Vitamins are organic substances essential in the metabolic processes that take place in the nutrition of living beings. Do not bring energy, since it is not used as fuel, but without them the body is unable to take the constructive elements and energy provided by food. Usually used inside cells as precursors of coenzymes, from which are prepared thousands of enzymes that regulates chemical reactions of living cells.
The vitamins must be supplied through diet because the human body can not synthesize them. One exception is vitamin D, which can be formed in the skin with sun exposure, and vitamins A, B1, B12 and folic acid, formed in small amounts in the intestinal flora.
With a balanced diet and plenty of fresh, natural products, we will have all the necessary vitamins and will not need any additional input in the form of supplements or herbal pharmacy. An increase of biological needs requires an increase in these substances, as in certain stages of childhood, pregnancy, lactation and in old age. Consumption of snuff, alcohol or drugs in general causes a greater expenditure of some vitamins, so in these cases you may need nutritional supplements. We must bear in mind that most synthetic vitamins are no substitute for the organic, i.e. those contained in food or extracted from natural products (yeast, wheat germ, etc.). Although the molecules of the synthetic vitamins have the same structural elements that organic, in many cases have the same spatial configuration, thus changing its properties?
There are two types of vitamins: fat soluble (A, D, E, and K), which dissolve in fats and oils and water soluble (C and B complex), which dissolve in water. Let's see the general characteristics of each group and the main features of the most important vitamins. It includes tables with foods rich in each vitamin and the amount needed per day according to the recommended dietary allowance (RDA) National Research Council of the United States (NRC, USA). We have also included a table of minimum daily requirements of vitamins important at different stages and life situations, according to the same recommendations. In those cases where the input can be critical, we must ensure that our diet includes them to avoid deficiencies.