The simple definition of vitamins above should enable an unambiguous and doubt-free classification. Even nowadays however, active ingredients are still classified as vitamins even though they do not fulfil the definition of a vitamin, partly due to ignorance of their pharmacological characteristics, but also as a result of strategic marketing considerations. These so-called vitaminoids possess characteristics that are similar to vitamins and are contained in foodstuffs. In contract to vitamins however, they are also produced by the body. Some of these vitaminoids have been listed as examples in the following list:
- L-carnitine and combined carnitine (acetyl-carnitine)
- Ubichinon (coenzyme Q)
Provitamins however are still ineffective preliminary stages of vitamins and must first be transformed into vitamins in the organism for them to be of use to the body. Some examples of provitamins are the following compounds:
- Beta-carotene (provitamin A)
- Ergosterol (provitamin D2)
Why should the vitamin content of foodstuffs be analytically monitored?
Vitamins have an essential function in nutrition and as a result are added in a targeted manner during the foodstuff manufacturing and processing stages for technological, nutritional and physiological reasons, alongside the naturally occurring vitamins that are already present.
In the event of insufficient intake of vitamins, hypovitaminosis can occur (deficiencies such as scurvy occur with a lack of vitamin C or rickets with a lack of vitamin D), and in later stages avitaminosis (severe forms of deficiencies) appears that can lead to death.
But it is not only hypovitaminosis that is critical. A too high content, particularly of the fat-soluble vitamins, can also cause problems. After being absorbed from food, vitamins are stored in the fatty tissue of the body for a long period of time, that can lead to toxic effects (hypervitaminosis). Too high doses of soluble vitamins are less problematic because they are excreted from the body again quickly.