At the beginning of May, a pair of studies emerged suggesting people who are deficient in vitamin D are more likely to experience serious health complications if infected with COVID-19.
Sales of the micronutrient soared as a scared public tried to gain any advantage they could over the virus.
Unfortunately, one researcher at the University of Alberta said the latest revelations are just another fallacy that has helped build vitamin D into a multibillion-dollar wonder vitamin 30 years in the making.
The researcher is pediatrics professor Todd Alexander.
In the 1980s and ’90s, studies emerged that found a role for vitamin D in immune function.
This led to a deluge of clinical studies finding reduced vitamin D levels in people affected by a host of diseases including asthma, cancer, diabetes, and multiple sclerosis.
The problem with that is that associative data doesn’t necessarily imply causation—and the COVID-19 findings follow the same fallacy.
The researcher noted the results of proper randomized controlled studies on vitamin D supplementation are only now emerging to show that it doesn’t prevent people from getting ailments such as cancer and asthma.
That’s not to say vitamin D isn’t important. At the beginning of the 20th century, a deficiency of vitamin D was found to cause rickets, a childhood bone disease resulting in misshapen and poorly grown children.
Examination of hospital records from that time revealed that up to 50% of the population of industrializing nations were affected. In response, Canada and other countries began fortifying foods with vitamin D, such as milk products.
This greatly decreased the prevalence of nutritional rickets in Canadian children to current levels of about three cases per 100,000.
Studies showed the primary effect of vitamin D—which occurs naturally in fatty fish, liver, and eggs, as well as when sunlight is absorbed through the skin—is to enhance absorption of calcium from the intestine.
The researcher further explained that the form of vitamin D used in supplements requires activation in the kidney and liver. Too much vitamin D can cause problems.
The calcium created by large doses of supplementation, certainly greater than 2,000 IUs per day, cannot be deposited into bones and is lost in the urine.
This increased amount of calcium in the urine is often crystallized forming kidney stones that are painful to pass and can cause kidney disease.
The researcher said the number of people who are actually deficient in vitamin D is quite low, and that 600 IUs is sufficient to maintain healthy bones in most adolescents and adults.
For older adults and those at risk of osteoporosis, this is likely a little higher, 800 IUs.
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