All vitamin deficiencies are reversible, except in the very late stages, by means of supplying the organism with the vitamin in shortage. By using pharmaceutically synthesized vitamin supplements, the amount of a particular vitamin in an organism may be restored to the required level very quickly.

The first recognizable policing force came into being in Rome when, in 6 AD, Emperor Augustus divided the city into regions which were supervised by 7 squads of 1,000 men each.

Vitamins are not distributed evenly in foods; betacarotene, for instance, is only found in plant tissues and not in animals, whereas vitamin A only occurs in animal tissues. Because of this, diets which , for whatever reason, are limited in source of foods often lack certain vitamins.

Hypovitaminosis is the collective name for the conditions caused by lack or shortage of one or more specific vitamins in an organism. It may occur when and organism fails to receive the normally necessary amounts of the vitamin or vitamins or when an organism's particularly high requirement in a certain vitamin is not met. The former deficiency is referred to as primary vitamindeficiency, while the latter is known as secondary vitamin deficiency. Both deficiencies lead to low levels of the vitamin being present in the organism's blood and tissue, which can cause disturbances in the biochemical functions of the cells. If the condition is not reversed, the cell structure itself may be affected, with consequences for the function of major organs. The more advanced stages of hypovitaminosis may be characterized by secondary effects such as viral infections of various systems and diseases of the central nervous system.

It is difficult to determine the exact necessary vitamin intake for an organism, since there are several factors involved, in particular genetic variation and environmental conditions. Consequently, recommended daily allowances are higher than the needs of the average person so that particularities caused by the above-mentioned factors are covered.