Can Vitamin D Prevent or Ameliorate Covid-19 Infections?
Previous research has reported that vitamin D can increase the incidence and severity of infectious diseases like influenzas or the common cold. The question remains as to whether this applies to Covid-19 infections.
The primary role of vitamin D is to aid the absorption of calcium and phosphorus for bone formation and muscle function. A deficiency can also increase the risk of chronic inflammation, a common cause of several major chronic diseases.
Vitamin D is produced to its most active form from cholesterol in skin cells upon exposure to ultraviolet rays from the sun.
Inadequate vitamin D status is common. It is reported that vitamin D deficiency can be common in the elderly, homebound or darker skinned individuals. Obesity is another risk factor for severe COVID-19 and low levels of vitamin D are commonly found in these patients.
Another primary function of Vitamin D is known to reduce inflammation and can stimulate the release of anti-microbial proteins that kill viruses and bacteria. A study at Northwestern University suggests that vitamin D could suppress what is known as the “cytokine storm” that has been reported be fatal in some coronavirus patients.
People are scrambling to the supplement stores for vitamin D, but there are certain caveats to supplementation at high doses of any supplement on the market, including vitamin D. Here is what you should know about its efficacy and/or safety.
It can become very easy to be deficient in vitamin D since it is found in very few foods like fatty fish, egg yolks and fortified milk (not commonly found in the highly processed Standard American Diet).
It is recommended that people ask their doctors for a blood test to determine their vitamin D status. Deficiency is defined as a blood level below 10 nanograms per milliliter. Blood levels of 20-50 nanograms per milliliter are generally considered normal.
The Institute of Medicine recommend that most adults get 600 International Units (IU) of vitamin D from food and supplements daily or 800 IU if they are 70 years or older. Most experts agree that D is safe at doses up to 2000 IU and that 4000 IU a day is established as the Tolerable Upper Intake. The dose you take should be established by your physician and your blood levels. Toxicity is possible with long-term use of 10,000 IU daily.
The consequences of overdose include:
- Mental retardation in young children
- Abnormal bone growth and formation.
- Nausea, diarrhea, irritability, weight loss.
- Deposition of calcium and organs such as the kidneys, liver and heart.
What the Research Shows
A recent study at the University of Chicago reviewed the medical records of about 4300 patients who had been tested for COVID-19 early last spring. After controlling for factors like age, race, and chronic medical illness, they found that people with a vitamin D deficiency before the pandemic began were 77% more likely to test positive for COVID-19 compared to people who had normal levels of vitamin D.
Other studies have mixed results, however some researchers feel that there is enough compelling evidence to suggest that a randomized trial is needed to specifically test to see whether assigning people to take vitamin D every day will reduce the severity of their illness, if infected. People are bombarded recently with supplement companies promoting high doses of vitamin D – trials are also needed for consumers to make intelligent and safe choices regarding their health.
Judith E. Brown, Nutrition Now. 7th Edition
Anahad O’Connor, Exploring the Links Between Coronovirus and Vitamin D. The New York Times, June 10, 2020.