Expert answer: Bridget Swinney, nutritionist

In most cases, breast milk or formula provides just about everything a baby needs for the first four to six months. The exception is vitamin D, which is recommended as a supplement for breastfed babies and babies who drink less than 32 ounces of formula per day.

The American Academy of Pediatrics (AAP) now recommends that you give your breastfed baby a supplement of 400 IU per day of vitamin D, starting in the first few days of life. Babies who are fully or partially formula fed but drink less than 32 ounces of formula a day also need a daily 400 IU vitamin D supplement.

After age 4 to 6 months, as your baby's diet gradually changes from an all-liquid diet to one that contains more and more solid food, your doctor may or may not recommend additional vitamin supplements.

Babies who eat a variety of foods over time shouldn't need them, but there are exceptions. For example, supplements may be necessary if your baby was born prematurely, at a low birth weight, or small for gestational age; consistently drinks less breast milk or formula than other babies his or her age and doesn't make up the difference with food: or has chronic health problems that affect his or her ability to eat. Be sure to ask your baby's healthcare provider if you have special concerns.

Your own health picture may come into play too. For example, women who have had gastric bypass surgery or who take certain medications daily may absorb fewer nutrients. This can reduce the nutrient content of their breast milk.

If you follow a vegan diet, tell your baby's healthcare provider. Vitamin B12, iron, zinc, calcium, and omega-3 fatty acids are nutrients that vegan moms and babies may need to make an extra effort to consume through diet or a multivitamin-mineral supplement.

In general, though, even if your diet isn't perfect (and whose is?), your breast milk will likely contain the nutrients your baby needs. That said, your own nutrient stores may suffer if your diet is less than stellar, so consider taking a multivitamin while you're breastfeeding. You may also want to take a DHA supplement. DHA is an omega-3 fatty acid that's important for infant brain and eye development, and also benefits new moms.

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