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Can Vitamin D Prevent COVID-19?

Enjoying the sun
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Key Takeaways

  • Vitamin D is important for maintaining a strong immune system.
  • Preliminary studies suggest a possible link between vitamin D deficiency and COVID-19 mortality rates.
  • Risk factors for vitamin D deficiency are also risk factors for COVID-19 infection.
  • More research is needed to draw medical conclusions about the relationship between vitamin D and COVID-19.

Headlines promoting preventative measures and possible treatments for COVID-19 are dominating the news. One popular claim making waves is the potential use of vitamin D as a way to minimize your risk of contracting the disease and also to reduce the severity of the illness should you get it. But it is important for consumers to understand the research behind the headlines before making decisions about taking supplements or consuming extra vitamin D.

What Is Vitamin D?

Vitamin D is a fat-soluble vitamin found in some foods that you consume. For example, fatty fish such as salmon, tuna, and mackerel are good sources of vitamin D. Some foods (such as certain dairy products, breakfast cereals, and orange juice) have vitamin D added.

The fact that this nutrient is fat-soluble means that you need to consume fat to absorb it. The vitamin is dissolved in fats or oils and can be stored in the body's fatty tissue.

One of the primary ways we absorb vitamin D is through sun exposure. The UVB rays trigger a response in your cells to produce vitamin D for your body to use. If you are light-skinned you should aim to get at least 15 minutes of direct sunlight, but if you have dark skin you'll want to get a couple of hours of exposure for adequate absorption.

What Does Vitamin D Do?

Vitamin D plays several important roles in the body. It helps the body to absorb calcium to maintain good bone health, helps to modulate cell growth, and helps transmit messages between nerves and muscles.

Vitamin is also important for proper immune health. The vitamin helps to reduce inflammation in the body by fighting off bacteria and viruses. For this reason, some people pay attention to their vitamin D levels when trying to fight off illness.

According to researchers, low vitamin D levels are associated with certain non-communicable diseases and with increased susceptibility to infectious disease, particularly upper respiratory tract infections.

In fact, a 2017 review published in the British Medical Journal showed that vitamin D supplementation was safe and protected against acute respiratory tract infections. The meta-analysis included data from 11,321 participants in 25 randomized controlled trials. Those with markers of very low vitamin D status showed the greatest benefit.

Vitamin D and COVID-19

Several preliminary studies have suggested that there may be a relationship between vitamin D levels in different populations and COVID-19 infection and mortality rates. But research is limited and so far not enough is known about the relationship to draw firm conclusions.

For example, a study published in the Irish Medical Journal reported that European countries with higher rates of vitamin D deficiency have shown higher rates of COVID infection and mortality. But they can't draw conclusions as to whether this proves there is a cause-and-effect relationship.

In fact, researchers note that risk factors for vitamin D deficiency (male gender, advanced age, pre-existing chronic conditions) are also risk factors for COVID-19. Study authors suggest that optimizing vitamin D levels according to national and international recommendations may provide benefits in boosting bone health and COVID-19 management.

In another widely-publicized study (that has not yet been peer-reviewed), researchers found an association between low vitamin D levels and higher risk for hypercytokinemia or cytokine storm. Study authors call for more research to understand the relationship between the vitamin and this common complication of COVID-19.

Other medical sources are suggesting that vitamin D may play a role in the treatment or prevention of COVID-19. But most study authors note that research is in its early stages and call for ongoing investigations.

Authors of a study specifically suggest that more dedicated research is warranted because vitamin D has already been shown to safety protect against acute respiratory infections and because the most vulnerable population for COVID-19, the aging population, is also the one that has the most deficient vitamin D levels.

How to Maintain Proper Vitamin D Levels

Vitamin D recommendations vary by age. Adults under the age of 70 are advised to get 15 mcg (or 600 IU) of vitamin D per day. If you are 71 years of age or older, 20 mcg (or 800 IU) is recommended.

