By now, we have several studies showing a strong correlation between vitamin D deficiency and the (a) Covid-19 infection rate, and (b) Covid-19 complications. Here's a study from Boston University and Quest Diagnostics. Here's one from the University of Chicago. Here's one from the University of Birmingham (UK). Sample finding:
At the same time, we have skeptics like Leonid Schneider, who can't believe a major factor in Covid-19 could be something that simple. He ridicules vitamin D because it's associated with "natural cures", since Schneider despises placebos. He doesn't understand that placebo and nocebo are much more important than he imagines; that a major way chemotherapy works is as a more convincing placebo. (For people who don't believe simple cures work, medicine has to cost them.)
If he's proven wrong, he'll find excuses. And if he did not, he will not be able to pay for the damage of these beliefs.
Now, the reason so many are deficient is because the way our society is organized, an individual can't reasonably fix it.
You make vitamin D if your skin is exposed to the sun, but not just any kind of sun. Ultraviolet light comes in three bands: UVA, UVB, and UVC. To make vitamin D, you need UVB, which is absorbed by the ozone layer. Only about 5% get through, and then only when the sun is high. In winter, in Europe and the US, no UVB reaches the ground. In summer, you have to be out at peak sun. You have to not use sunscreen, at the exact time of day when parents, newspapers and doctors are scaring you about skin cancer. With Daylight Saving Time, this peak might be 11 am to 3 pm; use this great sun calculator. The sun altitude needs to be at least 50 degrees (correction: or not!). If it's 45, you can still make some vitamin D, but the effectiveness drops precipitously (correction: or not!). In spring and autumn, the sun is only high enough at mid-day.
So you have an office job in a high-rise downtown. It's summer, and at 1 pm you want to tan for 30 minutes. You undress to your underpants, and go where? Put down a towel on the sidewalk?
Then there's weight and skin. The heavier you are, the more vitamin D you need for the same blood concentration. The darker you are, the more sun you need to make the same amount of vitamin D. The darkest-skinned people in northern latitudes can likely never make enough with just sun exposure. Now imagine you're dark-skinned and obese.
So then we have supplementation. Here, many doctors graduate from medical school and stop updating their knowledge. They're stuck 10 or 20 years ago, when people thought 400 IU was a good daily dose of vitamin D3. This is completely ineffective. Therapeutic doses that help patients with Covid are 10,000 - 25,000 IU per day. In my experience with supplementation and testing, to raise the blood level from deficiency to optimum (60 - 80 µg/L), I was taking 7,000 IU per day for several months. To maintain an optimum level, I used 3,000 - 5,000 IU per day without additional sun exposure.
Dr. Holick, who is a long-time champion of vitamin D, and co-author of one of the above studies, thinks the belief in vitamin D toxicity is false, and there is no danger. Still, if you get vitamin D from the sun, you will not overshoot optimum levels. The body will stop making it. But if you supplement, you can overshoot. If you get a blood test, lots of doctors will warn you to immediately stop supplementation. They may be wrong, they may be right, but the safe thing is to get tested.
So then there's testing. In countries with socialized health care, you're at the mercy of your physician, who may have arbitrary opinions and will convince you of them. In the US, insurance companies don't (yet?) see the value and prefer not to pay. You can order it online and pay yourself. But then you have to know which test to take. Do you recognize the right test from the search I linked? You have to know how to interpret it. Can you do that? And it costs $60 - $100.
Your grandma doesn't know how to do this. She has to see a doctor, and that's another $100. And she has to do this every month – if we believe it's truly important she does not overshoot optimum levels.
No wonder so many are deficient. And it seems they have the highest rate of infections and complications from Covid-19.
Actual measured deficiencies
I was pointed to this clinical study by Valens in Slovenia, which took place in January to March 2019. The study found:
- 21% of the population had levels below 12 µg/L
- 66% had levels below 20 µg/L
- 90% had levels below 30 µg/L
These numbers are catastrophic. What's even more concerning is that people consider 30 µg/L "optimal". The optimal range is not 30 – 90! According to Stasha Gominak, it is 60 – 80, and this is consistent with the Covid-19 studies.