Skip to content

I'm a Doctor and This Vitamin May Reduce Your COVID Risk

Here's why to consider taking vitamin D in the age of COVID-19.

As a doctor, I have been scratching my head and thinking hard about what on earth we can do to help ourselves to beat coronavirus. One answer may lie in a simple vitamin: Vitamin D. "If you are deficient in vitamin D, that does have an impact on your susceptibility to infection," said Dr. Anthony Fauci, the nation's top infectious disease expert. "So I would not mind recommending, and I do it myself taking vitamin D supplements." Read on to the end to see if you need more of this important vitamin, and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had Coronavirus.


How Does Vitamin D Help Fight COVID-19?

Nurse holding test tube with blood for 2019-nCoV analyzing. Novel Coronavirus blood test

"Low levels of vitamin D may put people at risk for developing COVID-19, according to a new study by Leumit Health Care Services and Bar-Ilan University's Azrieli Faculty of Medicine," reports the Jerusalem Post. "The main finding of our study was the significant association of low plasma vitamin D level with the likelihood of COVID-19 infection among patients who were tested for COVID-19," say researchers. "Furthermore, low vitamin D level was associated with the risk of hospitalization due to COVID-19 infection."

Have you thought about vitamin D? Up to 60% of the US population are estimated to have low levels of vitamin D. Could you be one of them? Should you consider a vitamin D supplement? Let's start with the basics.


What Is Vitamin D?

Natural sources of vitamin D and Calcium

Vitamin D is an essential vitamin—essential because our bodies can't exist without it. There are two forms of vitamin D: D2 and D3.

  • Vitamin D2 comes from the diet—it's found in oily fish, egg yolks, red meat, liver, some fat spreads, and fortified cereals. Dietary intake of vitamin D2 is vital because we cannot synthesize this in our bodies. Many people just don't like eating these foods, and do not take in enough vitamin D2.
  • Vitamin D3 is made in the skin in response to sunlight—UVB radiation. However, many of us are also deficient in this too. This occurs especially in the winter, when the days are short and dark. Also, using SPF factor 30 sunscreen—imperative for skin cancer protection—reduces skin absorption of UVB by 95%.

It may not be a coincidence that seasonal flu and other respiratory infections peak in the winter months.


How Common Is a Vitamin D Deficiency?

Young exhausted,depressed,concentrated woman sitting in her room or office with french windows in the dark at the lamp

50% of the world are vitamin D deficient. It affects one billion people around the globe. How could this be? Here's a partial list of reasons:

  • Social/cultural – Fewer people work outdoors these days for long periods. Plus peoples' eating habits have changed.
  • Skin color –The increased amounts of melanin in darker skin absorb greater quantities of UVB. Darker-skinned people need more UVB exposure than fairer skinned people to achieve adequate vitamin D levels. 
  • Older people – In the US, 60% of people in nursing homes and 57% in the hospital are vitamin D deficient. They may only go outside infrequently, tend to wear long-sleeved clothes, and cover up more—plus they may have a small appetite, or eat a poor diet.
  • Babies, children, pregnant and breastfeeding women – They all have increased vitamin D requirements and intake may not match demand.


What Does Vitamin D Do?

Digital composite of Highlighted leg bones of jogging woman on beach

Vitamin D has two important roles:

1. Calcium and Phosphorus Metabolism

Vitamin D increases blood levels of calcium and phosphorus. It also regulates osteoblastic (bone-building) and osteoclastic (bone-clearing) activity. It is used to prevent and treat osteoporosis. However, mega-doses of vitamin D are not advised. It should be used within the recommended dosage.

2. Supporting the Body's Defense Mechanism Against Infection

Vitamin D has many complex effects on the body's defense mechanisms. It plays a role in maintaining the barrier function of the skin and at other epithelial cell surfaces. It is also involved in innate immunity – this is your body's ability to recognize and destroy an invading organism. Vitamin D also plays a role in adaptive immunity – the way your body produces an antibody response.


Why Does Vitamin D Deficiency Matter?

In the Hospital Operating Room Anesthesiologist Looks and Monitors and Controls Patient's Vital Signs, Nodding to a Chief Surgeon to Proceed with Surgery.

