Vitamin A, D, E and K intakes, status, and breastmilk concentrations in breastfeeding women in Ireland.

BACKGROUND: Fat-soluble vitamins A, D, E and K are critical during the postpartum period for maternal recovery and infant development. OBJECTIVE: To determine the concentrations of vitamins A, D, E and K in maternal serum and breastmilk during the early postpartum period in breastfeeding women. METHODS: This was a secondary analysis of the WellFed 4-week randomized controlled trial (RCT). Dietary recalls, serum, and breastmilk samples were collected from breastfeeding women at 4 and 8 weeks postpartum (n=48). Vitamin status and metabolic biomarkers were quantified using LC-MS/MS and a clinical analyzer, respectively. Associations were analyzed using correlation, regression, and mediation analysis (PROCESS macro for SPSS). RESULTS: were below the analytical detection limit. Serum and breastmilk α-tocopherol were correlated (r=0.363, p=0.013, adjusted p=0.026). Total cholesterol, triglycerides and CRP predicted up to 56% of serum α-tocopherol variance. CONCLUSIONS: Maternal serum concentrations of vitamins A, E and K were adequate, while approximately two-thirds of women were vitamin D sufficient. Breastmilk vitamins A and E were adequate and higher than previously reported, whereas vitamin D metabolites were undetectable. Dietary intake was positively associated with serum vitamins A and D, while serum vitamin E was associated with lipid-related biomarkers and correlated with breastmilk α-tocopherol, highlighting a potential link between maternal metabolic health and vitamin E in breastmilk. CLINICAL TRIALS REGISTRY: The WellFed RCT was registered at https://clinicaltrials.gov/study/NCT05924633 as NCT0592463.