 2024;24:109. https://doi.org/10.1186/s12889-023-17607-2 . Akabas SR, Vannice G, Atwater JB, Cooperman T, Cotter R, Thomas L. Quality certification programs for dietary supplements. J Acad Nutr Dietetics. 2016;116(9):1370–9. https://doi.org/10.1016/j.jand.2016.05.005 . Mishra S, Stierman B, Gahche JJ, Potischman N. (2021). Dietary supplement use among adults: United States, 2017–2018. NCHS Data Brief, (399), 1–8. Additional Declarations No competing interests reported. Supplementary Files ThirdPartyTestedTermsGoogleTrendsData.pdf NonThirdPartyTestedTermsGoogleTrendsData.pdf Cite Share Download PDF Status: Posted Version 1 posted 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-8286819","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":568850362,"identity":"f0a63e8a-3cef-4f76-b332-59ce57222ee5","order_by":0,"name":"Madison 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1","display":"","copyAsset":false,"role":"figure","size":72144,"visible":true,"origin":"","legend":"\u003cp\u003eAverage percent growth of grouped third-party and non-third party tested terms from January 2018- August 2025 normalized from February 2019\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8286819/v1/092d4beee6eae91e83f0ad8d.png"},{"id":99494306,"identity":"3a6dc4bd-21c8-4cf8-b216-9078d7dde6de","added_by":"auto","created_at":"2026-01-05 05:54:54","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":104484,"visible":true,"origin":"","legend":"\u003cp\u003ePercent growth of each term from January 2018- August 2025 normalized from February 2019.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8286819/v1/d0f73ac36fa00112214a5ac1.png"},{"id":103049763,"identity":"9628e9d0-6d4c-45d7-9d75-7ec8064ff7fa","added_by":"auto","created_at":"2026-02-20 07:45:46","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":450904,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8286819/v1/23c04796-c877-4471-97be-11ae8a97c791.pdf"},{"id":99494300,"identity":"3c4c8137-5a6a-40b3-9dcd-99d5a3bc7bc3","added_by":"auto","created_at":"2026-01-05 05:54:53","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":121454,"visible":true,"origin":"","legend":"","description":"","filename":"ThirdPartyTestedTermsGoogleTrendsData.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8286819/v1/cc057def51a364faf822ea3e.pdf"},{"id":99494297,"identity":"718d334f-9856-4b31-ac18-1f7eb14e4cf3","added_by":"auto","created_at":"2026-01-05 05:54:53","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":120370,"visible":true,"origin":"","legend":"","description":"","filename":"NonThirdPartyTestedTermsGoogleTrendsData.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8286819/v1/997714960033661c16cf0a66.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Public Interest in Third-Party Tested Dietary Supplements Before and After the Covid-19 Pandemic","fulltext":[{"header":"Introduction","content":"\u003cp\u003eDietary supplements are widely used in the United States, with nearly 60% reporting using them between 2017 and 2020; a number which has likely since grown [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. As consumer use has expanded, so has the body of research examining the potential health benefits of dietary supplements. Yet, in the U.S., supplements remain lightly regulated and are not subject to mandatory testing for purity, potency, or contaminants such as heavy metals, molds, and pesticides [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Numerous studies have demonstrated alarmingly high rates of such contaminants in commercially available products, raising significant concerns about consumer safety [\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIndependent, third-party testing provides a pathway for manufacturers to guarantee product quality and safety. However, many popular supplements on the market have not undergone third-party testing. This raises important questions about public awareness and consumer demand: Is the public aware of the value of third-party testing? Has interest in such products shifted in recent years, and if so, when? Identifying these patterns may shed light on broader public health issues.\u003c/p\u003e \u003cp\u003eDespite the importance, there is currently no research that specifically examines public interest in third-party tested supplements among the general U.S. population. Existing studies have largely focused on competitive athletes, who may face unique pressures and motivations regarding supplement safety, leaving a gap in understanding broader consumer attitudes and behaviors. Addressing this gap is essential to assist in developing effective public health communication strategies and for guiding the supplement industry in meeting consumer expectations.\u003c/p\u003e \u003cp\u003eExploring public awareness and interest in third-party testing is both timely and relevant, with implications for consumer safety, public health, policy, and industry practices. Findings from this could inform communication strategies and guide the supplement industry in meeting evolving consumer expectations. Previous evidence suggests that supplement use and interest rose sharply during the Covid-19 pandemic [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. If a similar increase in attention toward third-party tested supplements is observed, understanding whether this occurred concurrently with or after the general rise in supplement usage will be important for interpreting consumer behavior.