Vitamins are micronutrients, needed in very low amount to satisfy the metabolic needs of the body. Some of them can be auto-produced, but most of them should be received from diet. Vitamins are involved in many reactions and metabolic processes and contribute to the development and correct operation of tissues and organs; moreover, some of them, are antioxidant. In particular, vitamins are fundamental coenzymes in glycolysis and Krebs cycle, they are important for the good health of bones, teeth, nervous system and eyes.

Vitamins shortage can lead to consequences of different degrees of concern, until the development of diseases, so when the vitamins intake is not enough to satisfy the organism needs, it is useful to supplement them through food supplements.

A vitamin supplement is useful to sustain convalescence, when the immune system is weak and the lack of appetite leads to a lower nutrients intake; it is useful in case of asthenia, typical at the season changes, or in case of stressful moments and intestinal disorders or antibiotics treatments. Moreover, the vitamin supplementation is useful when the nutrient intake is not enough, as in consequence of lack of appetite, e.g. in the elderlies, vegan or vegetarian diets and in all the cases of bad diet habits. In the end, vitamins supplementation is useful in case of chronic treatments with drugs, which counteract the absorption of vitamins or determine a higher vitamin consumption at metabolic level, such as birth control pills, diabetes and anti-inflammatory drugs and other.

A specific application of a multi-vitamin dietary supplement is hyperhomocysteinemia, a medical condition characterized by an abnormally high level of homocysteine in the blood, caused by genetic or dietary problems; hyperhomocysteinemia is caused by B12, B6 and B9 shortages, and it is correlated to cardiac and neurological diseases.

Vitamin B9 (folic acid) and B12 are required for the conversion of homocysteine to methionine. It is clear the correlation between the dietary supplementation of group B vitamins and the reduction of plasmatic levels of homocysteine.