Is there a linear relationship between vitamin D levels and COVID mortality?

New and compelling clinical research further cements the case, and even suggests a baseline level of vitamin D at which there’s theoretically zero mortality from the pandemic disease.

German researchers published the findings in the October issue of Nutrients (2021:13[10]:3596). Specifically, the study looked at mortality among 1,601 patients hospitalized with COVID-19 disease; 784 who had their vitamin D levels measured within a day after admission, and 817 whose vitamin D levels were known before infection. Another data set analyzed the long-term average vitamin D3 levels documented for 19 countries. Combined, researchers determined a median blood serum level of 25(OH)D—a stable vitamin D metabolite used to clinically assess vitamin D status—at 23.2 ng/mL across all the collected study cohorts, an amount considered insufficient.

“At a threshold level of 30 ng/mL, mortality decreases considerably,” the study authors found.

Because the data included vitamin D3 measurements taken before the onset of COVID-19 disease, an argument cannot be made that the disease itself may have triggered the low levels of vitamin D. “The datasets provide strong evidence that low D3 is a predictor rather than just a side effect of the infection,” the authors concluded.

Statistical correlation analysis further identified a theoretical point of zero mortality—when blood level amounts of 25(OH)D reach 50 ng/mL. That level of vitamin D3 in the blood “would save most lives, reducing the impact even for patients with various comorbidities,” the authors asserted.

The German study joins an already robust body of research of more than 150 studies that vouch for the increasingly accepted correlation between higher vitamin D levels and better outcomes in COVID patients. To wit, a recent and notable preprint Israeli study found that a person is 14 times more likely to end up in severe or critical condition from COVID if a vitamin D deficiency is present.

The research around vitamin D furthers the case for wider use of supplements across global populations to combat the impact of COVID-19 disease, something the authors of the German study conclude as well.

“(T)he authors strongly recommend combining vaccination with routine strengthening of the immune system of the whole population by vitamin D3 supplementation to consistently guarantee blood levels above 50 ng/mL,” they wrote. “From a medical point of view, this will not only save many lives but also increase the success of vaccination. From a social and political point of view, it will lower the need for further contact restrictions and lockdowns. From an economical point of view, it will save billions of dollars worldwide, as vitamin D3 is inexpensive and—together with vaccines—provides a good opportunity to get the spread of SARS-CoV-2 under control.”

The vitamin D message

Supplement ingredients that target immune health and system support have surged with consumers since the onset of the pandemic. Vitamin D—along with other category leaders like vitamin C, elderberry and zinc—is trending up with supplement takers, according to the Council for Responsible Nutrition.

CRN’s latest 2021 survey data showed that vitamin D usage in the U.S. rose by 10 percentage points—52% versus 42% in 2020. At the same time, CRN’s survey found that 45% of all respondents indicated they’ve had their vitamin D levels checked by a health care provider at some point during the pandemic.

To bolster the vitamin D message, the CRN Foundation has rolled out a new program, Vitamin D & Me!, which includes a website that provides a compilation of research, news and opinions from medical and research experts on the role of vitamin D and COVID-19.

“Increasing evidence suggests a link between higher vitamin D levels and lower incidence of COVID-19,” said Luke Huber, N.D., MBA, vice president of scientific and regulatory affairs at CRN. “We have known for years that vitamin D plays an important role in immune health, and now there are multiple meta-analyses that appear to demonstrate the benefits of this nutrient in COVID-19.”