\u003c/p\u003e \u003cp\u003eThis paper aims to explore:\u003c/p\u003e \u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eHow public interest in third-party tested supplements has evolved in recent years, particularly in the period leading up to and following the Covid-19 pandemic.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eIf a significant shift in interest has occurred, when this change can be identified\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003eGoogle Trends is a publicly available tool that quantifies and visualizes the relative popularity of Google search engine inputs. Results can be filtered for timeframe, geographic region, and category (e.g., \u0026ldquo;Vitamins and Supplements\u0026rdquo;). Results are presented as normalized relative search volume (RSV) values scaled from 0 to 100, with 100 representing the highest search volume. This can serve as a surrogate marker for relative public interest in the search terms.\u003c/p\u003e \u003cp\u003eTo compare growth between third-party tested and non-third party tested supplements, search terms were selected for each group and then data analysis was carried out between them as well as for each individual term. For the third-party tested supplements group, the following search terms were included: \u003cem\u003eThird party tested, USP verified, and NSF certified.\u003c/em\u003e These terms were selected as NSF and USP are among the most recognized third-party testing organizations in the United States [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Terms for non-third party tested supplements included: \u003cem\u003evitamin D\u003c/em\u003e, \u003cem\u003emultivitamin\u003c/em\u003es, and \u003cem\u003efish oil\u003c/em\u003e. These terms were selected as these are among the most frequently used dietary supplement in the United States and could therefore serve as a surrogate control for general supplement interest [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Comparing these two groups of search terms allowed us to assess whether public interest in third-party tested supplements grew over time or simply mirrored general supplement interest.\u003c/p\u003e \u003cp\u003eThe custom timeframe selected was January 2018 through August 2025. This range enabled analysis beginning before the Covid-19 pandemic, as previous studies have shown vitamin and supplement interest shifts around the pandemic [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Searches were restricted to the United States, and the category filter \u0026ldquo;Vitamins and Supplements\u0026rdquo; was engaged to reduce confounding from unrelated search contexts.\u003c/p\u003e \u003cp\u003eBecause Google Trends permits a maximum of five terms per search, two separate queries were performed: one for third-party terms and one for non\u0026ndash;third-party terms. To ensure the resultant values between the two groups were comparable despite their different absolute scales, all time series were normalized relative to a fixed baseline. The baseline period selected was February 1\u0026ndash;28, 2019, because some terms exhibited RSVs of 0 prior to this point, precluding earlier normalization. Average monthly RSVs for each term were calculated and transformed into a percent change relative to baseline. A value of zero indicates a search interest equal to that in February 2019, while positive values indicate a higher relative interest and negative values indicate a lower relative.\u003c/p\u003e \u003cp\u003eTo compare growth trajectories between third-party and non-third party tested terms, Welch\u0026rsquo;s t-tests were conducted to assess mean differences and supplemented by Mann\u0026ndash;Whitney U tests to account for potentially non-normal distributions. Effect sizes were estimated using Cohen\u0026rsquo;s \u003cem\u003ed\u003c/em\u003e. In addition, an ordinary least squares regression model was fitted with an interaction between time and group (third-party vs. non-third party) to test whether growth slopes differed over time.\u003c/p\u003e \u003cp\u003eAll analyses were conducted in August 2025 in Python (version 3.x) using Google Colaboratory. Data manipulation and visualization were performed with pandas and matplotlib, while statistical analyses were completed using SciPy, statsmodels, and pingouin.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eThe average percent growth for the third-party tested supplements terms began to climb significantly in 2021, reaching nearly 800% growth in 2025. In contrast, the non-third party tested supplements exhibited an overall percent growth of less than 100% from 2018 to 2025 [Figure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e]. Regression analysis revealed a significant interaction between time and third-party testing status (β\u0026thinsp;=\u0026thinsp;0.0089, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), revealing a significantly steeper growth interest for third-party tested supplements than for non-third-party supplements. While non-third-party supplements showed only modest increases over time (β\u0026thinsp;=\u0026thinsp;0.0043, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), interest in third-party terms accelerated rapidly, surpassing non-third-party levels after 2022 and continuing to diverge. The model explained 88.8% of the variance (R\u0026sup2; = 0.888), underscoring the robustness of this trend.