Evidence is accumulating of the potential health risks associated with low levels of vitamin D. It must be stressed that these are observational studies—studies which report data that have been collected in specific populations/situations—and that just because these statistics have been observed, that does not prove causation. More research is needed. However, the links between low levels of vitamin D, and many different diseases are still relevant, and of great public health interest.

In 2017, the journal PLOS One, reported a meta-analysis of 26,916 participants, regarding vitamin D and mortality. The authors concluded that people with low blood levels of vitamin D —less than 30 nmol/L—had significantly higher mortality than those with recommended levels of 75-99.9 nmol/L.

RELATED: COVID Mistakes You Should Never Make


What Are the Health Problems if You Don't Consume Enough Vitamin D?

woman in bed suffering from cancer

Vitamin D deficiency has been reported:

  • To increase the risk of cancer of the breast, prostate and bowel, by 30-50%.
  • To increase the risk of cardiovascular disease. Vitamin D stimulates the production of nitric oxide and helps prevent oxidative stress. There appears to be a link between low levels of vitamin D and high blood pressure. Vitamin D may have an anticoagulant effect. It may also have a role in reversing atherosclerosis.
  • To increase the risk of the onset of diabetes. Vitamin D deficiency is associated with insulin resistance, and with pancreatic cell function.
  • To effect brain function. Vitamin D works a neurotransmitter and also has a protective role for brain tissue. Vitamin D deficiency has been linked to a higher risk of depression, Alzheimer's disease and epilepsy.

Of note, other studies have reported reduced mortality in people taking vitamin D supplements.


How to Increase Your Vitamin D Levels

salmon filet
  1. Eat foods rich in vitamin D, like fatty fish (tuna, salmon); foods fortified with vitamin D, like some dairy and cereals; cheese; eggs (the yolks); beef liver and any of these.
  2. Expose your skin to sunlight, without sunscreen. For fair-skinned people 15-20 minutes per day. For darker-skinned people 20-40 minutes per day.
  3. Consider taking a vitamin D supplement.


How Much Vitamin D Supplement to Take?

Man sitting at the table and taking vitamin D

The Mayo Clinic "recommends that adults get at least the RDA of 600 IU. However, 1,000 to 2,000 IU per day of vitamin D from a supplement is generally safe, should help people achieve an adequate blood level of vitamin D, and may have additional health benefits."


Are Vitamin D Supplements Safe?

Back view of woman making video call with her doctor while staying at home. Close up of patient in video conferencing with general practitioner on digital tablet. Sick girl in online consultation.

For the vast majority of people, if you take vitamin D supplements within the recommended levels, it is safe. However, as with any new regular medication/supplement, if you have any medical conditions or take any other medicines, you are strongly recommended to discuss this with your doctor in advance. It is possible to have a blood test to check your vitamin D levels—however, this is rarely felt to be necessary. 

RELATED: Everything Dr. Fauci Has Said About Coronavirus


What Are the Side Effects of Vitamin D?

young woman scratching her arm with allergy rash

Vitamin D is well tolerated and side effects are uncommon. The most common side effects are skin rashes or urticaria, aka hives. The most serious side effect is hypercalcaemia—a raised calcium level—but this is only possible when you take high levels of vitamin D for long periods and is very rare. If you know you have high calcium levels already, do not start vitamin D supplements.

Signs/symptoms of vitamin D toxicity include

  • Anorexia
  • Vomiting
  • Fatigue
  • Weakness
  • Thirst
  • Frequently passing urine
  • Constipation

If you take vitamin D supplements and develop these symptoms, you must see your doctor without delay.


Who Should Not Take Vitamin D Supplements?

At doctors appointment physician shows to patient shape of kidney with focus on hand with organ. Scene explaining patient causes and localization of diseases of kidney, stones, adrenal, urinary system - Image

Do not take vitamin D supplements if you have:

  • Hypercalcemia (too much calcium in your blood)
  • Severe kidney disease
  • Kidney stones
  • Heart disease – and/or take digoxin
  • Sarcoidosis
  • Allergy to vitamin D, or any vitamin D products
  • Other allergies —some vitamin D drops contain peanut oil, aspartame, and other substances, such as food colorings and dyes. Check the product ingredients carefully.
  • Check with your doctor before taking any supplements.


