Three new studies have reported the positive role of vitamin D in preventing COVID-19 and reducing the severity of illness in hospitalized patients with COVID-19 infection.
Researchers at Boston University conducted a retrospective, observational analysis1 of over 190,000 U.S. patients from 50 states with SARS-CoV-2 results performed mid-March through mid-June, 2020 and who had 25(OH)D (vitamin D) results from the preceding 12 months. Residential zip code data was matched with U.S. Census data to perform analyses of race/ethnicity proportions and latitude.
Vitamin D Deficiency Associated With 54 Percent Higher Risk for COVID-19
Those who had a circulating level of 25(OH)D below 20 ng/mL had a 54 percent higher positivity rate compared to those who had a blood level of 30–34 ng/mL. The risk of SARS-CoV-2 positivity continued to decline until the serum levels reached 55 ng/mL. The inverse relationship between SARS-CoV-2 positivity and 25(OH)D levels was most striking in predominately black non-Hispanic zip codes, followed by predominately Hispanic zip codes.
Calling the results “remarkable,” researcher Michael Holick, MD, PhD, summarized, “If you’re vitamin D deficient, you have a 54 percent higher risk of acquiring this infection compared to people who were vitamin D sufficient,” he said. “This was for all ages, for all ethnicities and for all latitudes in the United States in all 50 states. So whether you’re in California, Florida, or Alaska this still remained the same.”2
Vitamin D Supplementation Can Maintain Healthy Levels of Vitamin D
Approximately 42 percent of the US population is vitamin D deficient3 but 82 percent of blacks and 61 percent of Hispanics are deficient,4 and 60 percent of nursing home residents are deficient.5 Dr. Holick says that vitamin D insufficiency is very common in sunny states like California and Florida because of sunscreen use and the fact that people avoid the midday sun when UVB rays trigger a reaction in skin cells that makes vitamin D. He states that supplementation is a safe and effective way to maintain healthy levels of vitamin D, and that infants need 400-1000 units a day, children 600-1000 units a day, and teens and adults need 1500-2000 units a day, but “if you’re obese you need two to three times more.”6
Vitamin D Status Can Affect Risk of Mortality from COVID-19
A second study,7 also co-authored by Dr. Holick, is a cross sectional analysis of 235 hospitalized patients infected with COVID-19 that found those with sufficient vitamin D status had significantly better outcomes. Of patients over 40 years of age, 9.7 percent of patients who were vitamin D sufficient died compared to 20 percent who were vitamin D insufficient or deficient. Only 6.3 percent of the patients over 40 years died with a blood level of 25(OH)D of 40 ng/mL or higher. The data analyses also revealed that the severe decrease in infection was less prevalent in patients who had sufficient levels of vitamin D. The authors suggest that anti-inflammatory role of vitamin D helps modulate the immune response by reducing the risk for cytokine storm in response to this viral infection.
A pilot study conducted in Cordoba, Spain, and published in the Journal of Steroid Biochemistry and Molecular Biology found that the administration of high dose calcifediol (a main metabolite of Vitamin D endocrine system) significantly reduced the need for ICU treatment of patients requiring hospitalization due to proven COVID-19.8
The study evaluated 76 consecutive patients hospitalized with COVID-19 infection and randomly assigned two thirds of the patients to receive oral calcifediol in addition to standard care (per hospital protocol). One third of the patients received only standard care.
Of 50 patients treated with calcifediol, one required admission to the ICU (2 percent), while of 26 untreated patients, 13 required admission (50 percent). Of the patients treated with calcifediol, none died, and all were discharged without complications. The 13 patients not treated with calcifediol, who were not admitted to the ICU, were discharged. Of the 13 patients admitted to the ICU, two died and the remaining 11 were discharged.
The study authors suggested that activation of the vitamin D receptor (VDR) signaling pathway may generate beneficial effects in acute respiratory distress syndrome (ARDS) by decreasing the cytokine/chemokine storm; regulating the renin‑angiotensin system; modulating neutrophil activity and by maintaining the integrity of the pulmonary epithelial barrier; stimulating epithelial repair, and tapering down increased coagulability of the blood.