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French Agency for Food, Environmental and Occupational Health & Safety

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Updated on 14/06/2019

What are vitamins?

Presentation

Keywords : Vitamins, Nutrition, Food composition

Vitamins are substances which have no energy value but which are vital for the body since they are needed for a great many of its physiological processes. Aside from vitamins K and D, the human body cannot synthetise vitamins. Because of this we need to get them though our diet so that our bodies can function correctly.

What do vitamins do?

Vitamins are involved in many biological functions, including construction of the body (growth, skeletal development, etc) and its functioning and maintenance (transformation and use of micro-nutrients, sight, blood clotting, the muscular, nervous and immune systems, production of DNA, etc.).

The body needs a balanced and varied diet to cover its needs along with an adequate supply of vitamins in order to prevent many pathologies (diseases associated with ageing, cardiovascular diseases, and cancer).

An excessive intake of vitamins does not improve the performance of a normally functioning body. In fact, their over-consumption can lead to medium- or long-term toxic effects. Conversely, an inadequate intake can lead to deficiencies or even malnutrition as well as clinical and/or pathological disorders.

 

Two main groups of vitamins

Thirteen types of vitamins have been defined and classified into two groups:

  • Liposoluble vitamins (i.e. which can dissolve in fat): vitamins A, D, E, and K. These vitamins are stored in adipose tissue (vitamines D and E) and to a significant degree in the liver (vitamin A). The fact that they can build up in the organism means there is a potential risk of toxicity if intake is too high;
  • Hydrosoluble vitamins (i.e. which can dissolve in water) include the B group of vitamins (B1, B2, B3 or PP, B5, B6, B8, B9 and B12) and vitamin C. These vitamins can also be stored by the body, but there is less of a risk of overdosing as they are eliminated through the urine.