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWelch\u0026rsquo;s t-tests revealed that growth of search interest for the third-party tested terms was significantly greater than the non-third party tested terms across the entire timeframe (\u003cem\u003et\u003c/em\u003e(180)\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;15.69, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). A Mann-Whitney U test confirmed these findings to be robust (\u003cem\u003eU\u003c/em\u003e\u0026thinsp;=\u0026thinsp;645, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The effect size was also very large (Cohen\u0026rsquo;s \u003cem\u003ed\u003c/em\u003e = -2.31), revealing that the difference in growth between the two groups was not only statistically significant but also of substantial practical magnitude.\u003c/p\u003e \u003cp\u003eAt the individual term level, \u0026ldquo;third party tested\u0026rdquo; exhibited the steepest increase, surpassing 1,500% growth by 2025, while \u0026ldquo;NSF certified\u0026rdquo; and \u0026ldquo;USP verified\u0026rdquo; showed more modest but consistent gains [Figure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e]. In contrast, common supplement terms such as vitamin D, multivitamins, and fish oil remained relatively stable over the study period.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe growing popularity of third-party tested supplements in recent years reflects a meaningful shift in how Americans view the wellness industry. Results indicate that interest in third-party tested supplements has grown significantly beyond interest in non\u0026ndash;third party tested supplements, suggesting that consumers are not merely becoming more invested in supplements, but specifically in the quality and safety assurances provided by third-party testing. This trend implies rising public awareness of potential contaminants, inconsistent potencies, and undeclared ingredients in dietary supplements.\u003c/p\u003e \u003cp\u003eOne possible explanation for this shift is the increased media and social media coverage highlighting contamination risks, lack of ingredient transparency, and general safety concerns within the supplement industry. Such coverage may be shaping consumer expectations and driving demand for greater accountability in supplement labeling and manufacturing.\u003c/p\u003e \u003cp\u003eAmong individual search terms, \u0026ldquo;third party tested\u0026rdquo; vitamins and supplements exhibited the greatest growth, surpassing more specific terms such as \u0026ldquo;NSF certified\u0026rdquo; and \u0026ldquo;USP verified.\u0026rdquo; This pattern suggests that while consumers are increasingly aware of third-party testing as a concept, there is comparatively less recognition\u0026mdash;or growth in interest\u0026mdash;in specific certification bodies or organizations.\u003c/p\u003e \u003cp\u003eWhether this consumer-driven momentum will eventually prompt stronger FDA regulations or lead the supplement industry itself to expand third-party testing in response to market pressures remains an open question. Continued monitoring of consumer interest and industry practices will be essential for understanding how this trend evolves and what implications it may hold for public health, policy, and industry standards.\u003c/p\u003e \u003cp\u003eFuture research could investigate how increased consumer demand for third-party tested supplements translates into actual purchasing behaviors and long-term health outcomes. Surveys and market analyses could assess whether consumers who search for or express interest in \u0026ldquo;third party tested\u0026rdquo; supplements ultimately choose these products over non-certified alternatives. Additionally, studies could explore the relative influence of different certification labels (e.g., NSF, USP) on consumer trust and decision-making, especially as public familiarity with specific organizations grows. Finally, policy-focused studies should track how these consumer-driven trends interact with evolving regulatory frameworks, providing insight into whether grassroots demand can meaningfully shape federal oversight and industry standards in the years ahead.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData Availability Statement:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data used in this study were sourced from Google Trends, an openly available online data platform. Google Trends data can be accessed at https://trends.google.com. The full dataset extracted for this study, including weekly search volume indices and search parameters, has been deposited in two supplementary files accompanying this manuscript entitled \u0026ldquo;Third-Party Tested Terms Google Trends Data\u0026rdquo; and \u0026ldquo;Non Third-Party Tested Terms Google Trends Data.\u0026rdquo; No proprietary or restricted data were used.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests. This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding Statement:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare this work did not receive any funding.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eM.C. conceptualized the basis of the research, developed the methodology, curated data, carried out formal analysis, wrote the original draft, and contributed to edits.\u003c/p\u003e\n\u003cp\u003eV.C. conceptualized the basis of the research, carried out writing and reviewing of the paper, and supervised.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eMishra S, Gahche JJ, Ogden CL, Dimeler M, Potischman N, Ahluwalia N. Dietary supplement use in the United States: National Health and Nutrition Examination Survey, 2017\u0026ndash;March 2020. National Health Statistics Reports; 2023. pp. 1\u0026ndash;12. 183.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCohen PA, Avigan MI, Weingart SN. What should dietary supplement oversight look like in the US? AMA J Ethics. 