What relationship do calcitriol, cholecalciferol and vitamin D have?

Vitamin D is a substance essential for our body. We can get it from food or we can synthesize it from cholesterol and the help of sun radiation. Currently we tend to think of vitamin D as a hormoneas it does not fit the usual definition of a vitamin.

Rickets and osteomalacia are the two best-known diseases caused by vitamin D deficiency, although it is also very important in other diseases, for example osteoporosis.

In northern countries it is common to recommend vitamin D supplements during the winter, when the solar intensity is very low, but sometimes there is confusion between the names used, especially between calcitriol Y cholecalciferol. Let's see what exactly each one is.


The term vitamin D is used to collectively refer to a group of substances that share a similar chemical structure, all of which are secosteroids. The forma biologically active vitamin D It is the substance known as calcitriol.

Calcitriol can be synthesized in the kidneys from two metabolites:

  • cholecalciferol or vitamin D3. Produced by animals and plants. The human species produces it in the skin from cholesterol in a reaction involving solar radiation.
  • ergocalciferol or vitamin Dtwo. Produced by fungi.

The ergocalciferol and cholecalciferol are absorbable in the intestine, calcitriol does not, its only source is internal synthesis. Therefore, to meet our vitamin D needs, we need ergocalciferol or cholecalferol, which we can obtain from the diet or from internal synthesis in our own body.


Cholecalciferol or vitamin D3 It is the most widely used absorbable form of vitamin D. nutritional supplements Y fortified foods. Ergocalciferol is believed to be less effective and is used less. Cholecalciferol is also the most widely used as drug in medicines to treat nutritional deficiencies; It is also used in pharmacotherapy for diseases related to calcium metabolism, such as osteoporosis.

How dietary sources of vitamin D3 highlight the fatty fish. Oils made from these fish, such as cod liver oil, are used as natural vitamin D supplements, either the oil directly or presented in pearls or capsules. It is also found in appreciable quantities in most meats, fish, eggs, cereals and grainsespecially integral, and beer yeast.

Although it exists in a considerable variety of foods, the main natural source of vitamin D3 for our body is solar exposition. It can be difficult to get the necessary amount if sun exposure is low, periods in which supplementation is usually recommended.

The UK National Health Service, for example, recommends widespread supplementation with 10 µg cholecalciferol during the fall and winter (1 µg cholecalciferol = 10 IU).

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