Vitamin D Supplements: What Parents Should Know

Getting enough vitamin D is essential so kids’ bones can grow strong and their immune systems can ward off illness.

Vitamin D gets into the body through absorption of sunlight and ingestion of food. From April through the end of October, spending just 15 to 30 minutes outside in the middle of the day with hands and face exposed will stimulate the skin to make all the vitamin D your child needs. In fact, on a sunny summer day, a child wearing a bathing suit can generate 10,000 to 20,000 international units (IU) of vitamin D after 15 to 30 minutes. In a neat biological trick, a person’s body can’t “overdose” on vitamin D created by the sun.

Foods such as salmon, sardines, tuna, cod liver oil, egg yolks and shiitake mushrooms contain a lot of vitamin D. Many kids don’t seem to love these vitamin D superfoods, so luckily store-bought milk is often fortified with vitamin D, as are many cereals and even orange juice. Not all dairy products are fortified with vitamin D, however, so make sure to read the labels.

When vitamin D supplements are helpful

During the fall and winter, when the sun’s rays aren’t at an angle that will produce vitamin D in the skin, it’s good to give your child a vitamin. Most over-the-counter children’s vitamins contain 600 IU of vitamin D, which is the recommended daily allowance set by the U.S. Food and Drug Administration for kids 1 year old and older.

Children who are obese, who have dark skin, who rarely go outside or who wear clothing that covers most of their skin may need supplements to ensure they have adequate levels of vitamin D all year round. Some medications, such as anticonvulsants, as well as over-the-counter health aids like St. John’s Wort, can  interfere with the way our bodies metabolize vitamin D. Certain conditions, such as celiac disease, can also interfere with absorption of vitamin D. Discuss your child’s medical history and lifestyle with your pediatrician, and make sure to them about any medicine or herbal supplements your child takes. Your pediatrician can then determine your child’s daily vitamin D requirement.

There are risks if kids take in too much vitamin D from supplements and food, including an increased chance of developing kidney stones. Parents need to calculate the amount of vitamin D their child gets from fortified milk, other food, and vitamin supplements to make sure the total amount does not exceed:

• 1,000 to 1,500 IU a day for infants
• 2,500 to 3,000 IU a day for children 1 to 8 years old
• 4,000 IU a day for children 9 years and older

The sunscreen paradox

Parents know that it’s important to protect their child’s skin from dangerous sunburns, skin damage and future skin cancers by using sunscreen. But sunscreen can reduce vitamin D production by 95% (SPF 8) to 99% (SPF 15).

What’s a parent to do?

“In reality, this is not much of a problem from the perspective of vitamin D,” says Michael A. Levine, MD, Director of the Center for Bone Health at Children’s Hospital of Philadelphia (CHOP). “We usually recommend that parents allow children to have 10 to 15 minutes of sun time before applying sunscreen. This allows them to have sufficient exposure to sunlight to meet their vitamin D requirements. Even after application of sunscreen, kids continue to make some vitamin D, as most kids — and adults, too — don’t actually apply adequate amounts of sunscreen before going out into the sun. And many forget to reapply sunscreen as directed after several hours or after going into water. So, in most cases, sunscreen use really does not interfere with getting enough vitamin D.”

Babies need a vitamin D boost

Because a typical mother’s breast milk does not give her baby enough vitamin D, breastfed babies need vitamin D supplementation. Either the baby can be given drops of 400 IU a day directly or the mother can take 5,000 IU a day (half the safety threshold), which will fortify her milk with enough vitamin D for the baby. We call this “super milk”!

Although all standard infant formulas are fortified with vitamin D, vitamin D supplementation is also recommended for formula-fed babies. “A baby would need to drink a quart of formula each day to get the recommended amount of vitamin D,” Dr. Levine says, “and young infants may not take in that much.” Consult with your baby’s pediatrician or healthcare provider to make sure they are getting all the vitamin D they need.

Vitamin D testing

Vitamin D status can be easily determined by a simple blood test that measures the major circulating form of vitamin D, called 25-hydroxyvitamin D or 25(OH)D. Routine testing isn’t recommended for all children, but some may benefit from a laboratory assessment.

Although some labs report levels below 30 ng/mL (nanograms per milliliter) as low, most pediatric bone specialists agree that levels greater than 20 ng/mL of 25(OH)D are adequate for most children.

Long-term benefits of adequate vitamin D

There have been hints vitamin D may actually help prevent some diseases. Nearly all of these studies have been performed in adults, so the results may not be generalizable to children. For the most part, studies that identify associations between disease risk and low levels of vitamin D have not been confirmed by well-designed clinical trials. In some cases, a lack of benefit has been attributed to the inclusion of patients who already had high levels of vitamin D. In other instances, a lack of benefit has been blamed on the use of vitamin D doses that were too low.

Several studies have failed to demonstrate a relationship between vitamin D status and the risk of developing type 1 diabetes, the form of diabetes that is most common in children. In addition, the idea that vitamin D supplements may prevent type 2 diabetes, the form of diabetes common in older children and adults, was recently dealt a blow in a rigorous study of adults. In June 2019, a National Institutes of Health-funded study of 2,423 adults reported that daily vitamin D supplements failed to prevent type 2 diabetes. By contrast, a more recent study published in 2020 examined the collective effect of nine randomized clinical trials that tested the ability of vitamin D supplements to prevent progression from prediabetes to type 2 diabetes. Overall, there was no benefit, but when only the trials that used moderate to high doses of supplementation (≥1000 IU/day) were assessed, there was a small 12% reduction of risk compared to placebo.

“These studies should be interpreted cautiously, not the least because they did not include children. Overall, it’s doubtful that high-risk kids — those with a sibling with type 1 diabetes or a parent with type 2 diabetes — would have their risk of diabetes reduced by taking vitamin D supplements,” says Dr. Levine.

Strong bones continue to be the most significant benefit of vitamin D. However, the vitamin is also known to support nervous system health, strengthen defenses against infections and may also improve lung and heart health.