Advance with MUSC Health

Vitamin D supplements can protect us against deficiency, MUSC Children's Health doctor says

Advance With MUSC Health
June 23, 2022
Carol Wagner, M.D.
Carol Wagner, M.D. specializes in neonatology at MUSC Shawn Jenkins Children's Hospital.

Vitamin D isn’t really a vitamin at all. But that doesn’t make it any less critical for our health. It’s a steroid and, unlike vitamins, is produced in our bodies when our skin is exposed to UVB sunlight. The sun triggers a chemical reaction that produces calciferol, a form of vitamin D that is carried into the bloodstream to every organ, says Dr. Carol L. Wagner, attending neonatologist at MUSC Shawn Jenkins Children's Hospital and a professor of pediatrics at MUSC.

The fact that we can make our own vitamin D is good news. The reality is that most of us don’t make enough because we don’t get enough sun exposure consistently year-round, even in sunny South Carolina, Dr. Wagner says. And for all its protective benefits, sunscreen prevents our skin from absorbing the UVB light that turns our bodies into vitamin D.

And while a diet of oily fish such as salmon, mackerel and swordfish, egg yolks, mushrooms, fortified milk, and fortified orange juice provides vitamin D, 90 percent of your daily vitamin D comes from sunlight, Dr. Wagner says.

As a result, most people have vitamin D deficiency, particularly those with darker skin pigmentation and who live in Northern regions that get less sunlight during the winter.

“The farther people live from the equator, the more at risk they are for deficiency,” Dr. Wagner says. “Middle Eastern women who must wear clothing that covers their bodies from head to toe have profound deficiencies.”

Vitamin D is essential for good bone health and, over the last 30 years, has been the subject of numerous studies showing it also has immune-boosting properties. In the 1940s, researchers found that children with vitamin D deficiency not only had rickets, but also a lot of respiratory infections. When given doses of cod liver oil, which is high in vitamin D, children developed fewer respiratory infections.

Now vitamin D is getting its due and being recognized for its role in strengthening immunity.

“It’s as if a veil has been lifted, Dr. Wagner says. “Researchers started looking at it in a different light, beyond its effect on calcium and bone health. It was viewed in an unusual way. It’s still controversial, but a plethora of data show its profound effect on deficiency. Research has shown that vitamin D revs up infection-fighting cells, monocytes and macrophages, to achieve immune balance and for our bodies to fight off infections. Vitamin D boosts our ability to fight certain cancers, such as breast, prostate and colon cancer and certain conditions such as multiple sclerosis and rheumatoid arthritis. It doesn’t mean you won’t get these diseases, but your ability to fight and identify foreign cells when deficient in vitamin D puts you at risk because your immune system is at risk.”

How much vitamin D do we need?

Unequivocally, 4,400 international units daily are very safe in adults, says Dr. Wagner, who has conducted research and published on the benefits of vitamin D. Lactating women need more: 6,400 international units. People recovering from illness and who have been hospitalized or inactive and weak should up their daily amount to 10,000 for about a week and then decrease it to 4,000-5000 a day. Newborn babies should have 400 IUs a day in the form of a liquid oral supplement.

“Given how we live in the United States, everyone should take vitamin D,” she says.

Vitamin D comes in 2 forms: D2, ergocalciferol, which comes from plants, and D3, cholecalciferol, which comes from animal sources and is the form we make in our own bodies.

“Vitamin D3 is thought to be more potent because, when it is metabolized, it raises the level of calcifediol, which is the main form of vitamin D in the blood, more than D2 does,” Dr. Wagner says. “Our calcifediol level indicates the amount of vitamin D in our blood.”

A healthy level is 40 to 60 nanograms; the upper limit is 100 nanograms.

Signs of excessive vitamin D are nausea, vomiting, constipation, and feeling ill. Signs of too little vitamin D include muscle and/or bone pain, and overall weakness.

“Whatever way you choose to get vitamin D, be sure to have your level checked annually,” Dr. Wagner says. “That way you can be assured you’re getting the proper amount for maintaining healthy bones and immune balance. It’s essential for good health.”