Vitamin D helps to ensure that our bodies absorb and retain calcium and phosphorous, which are both needed for building strong bones. It also plays a part in heart health and fighting infection. The need for vitamin D begins even before a baby is born.

Why is vitamin D so important?

Kids need vitamin D to build strong bones. It also helps bones heal after an injury or surgery. Severe vitamin D deficiency can lead to nutritional rickets, which causes softened and weakened bones. This disease is most often seen in children younger than 2 years of age. The American Academy of Pediatrics (AAP) now recommends that all infants have a minimum intake of 400 International Units (IU) of vitamin D per day beginning soon after birth.

Vitamin D can be obtained in two ways: from the foods we eat and made in the skin after exposure to ultraviolet (UV) light.

Vitamin D from the sun

Our bodies make vitamin D when our skin is exposed to the sun, but it’s difficult for newborns to get enough that way. Short periods of sun exposure are sometimes recommended to obtain vitamin D, but sun exposure must be handled safely. The AAP recommends that children six months of age and younger be kept out of the sun altogether and infants six months and older should wear protective clothing and sunscreen to minimize their exposure to sunlight. Because of this, infants need to get the majority of the vitamin D they need from their diets.

Vitamin D from food

According to the AAP, the primary source of nutrition for infants should be breastmilk or infant formula. Because breastmilk does not contain enough vitamin D, breastfed or partially breastfed infants should be supplemented with 400 IU of vitamin D per day beginning in the first few days of life. If a baby is on an infant formula, they still may need a vitamin D supplement.  All infant formulas are made to provide 400 IU of vitamin D in 32 ounces (about 1 liter). But if an infant is drinking less than 32 ounces of formula each day, then a vitamin D supplement is needed.

Liquid supplements are the best option for infants. Some preparations provide the recommended amount of 400 IU in ½ mL, 1 mL, or a one-drop dose. Supplementation should continue until a baby is weaned to at least 24 ounces of vitamin D-fortified whole milk per day. It’s important to remember, though, that whole milk should not be started until an infant is 12 months of age. When solid foods are introduced, babies can also get vitamin D from foods like oily fish (such as salmon), egg yolks, and fortified foods like yogurt, cheese, and ready-to-eat cereals. 

If you’re unsure if your baby is getting enough vitamin D from food, your pediatrician can determine if they need have their vitamin D levels checked.

Pregnant people need vitamin D, too!

During pregnancy it is important to get enough vitamin D, since the pregnant person’s intake directly affects their baby’s vitamin D levels at birth and during the first 2-3 months of life. There may also be some bone-density loss during pregnancy, so a vitamin D and calcium supplement can help reduce those effects. Expectant parents should speak with their obstetricians to have their vitamin D levels checked.