Winter vitamin D deficiency weakens immune system, increases risk of viral infections

EL PASO, TX, March 12, 2020 /24-7PressRelease/ — Michael F. Holick, MD, PhD, Professor of Physiology and Biophysics, and leading authority on vitamin D, writes:

“Most children and adults are vitamin D deficient in the winter. Essentially no vitamin D can be made from sun exposure during the months of November through March if you live above or below 35 degrees latitude (e.g. Busan, S. Korea, Xi’an, China, Atlanta, USA or Malaga, Spain).

It has been suggested that there is a seasonal stimulus for developing viral infections such as the flu during the winter time. At the time of the peak flu season in the winter is at exactly the same time a person’s vitamin D status [blood level of 25-hydroxyvitamin D] is at its lowest level. Vitamin D plays an important role in maintaining a healthy immune system and therefore winter-associated vitamin D deficiency can weaken the immune system increasing the risk of developing viral infections that cause upper respiratory tract infections. There is evidence that adequate levels of vitamin D during the winter can result in a reduction in the incidence of influenza A and in other viral illnesses of the respiratory tract.

Given the newness of the coronavirus (COVID-19), no research has studied how vitamin D levels might be associated with the incidence or severity of a coronavirus infection. However, at this time I believe it is prudent to make sure everyone has adequate vitamin D levels.”

Ernest T. Armstrong, inventor of the vitamin D promoting sunscreen Solar D® (, writes: “All countries worst hit by COVID-19 are northern, wintertime countries or countries where people get very little sunshine and therefore make very little vitamin D in their skin. If the COVID-19 acts similar to other known seasonal coronaviruses, then in the spring as the sun climbs higher in the sky, people will make more vitamin D, immune-system suppression will lessen, and the number of new cases of COVID-19 will fall dramatically.”

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