Discussion
milk folate, neurological disorders, human milk and blood collections, human milk folate, allergic diseases
NEUROLOGICAL DISORDERS
This investigation provides evidence that the human milk folate profile can be altered by maternal folate supplementation; at a dose of 0.6 mg/day, folic acid resulted in significantly higher UMFA in human milk as compared to (6The effect of folic acid supplementation on human milk UMFA was fairly congruent with previous evidence, and further supports that the impact of maternal folic acid supplementation on the human milk folate profile is dose-dependent. In the current study, UMFA represented ~ 28% of total milk folate following supplementation with 0.6 mg/day folic acid; in other reported studies, UMFA represented ~ 8% of total milk folate following a lower dose (0.4 mg/day)Conversely, milk UMFA following (6Previous evidence suggests that UMFA may be incorporated into human milk at the expense of 5-MTHFIt has been hypothesized that UMFA in human milk could negatively impact infant folate statusUltimately, the biological and clinical consequences of the capacity to absorb protein-bound folate and subsequent influx of UMFA into infant circulation remains unclear. Current human studies are mainly limited to observational designs and have produced mixed results for outcomes including neurological disorders and allergic diseases, and generally fail to demonstrate an association with UMFA specificallyStrengths of this investigation include the rigorous methods for milk collection, adherence to the study protocol and daily supplementation, and quantification methods which captured total milk folate including 5-MTHF degradation product, MeFox. The association between UMFA in maternal plasma and human milk is limited by sample collection on separate days; however, it is unlikely that this substantially biased results, as human milk and blood collections occurred within ≤ 4 days for almost all participants, with standardized folate supplementation prior to collection. It is possible that the difference in milk UMFA between groups would have been less apparent if folate supplementation had not occurred 2 h prior to the milk collection; however, our findings represent the impact of folic acid consumption (via supplements or possibly fortified foods) on the human milk folate profile when maternal plasma UMFA may be at its peak. Finally, human milk folate concentrations increase with advancing lactation, with lowest concentrations in colostrum, peaking at 2–3 months postpartumIn conclusion, as human milk may serve as the sole source of infant nutrition, it is imperative to understand factors which impact its composition. While others have shown that supplemental folic acid at recommended doses (0.4 mg/day) did not increase concentrations of human milk UMFA as compared to (6