Deficient in Vitamin D? You May Face a Higher Risk for COVID-19

The issue of vitamin D deficiency, a long-overlooked public health concern, has been getting more attention as a potential indicator for coronavirus disease 19 (COVID-19) risk. The findings of recent research have suggested a link between vitamin D deficiency to COVID-19 risk. In one study, researchers looked back at hospitalization and patient data from the first wave of the pandemic. They found that almost 60% of patients admitted to the hospital with COVID-19 were deficient in vitamin D, and those patients were 3.7x more likely than other patients to die from complications of the disease.1 While the evidence is compelling and merits further investigation, vitamin D deficiency had already been linked to higher rates of death outside of the COVID context.2 As such, the condition is a public health concern on its own – with or without a conclusive link to COVID-19 mortality. Learn more about vitamin D, the potential link to COVID-19, and other important health facts.

What is Vitamin D?

Vitamin D is a fat-soluble hormone that can be consumed or created in the body. This nutrient helps the body absorb and retain calcium and phosphorous – critical building blocks for strong bones. Many of the body’s tissues and organs have receptors for vitamin D – suggesting this nutrient helps support more than just your skeleton.3

Who is Affected by Vitamin D Deficiency?

Nearly half of all people worldwide are considered deficient in vitamin D levels. The deficiency is driven primarily by lifestyle and environmental factors – including low outdoor activity levels, health conditions requiring prolonged periods of hospitalization, and air pollution blocking sunlight.2 Concerning COVID-19, health experts have noted the groups of people who tend to suffer from vitamin D deficiency are the same groups that have been disproportionately impacted by the disease – including older adults, people who live in nursing homes, and minority ethnic populations. Stay-at-home rules and increased time spent indoors have also sparked concerns that people are spending sufficient amounts of time in the sun.

What Are the Sources of Vitamin D?

With vitamin D deficiency being so common and affecting all age groups, it is essential to pay attention to vitamin D intake. There are several sources of vitamin D:

Sunshine

Getting outside can help ensure you are getting enough vitamin D. The body makes this nutrient when bare skin is exposed to sunlight. Between 50% and 90% of vitamin D comes from sunlight absorbed through the skin. Health experts recommend getting at least 20 minutes of sunshine each day with more than 40% of skin exposed to help avoid vitamin D deficiency.4

Food Sources

Vitamin D, unlike most nutrients, is not commonly found in foods. Most foods known to contain vitamin D are fortified before being sold – meaning vitamin D is added during the manufacturing process. Natural and fortified foods that contain vitamin D include:3 Milk. Most of the US’ milk supply is fortified with a certain amount of vitamin D per cup. Plant-based milk alternatives, such as soy milk, almond milk, and oat milk, are also fortified. It is important to note that milk-based products like cheese and ice cream are typically not fortified with vitamin D.
Breakfast foods. Vitamin D is added to many different brands of breakfast foods, including cereal, yogurt, and orange juice. Fatty fish. Certain fish, including tuna, salmon, trout and mackerel, and fish liver oils are excellent sources of natural sources of vitamin D. Other foods. Mushrooms, beef liver, and egg yolks are known to contain small amounts of vitamin D. The best way to know your food or beverage’s vitamin D content is to read through the nutrition label.

Supplements

Vitamin D can be purchased as multivitamin or multimineral supplements and dietary supplements containing only vitamin D or vitamin D combined with a few other nutrients. D2 (ergocalciferol) and D3 (cholecalciferol) are the two forms of vitamin D in supplements. Because vitamin D is fat-soluble, it is best absorbed when taken with a meal or snack that includes some fat.

Potential Side Effects of Vitamin D

While vitamin D is touted as an immunity booster and is generally considered safe, too much of the nutrient can cause harm. Taking more than the daily recommended amount of vitamin D can cause:5 Vomiting Nausea Constipation Weakness Confusion Disorientation Loss of appetite and unintentional weight loss Heart rhythm issues Kidney damage

Vitamin D and Health Conditions

Vitamin D is typically linked to bone health, but research has also linked this nutrient to improved infection control, lower inflammation levels, and reduced cancer cell growth. Specifically, evidence suggests vitamin D may help play a role in helping to prevent or improve the following conditions:5 Cancer. Vitamin D, particularly when taken with calcium, may help prevent certain cancers. Cognitive health. Preliminary research has linked vitamin D to improvements in cognitive health and function, including dementia. Multiple sclerosis. Long-term supplementation of vitamin D can help reduce the risk of developing multiple sclerosis. Osteomalacia (“soft bones”). Adults deficient in vitamin D may suffer from loss of bone mineral content, contributing to osteomalacia, bone pain, and muscle weakness. Vitamin D supplementation can help address these conditions. Psoriasis. Vitamin D in topical lotion form or any lotion that contains calcipotriene (a compound in vitamin D) has been shown to help address plaque-type psoriasis in some people. Rickets. Rickets is a rare bone condition affecting children with vitamin D deficiency. Supplementation of vitamin D can help prevent and treat this issue.

COVID-19 and Vitamin D Deficiency: Debate Over Supplements

In the wake of evidence linking vitamin D deficiency and COVID-19 risk, some health experts have publicly recommended taking supplements as a preventive measure against infection. Anthony Fauci, MD, Director of the National Institute of Allergy and Infectious Diseases within the National Institutes of Health, has said he supports vitamin D supplementation to boost immunity. “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,” Dr. Fauci responded during an interview about immune-boosting supplements amid COVID-19.6 On the other hand, recently published guidelines on the subject note the evidence does not sufficiently support a recommendation for vitamin D supplements solely for COVID-19 prevention. The National Institute for Health and Care Excellence in the United Kingdom conducted a rapid review of evidence in response to this hypothesis. Researchers agreed that, across the studies reviewed, low vitamin D status was associated with more severe outcomes from COVID-19. However, they noted it is impossible to confirm causality because many of the risk factors for worse COVID-19 outcomes are the same as the risk factors for vitamin D deficiency.7

Vitamin D: The Bottom Line

Ultimately, supplements are a reliable way to ensure you are getting enough vitamin D, and the habit is widely understood to be generally safe. Taking them to help boost your immunity and prevent severe COVID-19 complications is a wise choice, but it is crucial to know vitamin D is not a “cure.” Taking all other precautions against COVID-19, including social distancing and regular handwashing, remains an important part of preventing disease spread.