Edited by Doctor Alessio Dini
By nutritional element we mean that substance that is fundamental for our metabolism, therefore for the production of energy necessary for life.
The nutritional principles are contained in food in various ways and depending on the need they are classified into macronutrients and micronutrients.
Proteins
Nitrogen molecules made up of carbon, hydrogen, oxygen and nitrogen, are among the most complex organic compounds and are essential constituents of all cells. From a chemical point of view, proteins are macromolecules formed by the union of simpler units, amino acids. Amino acids join together through a covalent bond called peptide bond.
Proteins perform multiple functions and account for about 12-15% of body mass.
The amino acids present in nature are numerous, but only 20 of them can be used by our body for protein synthesis. Eight 8 of these are defined as "essential", ie they are not synthesized in sufficient quantities and must therefore be taken with the diet.
Foods of animal origin have a better amino acid profile because they generally contain all the essential amino acids in good quantities. Unlike these, foods of plant origin usually have deficiencies in one or more essential amino acids. However, these deficiencies can be overcome through right food associations, such as pasta and beans. In this case we speak of mutual integration because the amino acids that the pasta is lacking are supplied by the beans and vice versa.
Normally 92% of the proteins introduced with the diet are absorbed (97% of animal ones and 78% of vegetable ones).
Nutritionists recommend taking during the day a quantity of protein equal to about 15-20% of the total daily caloric intake, equal to 0.8-1 g of protein per kg of body weight. 2/3 of these proteins should derive from products of animal origin and 1/3 from products of plant origin.
Protein is abundant in meat, poultry, fish, milk, cheese, yogurt, but also in vegetables, legumes, grains, nuts, seeds and vegetables.
An excessively protein diet can result in:
- accumulation of storage fat (if the proteins included go beyond the total caloric requirement);
- excessive formation of toxic nitrogenous waste (ammonia, creatinine, uric acid, urea, etc.).
Excess nitrogenous waste creates difficulties in the replacement and reconstitution of new cellular structures, kidney and liver fatigue, blood acidosis, digestive difficulties and disorders.
Carbohydrates
Carbohydrates, also called carbohydrates, are substances made up of carbon, hydrogen and oxygen. They have molecular formula (CH2O) n and are mainly contained in foods of plant origin.
Based on their chemical structure, carbohydrates are classified into simple (monosaccharides and disaccharides) e complex (oligosaccharides and polysaccharides).
Monosaccharides are classified. based on their number of carbon atoms in trioses, tetroses, pentoses, hexoses and so on; hexoses (glucose, fructose, galactose) are the most important from a nutritional point of view.
Glucose is used as a source of energy by both animals and plants; it is the main product of photosynthesis and is the fuel of cellular respiration. When present in excess, glucose is converted into glycogen, the glucose polymer and the main energy reserve of animals.
Simple and / or complex sugars, albeit in very variable percentages, are almost present in all foods.
Particularly rich in carbohydrates complex are mainly cereals (wheat, corn, rice, barley, spelled, oats etc.), potatoes, chestnuts, some legumes (in particular, peas and beans), pumpkin and roots (such as carrots, sugar beets etc. .).
Sugars simple they are more present in fruit, especially in ripe fruit and in some types more than in others (bananas, figs, persimmons, pears, tropical fruits, peaches, apricots). As well as, of course, in honey, honeydew and natural syrups.
Carbohydrates should constitute the predominant share of the daily caloric intake, ideally about 55-65%, of which 80% should be of the complex type.
Excessive consumption, in addition to promoting weight gain and dental pathologies, predisposes to the development of insulin resistance, type 2 diabetes, and hormonal alterations of different types.
Lipids
Heterogeneous group of molecules, united by the characteristic of being insoluble in water.
They perform important functions in the body, including that of energy supply (1 g of lipids provides 9 Kcal, against 4 Kcal of carbohydrates and proteins); they are constituents of cell membranes (phospholipids and cholesterol); they are precursors of compounds that in the " organism perform important regulatory functions (steroid hormones, vitamin D); they are our subcutaneous thermal insulator and support our organs.
The most important lipids from the point of view of human nutrition are: fatty acids, triglycerides, phospholipids and cholesterol.
We remind you that lipids are also essential for a balanced diet and that among the unsaturated fatty acids we find essential fatty acids such as alpha-linolenic and linoleic acids, important precursors of prostaglandins, thromboxanes and leukotrienes, substances that mediate the response inflammatory and intervene in the immune and cardiovascular systems.
Essential fatty acids are contained in fish, nuts, sunflower oil, corn and some plant extracts.
Vitamins
Vitamins are a very heterogeneous set of chemical substances, normally necessary in minimal quantities for the needs of the organism, in which they regulate a series of metabolic reactions, often functioning as coenzymes. Vitamin deficiency is usually defined as hypovitaminosis when the vitamin is present in insufficient quantities in the organism, and avitaminosis in the much rarer cases in which it is totally absent.
Vitamins can be divided into two large groups:
- water-soluble: they cannot be accumulated by the organism, therefore to be taken daily with the diet. These are all the B vitamins, including folic acid, vitamin H, PP and C.
- fat-soluble: they are absorbed together with dietary fats and accumulated in the liver. The deficiency therefore manifests itself as a result of a lack of recruitment for a long time. Vitamin A, D, E and K are part of it.
Mineral salts and water
Mineral salts are inorganic substances which, while representing only 6% of body weight overall, perform essential functions for human life: in fact, they participate in cellular processes, such as the formation of teeth and bones, and are involved in the regulation of balance. hydrosaline, in the activation of numerous metabolic cycles and are determining factors for the growth and development of tissues and organs.
Mineral salts do not directly provide energy, but their presence allows to carry out precisely those reactions that release the energy we need.
They cannot be synthesized independently, they are assimilated through water and food, or in the form of a condiment added to food, such as table salt.
Mineral salts can be divided into:
- Macroelements: they are present in the organism in discrete quantities. The daily requirement is of the order of grams or tenths of a gram.
- Trace elements or microelements: they are present only in trace amounts in the body and the daily requirement ranges from a few micrograms to a few milligrams.
Water: fundamental component of our diet. It is not for nothing that the human body is made up of 60% water. Furthermore, the body has no reserves from which it can draw. The daily intake should be at least 1.5 - 2 liters.
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