Vitamin D is universally recognized for its role in protecting bone health. In recent times, however, the beneficial action on the immune system against attacks by viruses and bacteria has also emerged. Today's research confirms this very important property but only as regards vitamin D3, one of the subtypes of vitamin D. So, let's try to better understand the results of this very recent scientific study, which appeared in the journal Frontiers in Immunology thanks to the work of a group of scientists from the Universities of Surrey and Brighton, UK (Durrant et al, Front Immunol, 2022).
Different types of vitamin D
Vitamin D participates in bone metabolism and calcium homeostasis, that is, in the balance of this mineral that is created inside and outside the cell. Not only that, vitamin D is also considered useful in strengthening the defenses against viruses and bacteria. However, we need to clarify a bit as there are different types of vitamin D. In fact, what we call vitamin D is a group of five vitamins, specifically D1, D2, D3, D4 and D5, with the D2 and D3 forms representing the active forms and therefore the subtypes of interest. Vitamin D2 is contained in plants and mushrooms, while the main source of vitamin D3 is the sun. Other sources of vitamin D3 are of animal origin such as cheese and eggs. Generally, vitamins D2 and D3 are assumed to have a similar function. But is it really so?
Only vitamin D3 strengthens the immune system
Researchers from the United Kingdom have thus tried to understand whether vitamins D2 and D3 may have a similar role in their action on the immune system. For this purpose, 355 women were recruited, who were then divided into two groups. The first group was asked to take supplements containing 15 micrograms of vitamin D2 every day for 3 months, the second group 15 micrograms of vitamin D3, in the same way and for the same duration of the first group. The researchers then subjected the volunteers to medical visits and laboratory tests to evaluate the effect of the two vitamins on the immune system. Well, what has emerged is that the two vitamins have a different impact on our defenses. Vitamin D2 showed no effect while the action of vitamin D3 was noteworthy. In fact, vitamin D3 has been shown to act by modulating the immune system, making it more "tolerant", using the same term used by the authors of the study. This fact is essential to avoid an excessive response of the body to real or non-real threats that can lead, in the first case, to reactions such as the cytokine storm with consequences on blood clotting, in the second case to autoimmune diseases. But that's not all, vitamin D3 stimulated the interferon 1 signaling system, a process that plays a key role in the first line of defense against bacteria and viruses.
Therefore, this is proof that vitamin D3 regulates the immune system, avoiding excessive reactions on the one hand, but putting it in the best conditions to cope with the threats given by viruses and bacteria on the other. As mentioned, vitamin D3 is naturally produced by the skin when it is exposed to the sun's rays. If you live in places with a few hours of light or have a life that leads to little outdoors, you can use vitamin D3 supplements, but in this case you must first talk to your doctor. Alternatively, some foods contain vitamin D3 naturally, such as fish, eggs, especially egg yolks, milk and dairy products. You can also find some foods that are added with vitamin D3, such as breakfast cereals and some plant milks.