A cross-sectional study of fatty acids and brain-derived neurotrophic factor (BDNF) in human milk from lactating women following vegan, vegetarian, and omnivore diets

Cross-sectional, observational study of 74 lactating women in the United States; diet patterns vegan (n=26), vegetarian (n=22), omnivore (n=26); inclusion criteria: age ≥18, ≥2 weeks postpartum, healthy, term birth; one breast milk sample collected per participant; fatty acids and BDNF measured.

DHA/EPA supplements; dosage and duration not reported; administration method not specified.

Vegan breast milk had higher unsaturated fat (median 66.0% vs 56.2%) and higher total omega-3 content (2.29% vs 1.46%) compared with vegetarians and omnivores (p<0.001 for both). DHA percentages did not differ by diet; DHA was below 0.30% of total fatty acids in >80% of samples. DHA/EPA supplements were used by 10/74 participants and were more common among vegans; supplement use was a positive predictor of milk ALA, DHA, and total omega-3, and a negative predictor of omega-6:omega-3 ratios. BDNF was not detectable in any samples. Implications: increasing DHA intake via supplementation may help raise milk DHA and overall omega-3 content, particularly where seafood intake is low; milk DHA remained low across diet patterns. BDNF findings are inconclusive and require further study.

Convenience online recruitment with limited ethnic/educational diversity; cross-sectional design with a single milk sample per subject; small sample size (n=74) with potential underpowering for some fatty acids; extended storage times before analysis (average 197 days, 93–257 days before fatty acid/BDNF analysis; average 340 days before creamatocrit); differences in BMI and stage of lactation across diet groups; dietary intake assessed by self-report; no infant outcome data; cannot infer causality between diet/supplement use and milk composition.