COVID research on vitamin D offers clues to formulators

Vitamin D should form the foundation of any immune-support supplement. Here's what new research is showing.

Todd Runestad, Content Director,

June 7, 2020

6 Min Read
Vitamin D_0.jpg

Supplements companies are re-thinking SKUs in response to the COVID-19 pandemic. Some are simply bundling its immunity-focused lines to meet the moment. Others are formulating whole new SKUs, re-thinking the place immune support is playing in its overall portfolio.

Vitamin D in particular is gaining a new surge of interest—and not just because vitamin D has been shown in studies to support a healthy immune function and, specifically, to decrease acute respiratory infections.

COVID research

Incredibly, since April 2, fully 22 studies have been published on vitamin D and covid-19. Currently, 11 formal clinical trials are listed at aimed at testing vitamin D supplementation in COVID-19 patients in combination with other drugs, and comparing high doses versus standard doses.

“Vitamin D is not a specific treatment for COVID-19, it is a treatment for vitamin D deficiency,” said Paul Bergner, director of the North American Institute of Medical Herbalism. “Vitamin D deficiency is highly correlated to the frequency of respiratory infections in general. Vitamin D deficiency is also highly correlated to the intensity of cytokine storms. A vitamin D deficiency also correlates with poorer outcomes in intensive care units generally. A vitamin D deficiency correlates with most known co-morbidities, cardiovascular disease, hypertension, diabetes.”

Related:Optimizing immunity, energy, sleep and nutrition through supplements – podcast

Researchers first began noting a general correlation between low vitamin D levels and incidence of COVID-19 (a correlation noted by numerous other research studies in the past few months).

Researchers in the Philippines who assessed 212 cases of COVID-10 found lowest vitamin D levels in the most critical cases whereas the milder cases had higher vitamin D levels. “Vitamin D status is significantly associated with clinical outcomes,” they wrote. An increase in vitamin D status in the blood “could either improve clinical outcomes or mitigate worst (severe to critical) outcomes, while a decrease in serum 25(OH)D level in the body could worsen clinical outcomes of COVID-19 patients. Vitamin D supplementation could possibly improve clinical outcomes of patients infected with COVID-19.”

Disease severity and death rates are also higher in the elderly, African-Americans, patients with diabetes, and chronic lung and cardiovascular diseases—all groups with low vitamin D levels.

European researchers noted that vitamin D levels are severely low in the aging population especially in Spain, Italy and Switzerland—the most vulnerable group of the population in relation to COVID-19.

Related:Herb hunting in the COVID age – podcast

One provocative correlation is that there is a well-known disparity in COVID-19 prevalence due to racial groups. Black and minority ethnic people, who are more likely to have vitamin D deficiency because they have darker skin, seem to be worse affected than white people.

Researchers in a study published in April noted that vitamin D can reduce the risk of infections through several means. Vitamin D, wrote the researchers, “can lower viral replication rates and reduce concentrations of pro-inflammatory cytokines that produce the inflammation that injures the lining of the lungs, leading to pneumonia, as well as increasing concentrations of anti-inflammatory cytokines.”

These researchers suggested those at elevated risk of infection begin by taking 10,000 IU/day vitamin D for a few weeks, followed by a maintenance dose of 5,000 IU/day.

A follow-up commentary, however, also published in the journal Nutrients, contested that recommendation.

Observational studies, it is true, show vitamin D deficiency is associated with increased risk of infections. In particular, those with larger deficiencies tend to have significantly longer and more severe upper respiratory tract infections.

But the researches in their response noted that the best results—a 12% overall reduction in acute upper respiratory tract infections—was found to have outsized benefit among those with vitamin D blood levels of a significantly deficient 10 ng/dl—half that of even the lowball deficiency level from the National Institutes of Health of 20 ng/dl. These are people who do not go outside in the sun much, nor consume much dietary sources of vitamin D such as fortified milk, egg yolks, cheese or fatty fish like tuna, mackerel and salmon.  

In one of the recent COVID-related studies, researchers suggested vitamin D (as well as melatonin) may play a role by down-regulating the inflammatory response related to the bodily system that regulates blood pressure and fluid balance in the body, called the renin-angiotensin system. Hypertension, or high blood pressure, is one of the co-existing conditions that has consistently been reported to be more common among critical COVID-19 patients.

