Vitamin D and COVID were linked during the early part of the pandemic. But is vitamin D really a cheap and easy panacea for the prevention, treatment or
cure of COVID or has scientific evidence
shown that it is merely a placebo?
At one point in time, Vitamin D was not only seen as the prevention, treatment or cure for COVID, but for everything from heart attack to cancer!
From early in the pandemic, researchers studied people who got COVID and found that those with low levels of vitamin D did worse than those who were not deficient in the vitamin. These unscientific observations ignored the fact that people with low vitamin D levels are more often older and sicker than the general population and will most likely have worse outcomes if they catch COVID.
At this point in time, accumulated results from properly run randomized trials have shown that vitamin D does not help prevent, treat or cure COVID nor is it recommended for the prevention, treatment or cure of several other diseases it was tested for.
Science-based evidence from properly controlled randomized trials is really the only way we can know what works, before millions, if not billions of dollars are spent on a specific treatment. Below are some results of randomized clinical trials (as of November 2022) involving vitamin D with COVID and some other diseases:
Vitamin D plays an essential role in our bodies by absorbing calcium from our intestines, which is absolutely necessary for proper bone strength. Our bodies can only absorb calcium, the primary component of bone, when vitamin D is present. Vitamin D also regulates many other cellular functions in our bodies.
Direct sunlight will convert a chemical in our skin into an active form of vitamin D (calciferol). The use of sunscreen can diminish the effect, but the risk of skin cancer is always present as well.
Unfortunately, vitamin D isn't naturally found in many foods but can be obtained from fortified foods such as milk, fortified cereal, and fatty fish such as salmon, mackerel, and sardines.
For people who do not get enough sun exposure, taking a vitamin D supplement may help improve bone health. Always have a doctor check blood levels of this vitamin first. Too much vitamin D in the form of supplements can be harmful. (See below.)
The recommended daily amount of vitamin D is 400 international units (IU) for children up to age 12 months, 600 IU for people ages 1 to 70 years, and 800 IU for people over 70 years.
Most of the original studies of vitamin D were based on association from observation. For example, people with low vitamin D levels in their blood had higher rates of cancer and heart disease, etc. And, as mentioned above, so did many of those who got COVID. Therefore, it could be intuitive to think that vitamin D deficiency was the cause of these diseases. But, a third common variable was probably at play:
Thus, we have what is known as reverse causation. People who are sick tend to develop a vitamin D deficiency. But a vitamin D deficiency does not make people sick. These vitamin D assumptions prove again why science-based evidence from randomized trials are essential for sifting out truth from observation and false assumptions.
Before taking any vitamin D supplements, it would be prudent to test for actual levels of the vitamin in the blood. Taking too much vitamin D in the form of supplements can be harmful.
Below are some side effects of more than 4,000 IU a day of vitamin D for children aged 9 years and older, adults, and pregnant and breastfeeding women:
Interactions with certain drugs can also possibly affect the way your body processes drugs. Some of these are:
Vitamin D can affect the way your body processes these drugs but some of them can also interfere with vitamin D’s ability to absorb needed calcium. Please see Vitamin D - Mayo Clinic for more information.
Vitamin D helps to promote healthy bones and it does have anti-inflammatory, antioxidant, and neuroprotective properties that support immune health, muscle function, and brain cell activity.
However, the other touted benefits of vitamin D, especially as a prevention, treatment or cure for COVID are doubtful, according to current scientific, evidence-based randomized trials.
Please note: Information from McGill University Office for Science and Society was used with permission.