What is Vitamin D?
Vitamin D (also referred to as “calciferol”) is a fat-soluble vitamin that is naturally present in a few foods, added to others, and available as a dietary supplement. It is also produced endogenously when ultraviolet (UV) rays from sunlight strike the skin and trigger vitamin D synthesis. Then, Vitamin D3 is produced in the skin through the action of UVB radiation reaching 7-dehydrocholesterol in the skin, followed by a thermal reaction. That vitamin D3 or oral vitamin D is converted to 25(OH)D in the liver and then to the hormonal metabolite, in the kidneys or other organs as needed.
The Role of Vitamin D
Optimal vitamin D intake reduces cellular growth (which promotes cancer), protects against respiratory infections and improves cell differentiation (which puts cells into an anti-cancer state). That makes vitamin D one of the most potent cancer inhibitors — and explains why vitamin D deficiency has been linked to colon, prostate, breast, and ovarian cancer and why optimal levels could reduce the risk of those types of cancer.
Some of the other roles of Vitamin D are such as:
- Reducing the risk of common cold
- Reduce risk of acute respiratory tract infections
- Reducing risk of viral infections
- Enhance cellular innate immunity
- Enhance expression of genes related to antioxidation
Vitamin D, COVID-19, Respiratory Tract Infections
One study showed 80% of 200 COVID patients at a hospital in Spain were deficient in vitamin D, with men having lower levels than women, and this was also linked to higher inflammatory blood markers which we know lead to an increased risk for chronic disease. There are other clinical examples that show low vitamin D status in those with COVID-19 leads to an increased severity of symptoms and a higher risk of death.
It has been proven that Vitamin D supplementation can reduce the risk of acute respiratory tract infections and that it plays an important role in immune function. Hence, it is important that we pay attention to it during this COVID-19 pandemic that is known to attack the respiratory system. Vitamin D has many mechanisms by which it reduces the risk of microbial infection and death. A recent review regarding the role of vitamin D in reducing the risk of the common cold grouped those mechanisms into three categories: physical barrier, cellular natural immunity, and adaptive immunity. Vitamin D helps maintain tight junctions, gap junctions, and adherens junctions. Some articles have discussed how viruses disturb junction integrity, increasing infection by the virus and other microorganisms.
Furthermore, Vitamin D also enhances cellular immunity, in part by reducing the cytokine storm induced by the innate immune system. The innate immune system generates both pro-inflammatory and anti-inflammatory cytokines in response to viral and bacterial infections, as observed in COVID-19 patients. Administering vitamin D reduces the expression of pro-inflammatory cytokines and increases the expression of anti-inflammatory cytokines by macrophages.
How do you get Vitamin D?
Vitamin D is one of those nutrients that is harder to acquire from food, though not impossible. The best food sources are fish liver oils, such as cod liver oil, wild salmon, mackerel, herring, sardines in oil, and whole eggs. Mushrooms, especially porcini, are a good plant source of vitamin D. However, obtaining sufficient Vitamin D from food requires consuming high amounts. If not so, it might be a good idea to seek out for supplements to make sure that your Vitamin D are at optimal levels. In relation to this, most of us don’t eat enough of these or get outside in the sunshine enough to optimize our levels. Sunlight is the most effective way to get vitamin D up naturally.