Higher blood levels of vitamin D are strongly associated with less severe disease and lower mortality with Covid-19. Vitamin D acts more like a hormone with multiple effects on different organs than a simple vitamin. Of importance, it regulates the renin-angiotensin system and the immune system, both of which are critical determinants of the body’s response to Covid-19. Vitamin D reins in inflammatory responses and reduces the cytokine storm that contributes to severe outcomes. It is widely recognized for its protection against viral lung diseases and improvements in immune responses.
Vitamin D’s protection arises from producing compounds that reduce viral multiplication and reduce inflammatory cytokine levels for less injury to the lungs and other organs. Vitamin D also increases levels of anti-inflammatory cytokines like interleukin-10 (IL-10).
At least half of adults in the U.S. are deficient in vitamin D, especially during the winter months. More significant deficits occur in African American and Hispanic populations, the elderly, those overweight, smokers, and diabetes.
A few of the studies suggesting that Vit D supplements reduce the risks posed by Covid-19 and influenza:
- A Diabetic Medicine report in 2012 reviewed 2001 to 2004 data from a National Health and Nutrition Examination Survey. They found 81% of U.S adults aged 40 and older with diabetes were deficient in vitamin D with levels below 30 ng/mL, the lower limit for normal. Deficiencies were more common among Hispanics (92%) and non-Hispanic black people (98%) than among non-Hispanic white people (76%).
- A November 2020 Belgian study found 59% of patients admitted to the hospital for a Covid infection were deficient in vitamin D on admission. Those deficient were 3.9 times more likely to die during their hospitalization.
- A stunning report from Spain found that only 2% of those started on a rapid-acting prescription form of vitamin D called calcifediol (Calcitriol) on their first day in the hospital with Covid-19 required treatment in the ICU compared to 50% of those who received a placebo.
Researchers gave those treated with Calcitriol IV doses of 0.532 mg (equivalent to 100,000 units of vitamin D3) on the first day in the hospital, 0.266 mg (another 50,000 units) on the third and seventh days, and 50,000 units weekly until discharge or admission to the ICU.
- Ten years ago, researchers studied 198 healthy adults living in or near Greenwich, Connecticut. They found the risk of getting a viral respiratory tract infection was cut in half in those with a serum vitamin D level greater than or equal to 38 ng/mL (p < 0.0001). Their percentage of sick days was also reduced five-fold (p = 0.02), compared to those whose D levels were below 38 ng/mL.
- Before the start of Covid, 23 of 30 mechanically-ventilated patients in a 2018 research study were vitamin D deficient. Over 85% of them were anemic and less able to carry oxygen. Treatment with 100,000 units of OTC vitamin D3 for five days (a total dose of 500,000 units) improved their oxygen-carrying ability.
- Gordon Shotwell, a Canadian data scientist, has collected an excellent Review of Vitamin D and Covid that provides multiple study results and references.
To protect against Covid, build up your vitamin D level ahead of time. The large doses required to correct a deficit typically require intake over about four months. You can also rapidly raise levels with Calcitriol, the prescription form of cholecalciferol.
An adult who is vitamin D deficient requires about 600,000 units to bring blood levels up to mid-normal levels. In adults, correcting deficits may be started with 4,000 units a day for four months and may take longer. The NIH states that a daily intake of 1,000 to 4,000 units a day is safe for adults. Since fat cells store vitamin D, someone overweight requires even higher doses.
To reduce the risk of a Covid-19 infection and its severity, people at risk can consider taking 10,000 units of vitamin D3 each day for seven weeks to raise their vitamin D3 concentration. This dose comes to 490,000 total units. The goal is to raise vitamin D3 concentrations to a level between 40 and 60 ng/mL (100-150 nmol/L). After this loading dose, 2,000 units a day are usually required to maintain this level.