The milk of vegetarian mothers is lower in environmental contaminants than the milk of non-vegetarian mothers. Environmental contaminants are stored mainly in fat. Vegetarian diets tend to be lower in fat than those containing animal products, so there is less transfer into human milk.
Even though one study showed vegetarian mothers tend to consume less calcium than other mothers, levels of calcium in human milk were not affected. This is believed to be caused by the fact that vegetarians consume less protein and therefore need less calcium.
Source: La Leche League International
New EnglandJournal of Medicine, March 26, 1981, p. 792
Being a strict vegetarian is beneficial from cradle to grave. Twenty-four breast-feeding mothers were studied, twelve who were strict vegetarians (using no animal products in their diet), and twelve on a conventionalUnited Statesdiet. The strict vegetarian diet was from legumes, grains, fruits, and vegetables. Samples of breast milk were studied from each of the twenty-four women. The samples were analyzed for seventeen different chemical substances. Similar lipid levels were found in the twenty-four samples, an average of 4.23%, with a range of lipids from 1.23% to 7.40%. Most dramatic were the findings in contaminant levels. For every contaminant except polychlorinated biphenyls, in which there was no strong difference between the two groups, there was not even an overlap of ranges, the highest vegetarian value always being lower than the lowest value obtained in the control group.