Milk proteins in breast milk break down into peptides that have opiate like drug effects; this helps bond child to mother, but can cause a problem if people continue to drink milk into adulthood. Babies three months and under should ideally be fed only breast milk. Human breast milk is the only animal product that is high in antioxidants. And the breast milk of vegetarians may only have 1-2% of PCBs, DDTs, and dioxins, but vegans who do not supplement or fortify their diets with Vitamin B12 will have deficient breast milk and place their child in danger (see also here, here). They must also be careful about getting enough iodine.
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