COVID-19 and Vitamin D: What Does the Research Say?

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Can vitamin D help fight COVID? Science can’t say for certain just yet. However, recent research has found that vitamin D deficiency may be linked to an increased number of COVID-19 cases and deaths.

COVID-19 and Vitamin D: What Does the Research Say?

Results of unpublished research from Northwestern University on the relationship between COVID-19 and vitamin D levels were released in May. It should be noted that the study has not been subjected to the scrutiny of the academic journal peer-review process.

Researchers analyzed patient data from hospitals and clinics in ten countries — China, France, Germany, Italy, Iran, South Korea, Spain, Switzerland, the United Kingdom and the United States. They found that COVID patients with severely low vitamin D levels were twice as likely to experience severe complications and had higher mortality rates. They also found a correlation between vitamin D levels and what’s known as cytokine storm, a hyperinflammatory condition caused by an overactive immune system. A cytokine storm can damage the lungs — and is ultimately the reason for a majority of COVID-19 deaths.

Researchers noted that patients from countries with high COVID-19 mortality rates such as Italy, Spain, and the United Kingdom had lower levels of vitamin D compared to patients from countries with higher vitamin D levels.

While healthcare, age and lack of resources could play a role in these findings, Vadim Backman, lead researcher and Walter Dill Scott professor of biomedical engineering at Northwestern University, said in a university press statement that Italy’s healthcare system is one of the best in the world.

“Differences in mortality exist even if one looks across the same age group. And, while the restrictions on testing do indeed vary, the disparities in mortality still exist even when we looked at countries or populations for which similar testing rates apply. Instead, we saw a significant correlation with vitamin D deficiency,” Backman said.

Susan Lanham-New, head of the Department of Nutritional Sciences at the University of Surrey in the United Kingdom and lead author of a scientific literature review of associations between vitamin D, influenza, upper respiratory tract infections and immune health published in May and updated June 9 in BMJ (formerly the British Medical Journal), emailed with MedTruth.

“If an individual is vitamin D deficient, in children, this will make them at risk of rickets (soft bones) and in adults will put them at risk of osteomalacia (the symptoms of which are bone pain, muscle ache, lethargy, susceptibility to infection),” Lanham-New told MedTruth by email. “Vitamin D is also important to other health outcomes including risk of diabetes, obesity, cardiovascular health, some cancers and the immune system.”

And a third, somewhat older study published in the BMJ in 2017, found that vitamin D can lower the likelihood of getting an acute respiratory tract infection. Coronaviruses are common colds and upper respiratory infections and COVID-19 is the name for the disease of the new coronavirus.

Vitamin D Supplementation

The recommended dose of vitamin D is solely based on your deficiency. Simply put, don’t take vitamin D supplements to prevent COVID-19. For folks who are deficient, Backman says the vitamin should be considered in supplemental form.

“This might be another key to helping protect vulnerable populations, such as African-American and elderly patients, who have a prevalence of vitamin D deficiency,” Backman said on the topic of COVID-19.

MedTruth spoke to Dr. Romy Block, an endocrinologist in Chicago, co-author of “The Vitamin Solution: Two Doctors Clear the Confusion about Vitamins and Your Health” and co-founder of Vous Vitamin. While Block advises basing supplementation on individual needs, many people may be experiencing vitamin D deficiencies without even realizing it. Muscular weakness, bone and joint pain, bone loss, fatigue and depression can all be symptoms of vitamin D deficiency, according to the Cleveland Clinic.

“It seems that the countries with most severe cases of COVID-19 are also those with the most vitamin D deficiency. At this point, this is a correlation but by no means a proof of causation. However, we do know that vitamin D is an important vitamin for immunity and white blood cells do have vitamin D receptors. Vitamin D may also play a role in lowering inflammation and preventing autoimmune illness which may also be in part why it may help prevent severe illness related to COVID-19,” Block said. However, this information is not definitive as there are no concrete findings or study’s securing this data.

