For Vitamin D. Although docs disagree on whether to give it or not, the only vitamin that breastfeeding babies may need is vitamin d. While breastmilk provides excellent nutrition for babies, the amount of vitamin d in breastmilk varies, even if a mother gets plenty from food or takes a supplement herself. Only d is needed; it can be bought as d alone, or as tri-vi-sol (a/c/d) or as poly-vi-sol (many vits).
To avoid deficiency. Over the past century, many diseases have been identified as being caused by specific vitamin deficiencies. Food and drink in america were then fortified with those important vitamins, so now we hardly see people with vitamin-deficiency diseases. Formula is fortified with the needed vitamins. Babies drinking just breastmilk usually need extra vitamin d.
Vitamin d. Breast milk does not have sufficient vitamin d to prevent bone disease.
Vitamin D. Vitamin d doesn't pass through breast milk - it's the only vitamin that doesn't. For babies partially or completely breast-fed, the vitamin d supplement is one of the few ways we can ensure that they're getting the right amount.
Vitamin D . The aap recommends that all babies get supplemental vitamin d3 (400 iu per day). There are studies demonstrating that exclusively breastfed babies get enough vit d from moms if moms take 4000-6000iu d3 per day.