Real Possibilities

October 12-18, 2020

Vitamin D and COVID-19


By Nan Selz
Executive Council, AARP Arkansas


There’s been a lot of false and misleading information about COVID-19 lately and some of it involves vitamin D. Researchers are still investigating whether a deficiency in vitamin D impacts the severity of this viral infection. Even if it’s not beneficial in preventing or treating COVID-19, vitamin D is essential to good health. 


Vitamin D plays a significant role in the absorption of calcium, a nutrient which strengthens bones and muscles. Vitamin D deficiency has been linked to type 2 diabetes, cardiovascular health and breast cancer. But doctors are not sure if this linkage represents conditions that are the result of a vitamin D deficiency or if the deficiency itself is a result of poor health. 


A recent study estimated that 40 percent of Americans are deficient in vitamin D. Possible causes of this condition could include any of the following situations:

• Since skin absorbs ultraviolet-B (UVB) rays to manufacture the nutrient, infrequent exposure to the sun can lead to an insufficiency of vitamin D. People who live where winters are long often experience lowered levels. Fortunately, sunscreen does not prevent the formation of vitamin D, although clothing does.

• The extra melanin in dark skin can interfere with the skin’s ability to absorb vitamin D from the sun; therefore, people with dark skin may need to have their levels monitored.

• Starting at age 50, people begin to lose some ability to synthesize vitamin D from both sunlight and from food so they frequently exhibit low levels.

• People who are overweight often have a vitamin D deficiency. One study showed that for every 10 percent increase in BMI (body mass index) there is a 4.2 percent drop in levels of vitamin D.

• Diseases of the gastrointestinal system can prevent the intestines from absorbing vitamin D as can certain medications such as steroids.


The importance of sufficient levels of Vitamin D cannot be overstated. There is some evidence that appropriate levels of Vitamin D may benefit both cancer prevention and outcomes in cancer treatment. As stated above, Vitamin D and calcium are essential in maintaining strong bones throughout life. Research conducted in 2017 involving 11,000 participants found evidence that Vitamin D may play a role in protecting against upper respiratory tract infections, but no clear connection with COVID-19 has been found.


There are warnings, however, against taking excessive doses of this vitamin since very high intakes can have serious side-effects including kidney disease. “If your vitamin D level is sufficient, it doesn’t seem like you get a lot of benefit from supplementation,” says Karl Nadolsky, a clinical endocrinologist at Michigan State University.


The message on Vitamin D is loud and clear. Everyone should maintain sufficient levels of this important nutrient for good health; but overdosing on supplements is risky. And, for now, there is no reason to assume it will help prevent or treat COVID-19.


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  • Nan Selz
    Nan Selz