2022;24(5):E441\u0026ndash;8. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1001/amajethics.2022.441\u003c/span\u003e\u003cspan address=\"10.1001/amajethics.2022.441\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGardener H, Bowen J, Callan SP. Heavy metals and phthalate contamination in prenatal vitamins and folic acid supplements. Environ Res. 2025;274:121255. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.envres.2025.121255\u003c/span\u003e\u003cspan address=\"10.1016/j.envres.2025.121255\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCrighton E, Coghlan ML, Farrington R, Hoban CL, Power MWP, Nash C, et al. Toxicological screening and DNA sequencing detects contamination and adulteration in regulated herbal medicines and supplements for diet, weight loss, and cardiovascular health. J Pharm Biomed Anal. 2019;176:112834. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jpba.2019.112834\u003c/span\u003e\u003cspan address=\"10.1016/j.jpba.2019.112834\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWhite CM. Dietary supplements pose real dangers to patients. Ann Pharmacother. 2020;54(8):815\u0026ndash;9. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1177/1060028019900504\u003c/span\u003e\u003cspan address=\"10.1177/1060028019900504\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLin LY, Husnayain A, Chen YT, Kuo CY. The association between interest of nutritional supplements and COVID-19 pandemic: Evidence from Google Trends. BMC Public Health. 2024;24:109. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1186/s12889-023-17607-2\u003c/span\u003e\u003cspan address=\"10.1186/s12889-023-17607-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAkabas SR, Vannice G, Atwater JB, Cooperman T, Cotter R, Thomas L. Quality certification programs for dietary supplements. J Acad Nutr Dietetics. 2016;116(9):1370\u0026ndash;9. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jand.2016.05.005\u003c/span\u003e\u003cspan address=\"10.1016/j.jand.2016.05.005\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMishra S, Stierman B, Gahche JJ, Potischman N. (2021). Dietary supplement use among adults: United States, 2017\u0026ndash;2018. NCHS Data Brief, (399), 1\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Dietary suppleµents, third-party tested, Google Trends, quality assurance","lastPublishedDoi":"10.21203/rs.3.rs-8286819/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8286819/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eIntroduction:\u003c/h2\u003e \u003cp\u003eDietary supplements are widely used in the United States but remain lightly regulated, raising concerns about contaminants and inconsistent potency. Independent, third-party testing offers a way to assure quality and safety, yet little is known about public interest in such testing. This study examined trends in U.S. interest in third-party tested supplements before and after the Covid-19 pandemic.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eGoogle Trends data from January 2018 to August 2025 were analyzed for terms related to third-party testing (\u0026ldquo;third party tested,\u0026rdquo; \u0026ldquo;USP verified,\u0026rdquo; \u0026ldquo;NSF certified\u0026rdquo;) and for common non-third party supplements (\u0026ldquo;vitamin D,\u0026rdquo; \u0026ldquo;multivitamins,\u0026rdquo; \u0026ldquo;fish oil\u0026rdquo;). Relative search volume was normalized to February 2019. Growth trajectories were compared using Welch\u0026rsquo;s t-tests, Mann\u0026ndash;Whitney U tests, and ordinary least squares regression with time-by-group interaction terms.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eInterest in third-party tested supplements rose sharply beginning in 2021, reaching nearly 800% growth by 2025 compared with \u0026lt;\u0026thinsp;100% growth for non-third party terms. Regression analysis revealed a significantly steeper growth trajectory for third-party terms (β\u0026thinsp;=\u0026thinsp;0.0089, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001; R\u0026sup2; = 0.888). At the individual term level, \u0026ldquo;third party tested\u0026rdquo; exhibited the greatest increase (\u0026gt;\u0026thinsp;1,500%), while \u0026ldquo;NSF certified\u0026rdquo; and \u0026ldquo;USP verified\u0026rdquo; showed more modest but consistent growth.\u003c/p\u003e\u003ch2\u003eDiscussion/Conclusion:\u003c/h2\u003e \u003cp\u003ePublic interest in third-party tested supplements has accelerated beyond general supplement interest since the Covid-19 pandemic, reflecting rising consumer concern with safety and quality. These findings highlight an emerging shift in consumer priorities with implications for public health messaging, regulatory policy, and industry practices. Future research should examine whether increased interest translates into purchasing behavior and evolving regulatory frameworks.\u003c/p\u003e","manuscriptTitle":"Public Interest in Third-Party Tested Dietary Supplements Before and After the Covid-19 Pandemic","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-05 05:54:30","doi":"10.21203/rs.3.rs-8286819/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"2966789e-1bf4-4b9e-8cb3-1f0c4fefe995","owner":[],"postedDate":"January 5th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-02-18T08:26:10+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-05 05:54:30","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8286819","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8286819","identity":"rs-8286819","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}