A: Congratulations, Trisha, for giving your baby such a great start with your breast milk! You are correct that breast milk contains all the nutrients your baby needs, but we have recently discovered an increase in vitamin D deficiency among breastfed babies, which can cause a condition called rickets. Originally thought to affect darker-skin infants who were not exposed to sunlight, we have increasingly seen rickets in light-skin babies as well and believe that this is due to the higher SPF sunscreens formulated for babies.

While we get some vitamin D from our foods, we metabolize 90 percent of our required needs through sunlight exposure. Sunscreen blocks the ultraviolet rays of the sun required to activate the chemicals in the skin that make the vitamin. The risks of excessive sun exposure are well documented, and sunscreens are routinely recommended for all children. Additionally, we have a growing tendency to keep our babies inside, or well covered when they are outside, and because you live in a cold weather climate for at least half of the year, you probably go from your house to your car to your destination during the winter months. Prescoting vitamin D for all breastfed babies is probably a wise thing to do, at least until some better guidelines are developed regarding infants and sun exposure. Additional supplementation is not necessary for formula-fed babies because the vitamin is already added to the milk.