A Turkish researcher postulated that vitamin D could work against COVID-19 infection-induced multiple organ damage not just by reducing the level of renin but also by decreasing the inflammatory cytokine storm, decreasing other pro-inflammatory markers, and by increasing antimicrobial activity.

How much vitamin D should you formulate with?

The official Daily Value—that is, the minimum amount required to stave off a bone-related deficiency disease like rickets—is a paltry 600 IU/day (800 IU for those over age 70). This recommendation was issued for vitamin D as it relates to only bone health.

Vitamin D has actually shown benefit for a wide range of health states, including immune function. A Harvard School of Public Health review summarized evidence suggesting optimal vitamin D blood levels in relation to bone mineral density, lower-extremity function, dental health, and risk of falls, fractures, and colorectal cancer. Survey said: benefits begin at 30 ng/ml, preferably between 36-40 ng/ml. “In most persons,” wrote the researchers, “these concentrations could not bne reached with the currently recommended intakes of 200 and 600 IU vitamin D/day for younger and older adults.” The concluded that at least 1,000 IU/day would bring 30 ng/ml to half of the population.

Researchers in New Zealand gave pregnant women at the start of their third trimester and their subsequent infants for the first six months of their lives either placebo/placebo, 400/1,000 IU, or 800/2,000 IU vitamin D per day. Only the higher doses of vitamin D led to a significant decrease in acute respiratory infections.

In a study among basic training marines, researchers gave male and female recruits 1,000 IU/day vitamin D plus 2,000 mg/day calcium for 12 weeks. They found the supplements improved markers of immune response during high-stress basic training.

Many holistic practitioners advocate peoples’ serum blood levels of vitamin D for optimal health (not just bone health, as the Institutes of Health would have it) should not be merely 20 ng/ml but rather between 40-60 ng/ml. To that end, studies have shown that a vitamin D intake of 4,000 IU/day and up is required for that level throughout the year.

That suggests that minimum doses of vitamin D should be 1,000 IU, perhaps 2,000 IU/day. And as noted, some researchers believe a maintenance dose as high as 5,000 IU/day is appropriate.

As for COVID-19 concerns specifically, it is of course a disease and of course supplements by law cannot claim to prevent, cure or treat a disease state. That is in the exclusive purview of pharmaceutical drugs. But, information is power, and research teams should be interfacing with marketing in order to develop—and appropriately communicate—immune-health supplements that are both effective and let consumers know all about it.

About the Author(s)

Todd Runestad

Content Director,, Natural Products Insider

Todd Runestad has been writing on nutrition science news since 1997. He is content director for and Natural Products Insider digital magazines. Other incarnations: supplements editor for, Delicious Living!, and Natural Foods Merchandiser. Former editor-in-chief of Functional Ingredients magazine and still covers raw material innovations and ingredient science.

Connect with me here on LinkedIn.


Todd writes about nutrition science news such as this story on mitochondrial nutrients, innovative ingredients such as this story about 12 trendy new ingredient launches from SupplySide West 2023, and is a judge for the NEXTY awards honoring innovation, integrity and inspiration in natural products including his specialty — dietary supplements. He extensively covered the rise and rise and rise and fall of cannabis hemp CBD. He helps produce in-person events at SupplySide West and SupplySide East trade shows and conferences, including the wildly popular Ingredient Idol game show, as well as Natural Products Expo West and Natural Products Expo East and the NBJ Summit. He was a board member for the Hemp Industries Association.

Education / Past Lives

In previous lives Todd was on the other side of nature from natural products — natural history — as managing editor at the Denver Museum of Nature & Science. He's sojourned to Burning Man and Mount Everest. He graduated many moons ago from the State University of New York College at Oneonta.


"There is not a colds-and-flu season. There is a vitamin D-deficiency season."

"There is no such thing as inclement weather. Only improper attire."

Link answers question, "When taking magnesium, should you also take vitamin D3 2,000 IU?"

"Cannabis is nature's most nearly perfect plant."

Subscribe and receive the latest insights on the health and nutrition industry.
Join 37,000+ members. Yes, it's completely free.

You May Also Like