While Dr. Anthony Fauci admits most “so-called immune boosting” supplements being marketing amid Covid-19 mostly do “nothing,” he does believe in the benefits of vitamin D.
“If you are deficient in vitamin D, that does have an impact on your susceptibility to infection. So I would not mind recommending, and I do it myself taking vitamin D supplements,” Fauci, 79, said during an Instagram Live on Sept. 10.
But figuring out if whether you are vitamin D deficient and how much of the supplement you need to take is complicated. In fact, medical professionals have been debating the efficacy of routine vitamin D screenings and supplementation recommendations for years.
“You’re wandering into a maze,” Dr. Clifford Rosen, an endocrinologist and professor of medicine at Tufts University’s School of Medicine, who has studied vitamin D for more than 30 years, tells CNBC Make It.
Here’s what you need to know from three experts.
Why vitamin D is important
Vitamin D is a fat-soluble vitamin that plays an important role building and maintaining muscles and overall bone health. People who have low vitamin D may develop soft, than and brittle bones.
The primary sources of vitamin D is through direct sunlight and it can also be obtained through foods such as fatty fish (salmon, tuna and mackerel), mushrooms and milk.
What’s more, researchers at the University of Chicago Medicine found a link between vitamin D deficiency and the likelihood of being infected with Covid-19 — those with an untreated deficiency were more likely to test positive, according to the study published in September. (The National Institutes of Health released a statement last updated in July saying “there are insufficient data to recommend either for or against the use of vitamin D for the prevention or treatment of Covid-19.”)
How do you know if you are vitamin D deficient?
According to study published in 2014 by the NIH, researchers estimated that 35% of adults and nearly 50% of infants in the U.S. had a vitamin D deficiency.
Without a blood test (more on that later), it can be hard to tell. Early signs of vitamin D deficiency are subtle if they even existent. You may not show any symptoms at all, according to experts.
But vitamin D deficiency can cause accelerated skin aging and dry skin, according to Dr. Raman Madan, a dermatologist at Northwell Health’s Huntington Hospital. And over time, severe deficiency can result in muscle weakness and bone fractures, says Paul Thomas, a registered dietitian nutritionist and scientific consultant at the National Institutes of Health’s Office of Dietary Supplement.
Studies have also found that prolonged vitamin D deficiency can cause bone-related diseases in adults and children.
All that said, the only way to truly know if you are vitamin D deficient is to get a blood test through your doctor, says Thomas.
Not all medical professionals, however, think routine testing for vitamin D is a good idea.