Vitamin D Testing

A blood test can tell you if your vitamin D levels are sufficient. A serum 25-hydroxyvitamin D level test is the initial diagnostic test in patients at risk for deficiency. But testing for vitamin D levels is a subject of much debate.

Many experts agree that population-wide screening in patients at low risk with no symptoms is not likely to provide a significant benefit. However, there are circumstances where testing makes sense.

Dr. Daniel Culver, DO, is a pulmonary & critical care physician at Cleveland Clinic. He says most individuals, especially those living in areas with low sun exposure or who have diets low in vitamin D, should be tested. Studies have also suggested that suspicion of certain conditions including rickets, osteomalacia (softening of the bones), hyper- and hypoparathyroidism, or chronic kidney disease (CKD) warrants testing.

Signs of Deficiency

You may experience symptoms if you are deficient in vitamin D. Dr. Culver says that symptoms may include fatigue and achiness. The Cleveland Clinic also notes that muscle weakness, muscle aches, or muscle cramps and mood changes, like depression, can be symptoms of vitamin D deficiency. Dr. Culver adds that if you are deficient in vitamin D, you are also likely to have low calcium levels.

In severe cases, vitamin D deficiency can cause rickets in children, although the condition is rare in the United States. In adults, a deficiency can lead to osteomalacia, a condition that causes bone pain and muscle weakness.

How to Get More Vitamin D

There are different ways to maintain proper vitamin D levels in the body.

Consume Vitamin D Rich Foods

Vitamin D foods include fatty fish (salmon, tuna, and mackerel), beef liver, cheese, egg yolks, and mushrooms. You can also increase your intake of vitamin D by consuming fortified foods, such as orange juice, yogurt, milk, breakfast cereals, and other foods that specifically state that they have vitamin D added.

Sun Exposure

Sun exposure is another way to get more vitamin D. Most people meet at least some of their recommended daily intake through direct sun exposure. Sunlight through a window does not produce vitamin D in the body. Shade, clouds, and dark-colored skin also reduce the amount of vitamin D the body makes.

Studies suggest that vitamin D produced through sun exposure may last at least twice as long in the blood compared with vitamin D consumed in food or supplements. According to one study, when an adult wearing a bathing suit is exposed to one dose of UV radiation that produces a slight pinkness to the skin, the amount of vitamin D produced is equivalent to ingesting between 10,000 and 25,000 IU.

But of course, sun exposure comes with an increased risk for skin cancer. Experts advise that you wear sunscreen to decrease this risk.

Vitamin D Supplements

Vitamin D supplementation is recommended for certain people, but not for the general population. According to Dr. Culver, sometimes supplementation makes sense, but communication with your healthcare provider is the smartest approach.

Daniel Culver, DO

Low levels of vitamin D supplements are probably not harmful, and for some individuals may be useful. However, it would be a mistake to think that these are adequate for everyone. If there are any concerns, discussion with your health care provider is suggested. Higher doses may be needed.

— Daniel Culver, DO

Dr. Culver also notes that it is possible to get too much vitamin D. He says that even if otherwise-healthy individuals get too much vitamin D it can lead to excessive calcium levels in the blood, kidney stones, renal failure, nausea, and mental status changes. According to the National Institutes of Health, signs of vitamin D toxicity also include nausea, vomiting, poor appetite, constipation, weakness, and weight loss, and arrhythmia.

What This Means For You

While it is tempting to try to reduce your potential COVID-19 risk by increasing your intake of vitamin D, it is too soon to tell if it will provide any benefit in the prevention or treatment of the disease. Dr. Culver notes that the studies are not definitive and there could be other factors that explain study outcomes. In short, he says we do not yet have proof that vitamin D supplementation would help prevent or ameliorate COVID-19.

If you have concerns about your vitamin D levels, speak to your healthcare provider. Discuss your symptoms, your lifestyle habits (including food intake and sun exposure) as well as your health history. A brief conversation can help you to make the best decision for optimal health and disease prevention.

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Article Sources
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Additional Reading
  • Culver, Daniel, D.O. (2020, June 4). Email interview