A “Striking” Link Between Vitamin D Levels and Omicron
Low levels are associated with the severity of Omicron and other variants.
Key points
* A low vitamin D level "is surely a primary cause of severe COVID-19" say some researchers.
* Results are equally relevant for Omicron as for previous strains, and likely those still to come.
* Vitamin D affects many organs and the immune system.
* A study is the first to examine existing vitamin levels in people before they contracted COVID. “We found it remarkable, and striking,”
New data reveal an unexpected risk factor for the highly contagious Omicron virus—low levels of vitamin D.
Source: Fernando Zhiminicela / Pixabay
A recent study by Israeli scientists found “striking” differences in the chances of contracting severe COVID-19 illness between individuals with sufficient levels of vitamin D prior to catching the virus and those who did not.
Half the vitamin-deficient people developed severe, life-threatening illness compared to fewer than 10 percent of those who had normal levels. The study is the first to examine existing vitamin levels in people before they contracted COVID. “We found it remarkable, and striking,” said the lead author, “to see the difference in the chances of becoming a severe patient when you are lacking in vitamin D compared to when you’re not.”
The data come from 253 people who were admitted to a hospital between April 7, 2020 and February 4, 2021—a period of time before the highly-infectious Omicron variant appeared. The results, however, are “equally relevant” for Omicron as for previous strains, say the study authors.
Vitamin D is largely synthesized naturally in human skin and requires direct exposure to sunlight (specifically, UV-B). Artificial light, no matter how bright, doesn’t cut it. Given how the pandemic has kept many people primarily indoors for over two years, it is easy to see how a considerable number of individuals might have fallen below the threshold for adequate vitamin levels—which conventionally is at least 20 nanograms per milliliter of blood.
New data, however, indicate that even this is too low. A minimum level of 50 mg/mL is now advised. Levels below his are said to cause weak innate immune responses to common that which cause post-operative infections.
Diet plays a much lesser role in the vitamin’s intake and maintenance. It is soluble in fat rather than water, and found in foods such as fresh fatty fish, mushrooms, egg yolks, full-fat yoghurt, beef liver, and duck. According to Prof. Robin Wright of Victoria, Australia, the quantity of Vitamin D3 is food is quite small.
For most people with inadequate sun exposure "the only practical way of ensuring good levels ... is vitamin D3 supplements," says Prof. Wright. A low vitamin D level "is surely a primary cause pf severe COVID-19" (See his comments after the Chauss et al. reference below).
Source: Sumanley Xulux / Pixabay
Throughout the life span the vitamin regulates the metabolism of calcium, which is crucial for the development and maintenance of healthy bones. It prevents rickets in children and osteoporosis in adults. The latter results in brittle bones and, correspondingly, otherwise avoidable fractures. Muscle and bone weakness also render individuals prone to falls. Its active metabolite acts as a hormone that targets the kidney and other organs, giving it a role in heart disease, diabetes, cancer, and immune cells (this last is a complex topic beyond the scope of this column).
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Research published in The Lancet and compiled before the emergence of COVID varieties found that, compared to dummy drugs, adequate vitamin D also reduced the risk of contracting other respiratory infections.
The Israeli researchers cautioned that vitamin D was only “one piece of the complex puzzle” underlying cases of severe COVID-19. It alone doesn’t constitute proof of cause. Yet it does seem to serve as a useful marker to flag individuals who may go on to develop serious illness.
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References
Pre-infection 25-hydroxyvitamin D3 levels and association with severity of COVID-19 illness. February 3, 2022. PLOS One. doi.org
Vitamin D, an essential nutrient with versatile functions in nearly all organs. International Journal of Vitamin and Nutritional Research 10.1024/0300-9831/a000151.
Vitamin D supplementation to prevent acute respiratory infections: a systematic review and meta-analysis of aggregate data from randomised controlled trials. The Lancet: Diabetes and Endocrinology. doi.org
Association Between Preoperative 25-Hydroxyvitamin D Level and Hospital-Acquired Infections Following Roux-en-Y Gastric Bypass Surgery
S. A. Quraishi, et al. JAMA Surgery Vol. 149(2) Pages 112-118. DOI: 10.1001/jamasurg.2013.3176
Chauss, D. et al. Autocrine vitamin D signaling switches off pro-inflammatory programs of TH1 cells. Nature Immunol 23, 62–74 (2022). doi.org. According to Prof. Wright, "Th1 lymphocytes of hospitalised COVID-19 patients are continually hyper-inflammatory due to insufficient 25-hydroxyvitamin D - never switching from their pro-inflammatory startup program to their anti-inflammatory shutdown program ... This is surely a primary cause of severe COVID-19,"
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