Formula-fed infants generally don’t need supplements until they are about 6 months old and start taking more solids and less formula. At that point a liquid or powdered multivitamin is a good idea to help fill in the gaps in the diet. Make sure your baby’s formula contains DHA to help brain development. Formula should be made with filtered tap water so baby gets fluoride for healthy teeth. Make sure your filter removes lead and volatile organic compounds like pesticides. These are often found in tap water and are NOT good for development. Filtering is much less expensive than buying bottled water and keeps all those empty bottles out of the landfills.
Breastfed babies depend on mom’s diet for their nutrition. Breastfeeding moms should be sure to take a multivitamin with iron and a fish oil supplement with DHA (check the women-before-menopause page). After six months a breastfed infant should take vitamin D for sure and also can use a liquid or powdered multivitamin to fill in gaps in the diet.
You also should consider what products you put on your baby’s outside. Tear-free shampoos aren’t less caustic than others, they just have an anesthetic in them so baby doesn’t feel the irritation of soap in the eyes. Instead why not choose something naturally gentle? Also check and make sure botanicals in your baby’s soap and lotion are organic to avoid pesticides.