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Aristo Glossary

Medical terms explained in simple English.


The remedy of choice for systemic vitamin D deficiency

Colecalciferol is a precursor of the active vitamin D, which is involved in various metabolic processes. It plays a particularly important role in the formation of bones as well as in the functioning of muscles and the immune system. A large part of the population of Central and Northern Europe is affected by an undersupply of vitamin D. By taking Colecalciferol, this can be remedied effectively and with few side effects.

What is Colecalciferol?

Colecalciferol is also known as vitamin D3. Strictly speaking, the term “vitamin” does not apply. Colecalciferol, for example, is a so-called secosteroid that assumes the function of a prohormone in the body. From this preliminary stage, the physiologically active hormone calcitriol is formed in several intermediate steps.

Colecalciferol is essential for the human body. The need is largely covered by the skin. Under the influence of UV-B radiation, Colecalciferol is formed from 7-dehydrocholesterol, a precursor of cholesterol. In addition, vitamin D3 is partly found in food, especially in fatty sea fish. It is also present in traces of other animal fats and in some vegetable foods.

What role does Colecalciferol play for health?

Colecalciferol is involved in numerous metabolic processes. Colecalciferol and the active vitamin D derived from it are of central importance, especially for bone health. It promotes the absorption of calcium from the intestines and kidneys and supports the formation of the bone matrix. A prolonged vitamin D deficiency can therefore contribute to the development of bone softening (osteomalacia) and increased bone fragility (osteoporosis). In infants and toddlers, the undersupply can cause rickets. This disease causes malformations of the skeleton.

A sufficient supply of vitamin D, on the other hand, has a positive effect on bone metabolism as well as on the formation and regeneration of muscles. Vitamin D also has a positive influence on the immune system. In addition, numerous studies discuss a protective effect against chronic diseases, diabetes mellitus type 2, certain types of cancer, autoimmune and cardiovascular diseases.

How does a vitamin D3 deficiency develop?

Since Colecalciferol is only present in relatively small quantities in food, around 80 to 90 percent of the requirement is covered by the body's own production. However, this can only be achieved if the skin is exposed to the sun for a sufficiently long time. In Germany, sufficient Colecalciferol can only be produced between March and October, in the autumn and winter months the UV-B radiation is too low for this purpose. The body can store vitamin D3 so that it is theoretically possible to bridge the cold season with the reserves stored in summer. However, the body's own production during the summer months depends on a variety of factors. These include:

  • Sun protection measures: In order to prevent light-induced skin damage and skin cancer, it is generally recommended to protect the skin with sunscreen and clothing in summer. Due to these measures, which are basically reasonable and recommended by many dermatologists, the body can produce less Colecalciferol itself.
  • Staying indoors: More and more people today work indoors, also leisure activities are increasingly taking place indoors. Therefore, the exposure to UV light in summer is often not sufficient to cover the total demand for the whole year.
  • Age: With increasing age the skin often produces less Colecalciferol. This correlation can be observed particularly in women.
  • Further risk groups: People with darker skin colour living in Central or Northern Europe have a higher risk of developing vitamin D deficiency. The same applies to infants, people in need of care and those wearing veils.

What symptoms can occur due to a lack of Colecalciferol?

Serious vitamin D3 deficiency is relatively rare. However, a considerable part of the population has an undersupply. Around 60 percent of Germans are not optimally supplied with vitamin D according to international criteria. A long-term undersupply can be reflected in the following symptoms, among others:

  • increased susceptibility to infection
  • fatigue, depressive mood
  • hair loss
  • muscular weakness
  • bone and muscle pain

How can the vitamin D reservoir be replenished?

Low vitamin D stores can usually not be replenished by food alone. Those who are rarely exposed to direct sunlight or belong to one of the risk groups mentioned above can effectively balance their vitamin D levels with a suitable preparation. It can often make sense to take Colecalciferol already in the summer months to prevent a deficiency during the cold season.

The recommended daily requirement of Colecalciferol is based on age as well as on special circumstances in life such as pregnancy and breastfeeding. According to the German Nutrition Society, in case of a lack of endogenous synthesis, additional vitamin D should be supplied via the skin in the following amounts:

  • Infants (0-12 months): 10 µg*/day
  • Children (1 to under 15 years): 20 µg/day
  • Adolescents and adults (15 to under 65 years): 20 µg/day
  • Adults (65 years and older): 20 µg/day
  • Pregnant women and nursing mothers: 20 µg/day

*1 µg = 40 International Units (IU); 1 IU = 0,025 µg

Is it possible to overdose Colecalciferol?

The additional intake of Colecalciferol should be based on the recommended daily intake. In the case of certain disease patterns and a serious deficiency, higher doses may be used on the advice of a doctor. If high-dose preparations are taken over a longer period of time, the vitamin D status in the blood should be checked regularly. This is because the body cannot simply excrete excess Colecalciferol. If too much vitamin D3 is taken over a long period of time, this can be accompanied by excessively high calcium levels in the blood, which can lead to calcification and damage to the kidneys and heart. Therefore, when taking Colecalciferol you should always keep an eye on the correct dosage and, if necessary, check this by blood tests.

Colecalciferol to remedy a vitamin D deficiency

Preparations containing Colecalciferol are the means of choice for the prevention of vitamin D deficiency or to remedy a symptomatic vitamin D deficiency if adequate sun exposure cannot be guaranteed during the summer months. Higher doses of vitamin D can only be used under medical supervision.


1 Rabenberg, Martina u. Gert B. M. Mensink (2016): Vitamin-D-Status in Deutschland. Journal of Health Monitoring 1(2):36–42. DOI 10.17886/RKI-GBE-2016-036. Robert Koch-Institut, Berlin. (Online:
2 ebd.

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