Vitamin D and Babies: What You Need to Know

Written Dr. Seran Kim, board-certified Emergency Physician

Vitamin D is needed to support healthy bone development. But do babies really need vitamin D?

The short answer is yes.

What is vitamin D deficiency?

Currently, fewer than 40% of infants under 1 year of age in the U.S. are meeting the American Academy of Pediatrics vitamin D intake requirements. In growing children, vitamin D deficiency can result in a medical condition called rickets (soft and weak bones). This can lead to bone deformity and scoliosis and may be associated with fractures. Other health complications include bone pain, muscle weakness, seizures, tetany, heart arrhythmias, dental abnormalities, stunted growth and developmental delay.

Signs and symptoms of vitamin D deficiency

It is often difficult to diagnose vitamin D deficiency, as the symptoms are very vague, and by the time signs start to appear, the deficiency is quite pronounced. Signs of severe vitamin D deficiency include:

• Pain or tenderness in the bones of the arms, legs, pelvis, or spine
• Stunted growth and short stature
• Delayed motor skills
• Bone fractures
• Muscle weakness
• Teeth deformities, such as delayed tooth formation, holes in the enamel, abscesses, defects in the tooth structure and an increased number of cavities
• Skeletal deformities, including irregularly shaped skull, bowlegs or knock knees, bumps in the ribcage, a protruding breastbone, a curved spine, pelvic deformities and thickened wrists and ankles

What are sources of Vitamin D?

Thankfully, many foods are fortified with Vitamin D in the United States. These include cereals, bread, milk, orange juice, and yogurt. However, newborn babies and infants are most at risk of vitamin D deficiency because they do not yet consume solid foods.

Vitamin D is also synthesized by the skin through ultraviolet light exposure. Multiple factors affect how much of the UV rays actually reach the skin, including latitude, time of day, season, cloudiness and air pollution. Due to this unpredictability, as well as the increased risk of skin cancer with UV exposure, consumption of vitamin D through diet and supplementation is the most dependable way to ensure adequate intake.

What is Vitamin D supplementation for babies?

All infants (whether breast-fed or formula-fed) should have a minimum of 400 International Units (IU) of vitamin D per day, beginning in the first few days of life. Even though it has many beneficial nutrients, breast milk alone does not provide infants with an adequate amount of vitamin D (even if mothers are taking vitamins containing vitamin D).

The AAP recommends the following general guidelines:

• You can start supplementation within a few days of birth.
• For breastfed and partially breastfed babies, administer 400 IU of vitamin D per day. Continue supplementation until your baby is older than 1 year of age and drinks 1 liter (32 oz) of whole cow’s milk per day.
• For formula-fed babies, supplement with 400 IU of vitamin D per day, until your baby starts to drink 1 liter (32 oz) of formula per day. All formulas sold in the U.S. are fortified with vitamin D, but be sure to double-check the vitamin D content per serving, as not all formulas are the same. Continue supplementation until your baby receives 400 IU per day, or they are older than 1 year of age and drink 1 liter (32 oz) of whole cow’s milk per day.

It is important to note that cow’s milk should not be given to babies younger than 12 months of age, due to an inability of young infants to properly digest cow milk proteins. They are also at increased risk for diabetes, iron deficiency and milk allergy if exposed to cow’s milk too early. Be sure to discuss any questions or concerns with your pediatrician.

What are vitamin D drops?

Vitamin D is measured in International Units (IU). Be sure to select a brand of drops that is formulated specifically for babies, and does not contain any artificial colors, flavors or preservatives. Also try to find a brand that has a concentrate of 400 IU per drop dosage. Keep the drops in their original package, so that you or other caregivers can easily follow the directions. Always use the dropper that comes with the product, as it is manufactured specifically for that specific brand of vitamin D supplement drops.

Can you give a baby too much vitamin D?

Excess vitamin D can actually lead to extremely high blood calcium levels, which can then cause nausea and vomiting, loss of appetite, excessive thirst, frequent urination, constipation, abdominal pain, muscle weakness/pain, confusion, fatigue and even kidney damage.

When giving your baby vitamin D, make sure you do not exceed more than the recommended amount.

Say yes to D!

Vitamin D supplementation is an important step in ensuring good bone health for your growing baby. Remember that rickets is avoidable, and prevention is key. Babies need 400 IU of vitamin D per day, whether they are breastfed or formula-fed (or any combination in between).

Start supplementation within a few days of birth, and continue until your baby is able to receive 400 IU from cow’s milk or drinks enough formula with more than 400 IU daily.

Once your baby is older, you can start to add naturally vitamin D-rich foods into their diet, such as salmon, egg yolks and mushrooms. Be sure to check in with your pediatrician along the way.

Factually reviewed by Dr. Seran Kim, board-certified Emergency Physician, on June 9, 2021.