BACKGROUND: The nutritional profile of human milk varies significantly between women, and the impact of maternal diet on these variations is not well understood. OBJECTIVE: We analyzed breast-milk vitamin B-12 concentration and vitamin B-12 supplement use pattern among women who adhered to different dietary patterns: vegan, vegetarian, and nonvegetarian. DESIGN: A total of 74 milk samples, 29 from vegan, 19 from vegetarian, and 26 from nonvegetarian breastfeeding mothers, were analyzed.

The purpose of the current study was to determine whether there were differences in the fatty acid composition of milk from vegetarian mothers compared to nonvegetarian mothers and whether fatty acid composition was related to length of time on a vegetarian diet. Median time on a vegetarian diet was 81 months (range 36-132 months). Milk fat and fatty acids produced de novo in the mammary gland did not differ between diet groups. Milk from vegetarian women (n = 12) contained higher percentages of the precursors of arachidonic acid compared to nonvegetarian women (n = 7).

The literature review concerning selected nutritional and health aspects of applying different vegetarian diets by breastfeeding women was presented. The only two types of vegetarian diets: lactoovo- and semi-vegetarian, when properly composed, seem to be relatively safe for mother and her child. The most threatening vegetarian diets for lactating women are those including exclusively products of plant origin (so called restricted diets: vegan or macrobiotic).