Vitamins are essential nutrients. Your body needs them in small amounts to stay healthy. Vitamin D regulates the amount of calcium in the body. You need it to make your bones and teeth strong. Without enough vitamin D, our bones can become thin, weak, or misshapen. Vitamin D is also essential for growing infants.

Vitamin D is found naturally in very few foods (fatty fish and egg yolks). The best source of vitamin D is sunlight. The exact amount of sunlight people need to make enough vitamin D depends on their skin color, the time of day they are outside, and the time of the year.

When ultraviolet rays from the sun hit the skin, it triggers your body to synthesize vitamin D. Once in your body, vitamin D needs to be activated through a process known as hydroxylation.

People who live in parts of North America don’t get a lot of sun during the winter months. For that reason, it can be hard to get enough vitamin D. Many Americans are also choosing to avoid the sun or to use sunscreen in order to prevent skin cancer. For this reason, vitamin D is often added to certain foods we eat or drink, like milk. This is through a process called fortification. But even with fortified foods, many people still don’t get enough vitamin D.

Why Does Your Baby Need Vitamin D?

Vitamin D has many roles in the body. Infants and children are growing rapidly. Their bones need a lot of vitamins and minerals to support this growth. In addition to keeping their bones healthy and strong, vitamin D also helps with their immune system, heart, brain, and other organs.

A vitamin D deficiency has also been linked to the following problems:

  • autoimmune diseases like type 1 diabetes, multiple sclerosis, and rheumatoid arthritis
  • osteoporosis
  • heart disease
  • mood disorders
  • certain types of cancer
  • chronic inflammation
  • arthritis

Breastfed babies who don’t receive vitamin D supplements are at an increased risk of developing a condition known as rickets. In rickets, the bones fail to mineralize. This leads to soft bones and skeletal deformities like bowed legs, thick wrists and ankles, and a projected breastbone.

If not treated, rickets can also lead to many complications, including:

  • seizures
  • growth failure
  • short stature
  • lethargy
  • predisposition to respiratory infections
  • curved spine
  • dental problems
  • skeletal deformities

The bone deformities of rickets can usually be fixed if the child is given vitamin D as soon as possible. Some infants may need to have surgery to correct the bone deformities.

Beginning in the 1930s, people in the United States began fortifying their dairy milk with vitamin D. This change has made rickets a rare disease, but the condition is still seen in a few cases a year. Rickets is still a major public health concern in many developing countries.

What Leads to a Deficiency in Vitamin D?

A deficiency of vitamin D is usually caused by not getting enough sunlight. Pregnant or nursing mothers don’t usually get enough vitamin D to provide for both themselves and their babies. The following factors can lead to a deficiency in vitamin D:

  • living in northern latitudes with less sunlight
  • having a condition that affects the way the body absorbs vitamin D, like Celiac disease, cystic fibrosis, or inflammatory bowel disease
  • having dark skin because dark skin doesn’t react as strongly to sunlight; people with dark skin often need five to 10 times more sunlight exposure to generate similar amounts of vitamin D as light-skinned people
  • wearing protective clothing when out in the sun
  • using sunscreen
  • living in an area with high levels of air pollution or dense cloud cover
  • following a vegan or vegetarian diet that doesn’t include fish, eggs, or milk

While getting more sunlight can be beneficial for vitamin D, many people today are avoiding too much sunlight exposure due to the increased risk of skin cancer.

Skin cancer (melanoma) is the most common cancer in the United States. It can be fatal. Most cases are caused by exposure to ultraviolet (UV) light from the sun. High exposure to sunlight also leads to skin aging. Additionally, many people are choosing to stay indoors more often to watch television or surf the Internet.

Since many new mothers are also not getting enough vitamin D for these reasons, babies who are exclusively breastfed are at a higher risk of vitamin D deficiency. That’s because breast milk contains very little vitamin D.

Dark-skinned babies are at a higher risk of developing vitamin D deficiency or rickets. That’s because dark-skinned mothers are also more commonly deficient in vitamin D. A majority of rickets cases occur in breastfed African-American babies.

While the sun is the best source of vitamin D, you should keep your baby out of direct sunlight and have them wear protective clothing to avoid sunburns. For this reason, your baby will need another source of vitamin D in order to keep them healthy.

How Much Vitamin D Should I Give My Baby?

Your baby should be getting 400 IU/day of vitamin D, beginning in the first few days of life.

Breast milk only contains about 25 IU per liter or less, so a supplement of 400 IU per day of oral vitamin D drops is recommended for all breastfed infants. This also includes babies who are partially breastfed (given infant formula some of the time). The vitamin D drops are available over the counter. You can ask your pediatrician for a recommended brand. Be sure to read the label to find out how many drops of the product to give your infant.

If you decide to later wean your baby to only vitamin D-fortified infant formula (at least 1 liter per day), then additional supplements aren’t necessary. All formulas sold in the United States have at least 400 IU/L of vitamin D.

Once you wean your child off of formula, encourage them to drink vitamin D-fortified milk.

The Takeaway

Human milk is still considered the best source of nutrients for your baby in their first year of life. If possible, infants should only drink breast milk for the first 6 months of life.

If you have any concerns regarding the safety of vitamin D supplements for your baby, be sure to contact your doctor. If your baby develops bone pain, muscle weakness, or obvious skeletal deformities, seek medical help.