Vitamin D is sometimes called the “sunshine vitamin” because it’s produced in your skin in response to direct sunlight exposure.
It’s a fat soluble vitamin in a family of compounds that includes vitamins D-1, D-2, and D-3.
Using SPF creams restricts your bodies ability to absorb vitamin D.
You can also obtain it through certain foods (eggs, salmon, sardines, red meat, liver, mushrooms) and supplements, to ensure you have adequate levels of vitamin D in your blood.
Vitamin D has several important functions, perhaps the most vital are regulating the absorption of calcium and phosphorus , and facilitating immune system function.
Getting a sufficient amount of vitamin D is important for normal growth and development of bones and teeth, as well as improved resistance against certain diseases.
A growing number of studies also point to vitamin D deficiency as a risk factor for heart attacks, heart failure, peripheral arterial disease, strokes, and the conditions associated with cardiovascular disease, such as high blood pressure and diabetes.
It has long been known that vitamin D acts as a vasodilator and reduces hypertension (high blood pressure) as well as reducing inflammation.
As it is accumulative, if your body doesn’t get enough vitamin D in the summer, you will have depleted levels through the darker winter months (particularly in the northern hemisphere and/or if you have skin with darker pigment which absorbs less UVB rays from the sun) and be more susceptible to infections and viruses, which is why it is very important to supplement throughout the winter....particularly this winter!
The definition of vitamin D deficiency in the UK is 10 ng/dl in the blood, but this is very, very low.
Good bone health requires 40 ng/dl and there is good evidence to support 40-60 ng/dl being optimal for overall health and optimum immune system function.
Higher vitamin D levels are associated with significantly better COVID-19 outcomes, so be sure you are not deficient.
Researchers recently compared people with asymptomatic COVID-19 infections to people with severe infections:
97% of people in the severe group had vitamin D deficiency! (average level of 14 ng/dl) vs. 33% percent in the asymptomatic group (28 ng/dl—which, you will note from my comments above I would still consider deficient).
People with low vitamin D also had higher levels of inflammatory markers like ferritin, tumor necrosis factor-alpha, and interleukin-6.
The fatality rate was seven times higher in the low vitamin D group (21% vs. 3%)
This is the 15th observational study investigating the connection between vitamin D and COVID-19.
Of these 15 studies, 12 found an inverse association between vitamin D levels and the risk of severe COVID-19 infection (meaning people with lower vitamin D had a higher risk of severe infection).
Of the three trials that didn’t find this association, two had very long intervals (sometimes over a year) between measuring 25 (OH)D levels in the participants’ blood and when they contracted COVID-19. This makes the findings less reliable.
Once it enters the body from the skin or through your diet it goes to the liver to be converted to 25(OH) Vitamin D.
Every cell in your body has a vitamin D receptor, and it regulates anti-body activity and immune function.
Some of this amazing power has been known as long ago as 1849 when cod liver oil was used to help beat Tuberculosis.
In 2006 (Morten, Adams and Lu) it was discovered that macrophages activate vitamin D which tells cells to produce a protein called Cathelicidin, which specifically kills infectious agents like Tuberculosis and Coronavirus.
The seasonal stimulus for flu can be attributed to a greater degree to when blood levels of vitamin D are at their lowest, and conversely respiratory tract infections are at their highest.
Vitamin D regulates gene expression (over 80 of them in fact) those inc things like
Supplementation with 10,000 international units of vitamin D per day were shown to regulate over 1,000 genes in a positive way.
Vitamin D helps adaptive immunity protection for COVID-19....but also helps prevent catching it in the first place through interaction with the angiotensin receptors which is how COVID-19 can access the body.
Another study on 160,000 people has shown that being vitamin D sufficient (60 ng/dl v 20 ng/dl) reduces covid risk by 54%.
How do you know if you are Vitamin D deficient?
Answer yes to two of these questions and the answer is "probably".
Answer yes to 3 or more and the answer is "definitely!".
Do you live in the Northern Hemisphere?
Do you have dark skin pigmentation?
Do you use suncream, or a moisturiser containing SPF?
Do you spend most of your day working indoors or fully-clothed?
Are you a vegan?
Alternatively you can always buy a finger-prick test kit like this one here from Forth Life.
For dramatically reduced heart-disease and COVID-19 risk, I would recommend that you supplement with at least 4,000 iu of vitamin D per day.
You can buy a great source of it here. I would highly recommend this as a stocking-filler for Nan or Grandad! It might mean they are around for next Christmas too!
NB. (I don't receive any payment for this or any other supplement recommendation).
For optimal health or if you have already suffered heart disease, supplement up to 10,000 iu per day.
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