After studying global data from the novel coronavirus (COVID-19) pandemic, researchers have discovered a strong correlation between severe vitamin D deficiency [based on blood levels] and mortality rates.
Led by Northwestern University, the research team conducted a statistical analysis of data from hospitals and clinics across China, France, Germany, Italy, Iran, South Korea, Spain, Switzerland, the United Kingdom (UK) and the United States.
The researchers noted that patients from countries with high COVID-19 mortality rates, such as Italy, Spain and the UK, had lower levels of vitamin D compared to patients in countries that were not as severely affected.
Our bodies have two source of vitamin D. Our skin can make it if given sufficient exposure to sunlight, or we can ingest it. Many folks don’t swallow and/or absorb enough of it, or don’t get enough sun exposure.
I’ve never been to Europe and readily confess I don’t know much about it. I figured the UK doesn’t get much sunlight, but Spain and Italy do (at least southern Italy). Maybe the heavy air pollution in northern Italy—e.g., Lombardi—blocks out the sun.
The researchers say that vitamin D keeps the immune system from over-reacting to the virus infection. A hyperactive immune system response causes widespread inflammation, which in turn damages various body tissues, leading to severe illness and sometimes death. This is the “cytokine storm” you may have heard about. That’s the theory anyway.
I never knew vitamin D was involved in the immune system, or if I did, I forgot. Like most physicians, my interest in vitamin D relates to calcium metabolism and bone health/fracture prevention.
Professor Backman is quoted in the article:
It is hard to say which dose [of vitamin D supplement] is most beneficial for COVID-19,” Backman said. “However, it is clear that vitamin D deficiency is harmful, and it can be easily addressed with appropriate supplementation. This might be another key to helping protect vulnerable populations, such as African-American and elderly patients, who have a prevalence of vitamin D deficiency.
A few days ago, CNN reported that black people are four times more likely to die from COVID-19 than are whites. Here in the U.S., we’ve seen disproportionately high fatalities among blacks living in Chicago, New Orleans, and Milwaukee County, Milwaukee. I’m not the first to wonder if vitamin D deficiency is a contributing factor. I mentioned earlier that our skin makes vitamin D when exposed to sufficient sunlight. But that process is less efficient in darker skin. And folks at more northern latitudes tend to get less sun exposure, particularly in winter. (Lack of sunlight shouldn’t be a problem in New Orleans). We’ve know for years that U.S. blacks have “sub-optimal” vitamin D blood levels. Click for even more reading on this issue if you’re crazy; it’s complicated. Despite low blood levels of 25-hydroxyvitamin D, blacks are not prone to thin-bone osteoporotic fractures like whites and east asians. Some experts suggest that higher rates of diabetes and hypertension in U.S. blacks is related to low vitamin D levels.
What we don’t know is:
- If you have COVID-19 and try to augment your vitamin D level with a supplement, will you have a better outcome?
- If you are deficient in vitamin D now but take measures to raise your blood level (via food or supplementation), will you be less likely to contract COVID-19 and able to avoid serious illness if you do get sick?
- Would the answers to the first two questions depend on whether you have black, brown, white, pink, or polka-dotted skin?
Hey, doc. Tell me something concrete I can do now to improve my odds of surviving this pandemic!
If you’re black of otherwise dark-skinned, I don’t know what to tell you.
If you qualify as a vulnerable person, why not ask your doctor to order a vitamin D blood level (called 25-OH-vitamin D)? If that’s not possible, ask your doc if 1,000 units of vitamin D3/day (cholecalciferol) by mouth is a good idea.
Steve Parker, M.D.
PS: About a week ago I ran across a study finding that pre-sickness use of vitamin D supplements was linked to worse outcomes in COVID-19. I tried to find it a few days later but couldn’t. I’m sorry if this perplexes you. Welcome to the scientific literature and nature of medical practice.