Research Blog

April 18, 2020

COVID-19 & Vitamin D Deficiency

Behind every bad disease… is there a good nutrient missing? part 1 - Vitamin D

Dr. Dicken Weatherby & Beth Ellen DiLuglio

The global coronavirus COVID-19 pandemic has mobilized essential healthcare workers to fight the virus on the frontlines. Unfortunately, as of yet there is no definitive curative treatment. These 2 research blog posts are summaries of two published articles exploring the relationship between deficiencies of essential nutrients and immune compromise.

In part 1, we discuss vitamin D deficiency as it relates to immunity. Part 2 will take a look at Vitamin C.

Vitamin D

In the April 2020 article “Evidence that Vitamin D Supplementation Could Reduce Risk of Influenza and COVID-19 Infections and Deaths” published in Nutrients, researchers explore vitamin D’s role in not only reducing risk of COVID-19 infection, but its efficacy in controlling inflammation and reducing viral replication rate.

Characteristics of COVID-19 include increased pro-inflammatory cytokines, elevated C-reactive protein, increased pneumonia risk, sepsis, acute respiratory distress syndrome (ARDS), and heart failure. Individuals with preexisting cardiovascular disease, hypertension, diabetes, chronic respiratory disease, and exposure to air pollution from combustion sources appear to be most at risk for severe disease. Additional observations include obesity as a high-risk factor. Race also appears to be a factor in mean serum 25(OH)D concentrations and COVID-19 incidence and severity. For individuals over 40 years old, mean 25(OH)D for non-hispanic whites was ~25-26 ng/mL; 14-17 ng/mL for non-Hispanic blacks; and 18-22 ng/mL for Mexican Americans. Severe cases of COVID-19 appears to be more common African Americans and Hispanic individuals than in whites.

Research suggests that vitamin D status may be relevant in mitigating some of COVID-19 characteristics and risk factors. Researchers emphasize several important points regarding vitamin D and its role in immunity and inflammation:

  • Deficiency of vitamin D can contribute to ARDS, a life-threatening complication associated with severe COVID-19.
  • Deficiency is more common in the elderly who are more at risk for COVID-19 and influenza, and more common in the winter due to limited exposure to sunlight which converts the cholesterol compound 7-dehydrocholesterol to pre-vitamin D in the skin.
  • Vitamin D plays a vital role in immunity via:
    • Maintenance of tight junctions, gap junctions, and adherens junctions, physical barrier points of entry vulnerable to viruses and other microorganisms.
    • Induction of anti-microbial peptides such as cathelicidin and defensins.
    • Modulation of the characteristic cytokine storm via inhibition of pro-inflammatory compounds (e.g. TNF-alpha, interferon-gamma) and support of Th2 and T regulatory cells.
    • Vitamin D enhances production of glutathione which in turn spares antimicrobial vitamin C (ascorbic) acid. Vitamin C has been proposed as a preventative and treatment measure for COVID-19.

Vitamin D supplementation

A controlled clinical trial of high-dose vitamin D3 in ventilated ICU patients with a mean baseline 25(OH)D concentration of 20-22 ng/mL demonstrated a reduction in length of hospital stay with a statistical significance of p=0.03. Subjects were supplemented with either 250,000 or 500,000 IU of vitamin D3.

Postmenopausal women with a mean baseline 25(OH)D experienced significantly less influenza and upper respiratory tract infections when taking 2000 IU vitamin D3 per day than either placebo or those receiving 800 IU/day.

Former CDC director Dr. Tom Frieden has proposed use of vitamin D in the fight against COVID-19. Researchers recommend achieving serum 25(OH)D concentrations of at least 40-60 ng/mL (100-150 nmol/L). Supplementation of 10,000 IU vitamin D3 daily for two weeks, followed by 5,000 IU daily should reduce risk of infection. Higher doses may be needed for those already infected by SARS-CoV-2, the virus responsible for the current pandemic.

Note that several medications can reduce serum 25(OH) vitamin D including antiepileptics, antineoplastics, antibiotics, anti-inflammatory agents, antihypertensives, antiretrovirals, endocrine drugs, and some herbal medicines.


Grant WB, Lahore H, McDonnell SL, et al. Evidence that Vitamin D Supplementation Could Reduce Risk of Influenza and COVID-19 Infections and Deaths. Nutrients. 2020 Apr 2;12(4).
Tag(s): Treatment

Other posts you might be interested in