Vitamin D is beneficial in many ways like promoting bone growth, cell growth, immune function and the reduction of inflammation. If you’re deficient, which a simple blood test can determine, you may want to consider supplementation. Sunlight exposure and diet may not give you the vitamin D that you need. Talk to your health provider before increasing your vitamin D intake.

“We do get vitamin D from the sun, but it requires prolonged exposure with bare skin exposed, neither of which are often practical or safe in regards to skin cancer. Food sources such as liver, fortified milk, mushrooms and wild-caught salmon have some D but typically not enough to maintain a normal level,” Block told MedTruth. Folks with darker skin tones and people living in places with less sun may need to rely on dietary and supplementary sources to get enough vitamin D.

Lanham-New said that a well-balanced diet is typically how she encourages folks to achieve proper vitamin requirements, but vitamin D is a bit unique.

“However, due to the fact that vitamin D is contained in so few foods, vitamin D supplements have their place and are particularly important during the winter months in areas of northern latitude when no vitamin D will be achieved through UVB exposure,” she said.

“Vitamin D is unique,” Lanham-New said. Since vitamin D is technically a prohormone, a substance

produced in the skin during exposure to sunlight, and in smaller doses obtained from food, the winter months in middle to high latitudes have less access to sunlight..

“For most people, dietary intake does not fully supply the body’s vitamin D needs and so vitamin D status declines during the winter. Relatively high prevalence of low vitamin D status globally has been reported over recent decades in a wide range of population groups, including those in low latitude areas (despite the abundance of sunlight) and not necessarily confined to winter. This may be due to environmental factors, such as air pollution, as well as cultural factors that lead to skin being covered and not subject to sunlight exposure. Older, house-bound individuals are at particularly high risk of vitamin D deficiency,” Lanham-New said

Melbourne, UK-based dietician Helen Bond disagrees about the benefits of vitamin D supplementation.

Bond told MedTruth that most of the vitamin D we are exposed to is through ultraviolet rays from sunlight.

“Taking too many vitamin D supplements over a long period of time can cause too much calcium to build up in the body (hypercalcaemia). This can weaken the bones and damage the kidneys and the heart,” Bond said. The best option in understanding vitamin deficiency is to visit your general practitioner and get tested before taking too many vitamins at once.

Vitamin D and COVID-19

“The discovery of the expression of nuclear vitamin D receptors and vitamin D metabolic enzymes in immune cells provides a scientific rationale for the potential role of vitamin D in maintaining immune homeostasis,” Lanham-New said.“However, there is currently insufficient robust scientific evidence to support claims that high dose vitamin D supplementation will be effective in preventing or treating COVID-19 disease.”

Lanham-New said that everyone should adhere to their government’s guidance on vitamin D supplementation. For folks self-isolating with no sun exposure, supplements are advised. Regardless of the concrete connection between the vitamin and COVID-19, Lanham-New said that the supplement is beneficial.

Recommended vitamin D dosing for adults is 600 IU daily and for those older than 70, it’s 800 IU. Harvard Health warns against taking more than 4,000 IU in a day, unless recommended by your physician, as it can eventually lead to high calcium levels, bone loss, and kidney failure.

Guidance for Those Concerned About COVID-19

Vitamin D plays an important role in maintaining a balanced and healthy immune system. Preliminary evidence also suggests that vitamin D may play a role in COVID-19 infection and mortality rates, but more research is needed. Practicing social distancing, washing your hands and following public health recommendations are still the best ways to avoid falling ill.

For more information about preventing infection with COVID-19, please refer to the U.S. Centers for Disease Control and Preventionrecommendations and/or check with your state and local health departments.

By S. Nicole Lane

S. Nicole Lane is a freelance journalist based in the southside of Chicago where she covers women’s health, the LGBTQ voice, arts, and entertainment. Her byline can be found in Playboy, Rewire News, i-D, Broadly and various other corners of the internet. She is also a visual artist who works with small-scale sculptures.

Medically Reviewed by Benjamin Duong

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