Vitamin D, also known as cholecalciferol, is a steroidal prohormone considered an essential fat-soluble micronutrient, that is, it has the ability to dissolve in fat and, which in combination with parathyroid hormone (PTH), acts on bone maintenance. Its main forms found in nature are vitamin D2 and vitamin D3, which can be acquired in food.

In addition, it is believed that the active form of cholecalciferol has immunomodulatory effects (acts on the immune system by increasing the organic response against certain microorganisms) on the cells of the immune system, especially T lymphocytes. On the other hand, when there is a deficiency of cholecalciferol in the body, we can associate it with a greater risk of developing chronic diseases, such as cardiovascular problems, tumors and immunological and infectious diseases.

What does vitamin D do?

As the main function of vitamin D, we can mention its action in increasing intestinal absorption of calcium, participating in stimulating the active transport of this ion in enterocytes (a type of epithelial cell in the superficial layer of the small intestine and large intestine). As stated at the beginning, cholecalciferol also acts on the mobilization of calcium in the presence of PTH. Recently, there was some evidence that cholecalciferol replacement or ingestion could have a positive effect on immune system cells (T lymphocytes), which pointed to beneficial effects of vitamin D supplementation in preventing the development of autoimmune diseases. However, these studies were small and uncontrolled.

Is our body able to produce vitamin D?

As long as there is exposure to sunlight, our bodies are fully capable of producing vitamin D3, which can also be found in foods such as milk, eggs and some species of fish. Vitamin D2, on the other hand, because it is of vegetable origin, can be found in wild mushrooms, for example. However, both after being metabolized in the body, they provide the same benefits and functions.

And how to replace vitamin D by the sun?

For our body to be able to produce vitamin D through exposure to the sun, UVB radiation needs to have direct contact with our skin, especially regions such as the arms and face. With only a few hours of exposure, we have already achieved the production and replacement of vitamin D. This reaction involves the participation of substances present in the skin that transport cholecalciferol to the liver, converted into 25-hydroxyvitamin D3 (calcidiol).

How much vitamin D do we need to eat each day?

Whether through its natural production by the sun, by eating foods composed of cholecalciferol, or even by supplementing vitamin D, the daily vitamin D recommendation can change according to the age of each person, ranging from 400 IU to 20 mcg. In fact, nutritionists have already stressed that the vitamin should be consumed only within the recommended amounts by age group and supplemented according to need.

Does vitamin D eliminate the risk of getting Coronavirus?

Since the beginning of the pandemic, we have known the vitamin as a strong ally in fighting the coronavirus. As much as it plays a very important role in strengthening our immune system, the vitamin alone does not work by eliminating the risk of contracting the disease. The observed evidence of the positive effects of vitamin D against Covid-19, were more based on people who, at that time, had a certain degree of vitamin deficiency, thus evidencing its benefits in increasing the immune system. We know that when there is insufficient cholecalciferol, our body is more favorable to the development of diseases, including immunological and infectious ones.

After the disclosure of the alleged indication of the vitamin, the Brazilian Society of Endocrinology and Metabology (SBEM), published in a note, its repudiation regarding the use of high doses of cholecalciferol supplementation (vitamin D3) “as a strategy to optimize immunity against the new coronavirus (COVID-19) “. Therefore, avoid the indiscriminate use of vitamin supplementation.

What about vitamin D deficiency or insufficiency?

When we do not produce or ingest a certain amount of the vitamin, insufficient cholecalciferol will be the result. This deficiency will cause bone demineralization, which manifests itself as rickets in children and osteomalacia in adults.

What are the symptoms of vitamin D deficiency?

With the lack of vitamin D, we may see some symptoms. Among them, an increase in infectious diseases, since one of the vitamin’s roles is precisely in helping to strengthen the immune system, which will be able to fight viruses and bacteria that cause diseases. Another symptom is extreme tiredness frequently. Case studies have shown that very low blood levels of cholecalciferol can cause recurrent fatigue. On the other hand, elderly people may experience pain in the bones, back and bone loss, since the vitamin has a fundamental role in calcium absorption and bone metabolism.


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