Are There Any Drug Interactions With Vitamin D?

Steroids for physical development of human body as medical's pills.
  • Anticonvulsants – enzyme-inducing e.g. carbamazepine, phenytoin, topiramate, and non-enzyme inducing e.g. gabapentin, lamotrigine
  • Benzodiazepines – e.g. diazepam, nitrazepam
  • Steroids – e.g. prednisolone taken by mouth
  • Digoxin – there is a risk of digoxin toxicity
  • Cholestyramine – this prevents vitamin D absorption
  • Actinomycin –this possibly inhibits vitamin D absorption from the gut
  • Imidazole – this inhibits activation of vitamin D in the kidney

This list is not exhaustive. If you take regular medication, always check with your doctor or pharmacist before you start to take any additional medicines.


How to Take Vitamin D Supplements

vitamin d
  • Vitamin D is available as a tablet, capsule, soft gel, or as drops.
  • Choose the preparation/brand which suits you best and the appropriate recommended dosage. There is no benefit from taking large doses of vitamin D and this may be harmful, so do not be tempted to exceed the recommended dose.
  • Take care because not all vitamin D products contain the same amount of vitamin D – cholecalciferol. In one 2013 study, published in the Journal of the American Medical Association, researchers tested various vitamin D brands and found the potency of cholecalciferol varied from 9 – 146% of the stated dose. Only one manufacturer supplied a product within 90 – 120% of the expected potency. 


How to Choose Best Vitamin D Product for You?

woman with medicine jars at home

When choosing a vitamin D product, always look at the back of the packaging and check the product is USP verified. This means the products have been rigorously tested and the ingredients have been verified. 

  • Vitamin D options are available for vegans.
  • Take vitamin D just before a meal. This is a fat-soluble vitamin and if you take it on an empty stomach is unlikely to be absorbed.
  • You generally take vitamin D once a day—either in the morning or at night. If you don't eat breakfast, take in the evening, just before your evening meal.
  • There is a suggestion that vitamin D may interfere with melatonin production, although there is no evidence it affects sleep, however you may prefer to take it in the early evening.
  • Make sure you always drink plenty of fluids.
  • If you forget your daily dose, miss it out that day, and take it on time the next day.


Vitamin D, Respiratory Infections, and COVID-19

man wearing air filter mask having Dyspnea, breathing difficulty, respiratory distress in unhealthy, danger, polluted air environment

UK scientists have warned that you should not take high levels of vitamin D for the purpose of preventing or treating COVID-19. However, some experts are suggesting the reverse. 

In a publication from March 2020 in the journal Nutrients, the authors reviewed the current medical evidence and suggested that vitamin D supplementation might reduce the risk of influenza, COVID-19, and deaths.

They presented evidence to suggest that higher levels of vitamin D in the population would reduce the risk of acute respiratory tract infections including influenza, COVID-19, and pneumonia. They also suggested that additional vitamin D should be started now, to raise levels before the onset of the winter.

But on the contrary, UK scientists warn that caution is needed. The currently available evidence comes from observational studies only which do not prove causation. Furthermore, high levels of vitamin D can be harmful. 

RELATED: I'm a Doctor and Here's When You Can Safely Keep Your Mask Off


Final Thoughts From the Doctor

Happy Beautiful Girl With Pill With Cod Liver Oil Omega-3

The issue of vitamin D deficiency and the threat of COVID-19 was recently discussed in the New York Times. They reached a sensible conclusion—that those who cannot obtain enough vitamin D from their diet should consider a supplement of 1000-2000 IU/day.

It seems to me that vitamin D deficiency is so common, supplementation is safe, and may indeed have numerous understandable benefits for our overall health. This is something relatively easy we can do, which is likely to be beneficial and not harmful for ourselves and those we love. Whether or not it will help protect us from COVID-19 is unknown—but maybe … just maybe? Furthermore, to get through this pandemic at your healthiest, don't miss these 35 Places You're Most Likely to Catch COVID..

Dr. Deborah Lee is a medical writer for Dr Fox Online Pharmacy.

Deborah Lee, MD
Dr. Deborah Lee is a health and medical writer with an emphasis on women's health. Read more about Deborah