Vitamins are essential molecules in small quantities, both for the life of animals and for that of plants; they do not provide energy but perform functions of primary importance:
- Development of the growing organism
- Bioregulatory function
- Precursors or coenzymatic constituents
Vitamins can be classified according to their chemical-physical characteristics; the most traditional differentiation is that of solubility (water-soluble vitamins and fat-soluble vitamins), but there is no lack of distinctions on molecular resistance to heat (thermolabile vitamins and thermostable vitamins), on reactivity to light (photosensitive vitamins and photoresist vitamins) etc.
Being micronutrients of great nutritional value, the intake of vitamins SHOULD be constant in order to avoid any form of vitamin deficiency; however, their intake with food (and sometimes also their metabolic demand - see ascorbic acid [protective against infections] in the winter), varies according to the season. It is also worth remembering that, ignoring the recommended rations for taking vitamins, increases the chances of running into a deficit or (in the case of supplementation or pharmacological administration) in a nutritional excess.
How many to take?
The total (or almost) LACK of vitamins is defined as avitaminosis, while the partial one is defined as hypovitaminosis; on the other hand, the excess of vitamins can also determine toxicity reactions called hypervitaminosis.
As anticipated, vitamins are a group of MICRO-nutrients that boasts a wide range of functions; it follows that, by virtue of their heterogeneity, their metabolic demand also differs significantly between the molecules. Put simply, the recommended vitamin rations are all different from each other.
Vitamins must be taken according to the needs of the body; these differ significantly on the basis of sex, age, special physiological conditions, pathological conditions, physical activity, etc.
To meet the needs of the general population, the various research institutes have carried out numerous studies, both experimental and statistical; certainly, the most authoritative bibliographic sources are the American RDA (Recommended Daily Allowance) and the LARN people (Recommended Nutrient Intake Levels for the population of your country, composed and modified by the SINU: Society your country Human Nutrition); which is why, to the question "How many vitamins to take?", we will respond with the values disclosed by our national body: the LARN of the SINU
The scheme shown below is almost comparable to that of the LARNs; however, some values (such as those of vitamin E and vitamin K) are the result of arithmetic products between unit coefficients and other reference parameters (such as the total intake of vitamin F [essential fatty acids - AGE] or the weight body "physiological") suggested by the text itself.
We also remember that vitamin PP is expressed as Niacin Equivalents (NE) because it also includes endogenous vitamin B3 synthesized starting from tryptophan (1 mg every 60 mg of tryptophan); to have a more precise calculation of the recommended vitamin PP intake, the following arithmetic operation should be performed:
- mg of PP with the diet = 6,6 per 1000kcal introduced with the diet = 6,6 * (kcal with the diet / 1000).
The same indications can be applied to vitamins B1 and B2, through the products:
- mg of B1 with the diet = 0,4 every 1000 kcal introduced with the diet = 0,4 * (kcal with the diet / 1000)
- mg of B2 with the diet = 0,6 every 1000 kcal introduced with the diet = 0,6 * (kcal with the diet / 1000)
The amount of vitamin B6 is calculated on the basis of 15 mg / gram (g) of protein (about 15% of the energy intake is protein in both children and adults).
Vitamin A is in µg of Retinol Equivalents, but remember that 1µg of retinol = 6 µg of beta-carotene = 12 µg of other active carotenoids (NB. Pay attention to vitamin A supplementation during pregnancy!).
To cover the needs of vitamin D it is sometimes necessary to use fortified foods or complete with a supplementary supplementation.