Routine use of vitamins and supplements are generally not necessary for lactating women unless they have nutritional deficiencies or are on caloric restriction.  Lactating women are encouraged to consume a diet rich in fruits, vegetables, whole grains, dairy and protein. For some women, a daily prenatal vitamin may be recommended or Vitamin B12 supplements may be necessary for women who do not consume animal products and calcium supplements may be necessary in a diet without adequate calcium intake.  These supplements are for mother's benefit – and not for baby's. 

Vitamins that dissolve in water, such as Vitamin B, Vitamin C and minerals such as iron, calcium, copper and zinc do not accumulate in breast milk and are considered safe.  Vitamins that dissolve in fat, such as Vitamins A and E, can accumulate in the mother's milk and cause harm to breastfed babies if taken in excessive amounts.  It is encouraged to discuss the need for additional vitamin supplementation with your physician as the recommendations may change on a case by case basis. 

In addition to vitamins, there are also special considerations when taking herbal supplements. Many herbal preparations lack the rules and regulations as well as the quality control mechanisms needed to determine the safety of the ingredients and dosing regimens.  Some general guidelines include avoiding unlabelled supplements and supplements that combine several active ingredients.  Although some herbs and herbal teas are considered safe for breastfeeding women, nursing mothers should have a discussion with their physician prior to consumption.