Day-to-Day Fluctuation in Micronutrient Content in Human Milk Relative to Maternal Diet

The impact of daily variations in habitual maternal intake on human milk (HM) composition has been poorly studied. We aimed to investigate the associations between day-to-day fluctuation in the micronutrient concentration in HM and daily maternal diet. To this end, an observational longitudinal study was carried out. A total of 143 lactating women each compiled a five-day weighed dietary record and concomitantly expressed milk for four successive days. Maternal daily intakes of micronutrients and food groups were analyzed. Free thiamine, free riboflavin, nicotinamide, pantothenic acid, pyridoxal, folic acid, cobalamin, ascorbic and dehydroascorbic acids, retinol, alpha- and gamma-tocopherol, cholecalciferol, and calcidiol in HM were determined for each of the four investigated days. A longitudinal data analysis with generalized estimating equation models was performed. For each daily serving of meat, fish, and eggs, total vitamin D3 levels increased by 243.2 pg/mL (p=0.027) and selenium levels increased by 0.16 ppb (p=0.031) in HM. For every 1 mg/day of riboflavin supplementation, free riboflavin levels in HM increased by 28.6 mcg/L (p=0.019). Pyridoxal levels in HM increased by 6.3 mcg/L per 1 mg/day of vitamin B6 supplementation (p=0.001), and by 2 mcg/L per daily fruit ration (p=0.016). In conclusion, observational longitudinal analysis of HM in a sample of lactating women enables the quantification of the impact of diet and habitual supplement intake on day-to-day HM micronutrient variations.