Minerals do not have the energy value, but are necessary for the vital activity of the body.
They enter the body with food in the form of mineral salts. Minerals contained in food products and body tissues in significant quantities are macroelements. Macroelements are basic and acidic in nature. The main ones are calcium, magnesium, potassium, sodium, to acidic - phosphorus, sulfur, chlorine. Food products containing macronutrients of an acidic nature include meat, poultry, eggs, cottage cheese, cheese, bread, legumes, lingonberries, and cranberries.
Milk, kefir, yogurt, vegetables, many berries, fruits (especially almonds) contain macronutrients of the main character.
Calcium is the main component of bone tissue, the most important component of the blood coagulation system, an activator of a number of enzymes, hormones, plays an important role in many physiological and biochemical processes. The daily calcium requirement for an adult is 800 mg. It is better absorbed in the ratio of phosphorus 1: 1,5, and in the ratio of magnesium 1: 0,5 (0,6). The main source of calcium is milk and dairy products. In them, calcium is optimally balanced with phosphorus. Drinking half a liter of cow's milk ensures that 600 mg in the body is perfectly digestible calcium. Calcium in fruits and vegetables is well balanced, but it is not enough in these products. The unfavorable balance of calcium, phosphorus and magnesium in bread, meat and millet impairs the calcium absorption of these products. Phytic acids found in cereals and oxalic acid in spinach reduce calcium absorption. Calcium absorption is also reduced with excess fat intake.
Magnesium plays an important role in the transmission of nerve impulses and the normalization of the state of the nervous system, regulates calcium and cholesterol metabolism, has a vasodilating effect, helps to reduce blood pressure. The daily need for adult magnesium is 400 mg. The main sources of magnesium are various cereals, peas, beans, wholemeal bread. There is he and fish products, especially in canned food (sprats, pink salmon). Little magnesium in milk and dairy products, eggs, fruits.
Phosphorus regulates the functions of the central nervous system, the energy supply of the vital processes of the body. The daily need for adult phosphorus is 1200 mg; with increased physical exertion, the need for phosphorus increases. Most foods are rich in phosphorus, and therefore there is almost no shortage of food. Excessive intake of phosphorus is dangerous, especially in children during the first months of life. An excessive amount of phosphorus leads to a decrease in calcium in the body. This must be borne in mind when feeding babies in the first year of life with cow's milk, where there is more phosphorus in 5 — 7 times than in women's milk, and calcium in relation to phosphorus is less than in women. Milk and dairy products, meat, fish, grains and legumes are the richest in phosphorus. From plant sources, phosphorus is absorbed worse than from animal products.
Potassium is especially necessary to ensure the normal functioning of the circulatory organs, nervous excitation processes in muscles, and intracellular metabolism. Potassium increases urination. The daily need of an adult person in it is 3 — 5 g. Especially a lot of potassium in products of plant origin: soybeans, beans, peas, potatoes, seaweed, dried fruits - apricots, prunes, raisins, pears, apples. There is a lot of it also in milk.
Sodium is involved in the processes of intracellular and intercellular metabolism, in maintaining the osmotic pressure of protoplasm and biological fluids of the body, it takes an active part in water metabolism. Sodium content in food products is insignificant. It is not enough in potatoes, fruit; a few more in carrots, beets, cereals, meat and fish. Therefore, sodium enters the body mainly in the form of sodium chloride (salt). Although the need for sodium is small (about 1 g per day), modern man consumes it per day to 6 g, which corresponds to 15 g of table salt. In recent years, a relationship has been established between excess consumption of table salt and the occurrence of hypertension. It is recommended to limit the consumption of edible salt to 8 g per day, which corresponds to 4 g of sodium (3,2 g at the expense of the edible table salt itself and 0,8 g at the expense of receipt with food products).
Chlorine regulates osmotic pressure in cells and tissues, normalizes water metabolism, and also participates in the formation of hydrochloric acid in the stomach. The daily requirement for chlorine in an adult is 5 — 7 g, which is satisfied by sodium chloride (edible salt).
Sulfur is a necessary structural element of the amino acids methionine and cystine; she is a member of insulin, takes part in his education. Daily need for sulfur is adultman - about 1 g Sulfur is found mainly in animal products: beef, pork, sea bass, cod, horse mackerel, eggs, milk, cheese; in smaller quantities it is found in bread, cereals, and fruits.
Trace elements and their role in nutrition
Trace elements - a group of chemical elements present in humans and animals in low concentrations. The daily need for them is expressed in milligrams or fractions of a milligram. Trace elements have high biological activity and are necessary for the life of the organism. Such biomicroelements include iron, copper, cobalt, nickel, manganese, strontium, zinc, chromium, iodine, fluorine. The lack of these substances in the diet can lead to structural and functional changes in the body, and their excess can have a toxic effect.
On the globe, there are areas in the soil of which the number of trace elements may be more or less (biogeochemical provinces). The lack or excess of trace elements in these areas causes the emergence of various diseases among the population, such as endemic goiter, caries, fluorosis, blood diseases.
Iron, copper, cobalt, nickel are biomicroelements that are necessary for blood formation.
More than half of the total amount of iron in the body is contained in the hemoglobin of the blood. Iron participates in redox processes, is part of enzymes, stimulates intracellular metabolic processes. An adult's need for iron is 10 mg for men and 18 mg per day for women. It is very important that iron is regularly and in sufficient quantities supplied to the child's body, since its reserves are limited in children, and a lack of this trace element can lead to the development of anemia. Sources of iron are products of animal and plant origin. There is a lot of iron in the liver, kidneys, brains, rabbit meat, eggs, buckwheat, millet, legumes, apples, peaches. Meat products provide about 30% of the body's iron requirements. It is less in vegetables, berries and fruits. Bread made from finely ground wheat flour is relatively poor in iron. "
Copper is necessary for the synthesis of hemoglobin, enzymes, proteins, for the conversion of food iron to an organically bound form. Copper contributes to the normal functioning of the endocrine glands, the production of insulin, adrenaline. The need for adult copper is 2 mg per day. Most copper in the liver, in products of the sea, cereals, buckwheat and oatmeal, nuts. It is not enough in milk and dairy products. Since copper is widespread in products nutrition, its deficiency in adults almost never occurs.
The third (after iron and copper) trace element that is involved in blood formation is cobalt. It activates the formation of red blood cells and hemoglobin, affects the activity of some enzymes, is involved in the production of insulin. Cobalt is necessary for the synthesis in the body of cyanocobalamin (vitamin B 12). The need for an adult in cobalt is approximately 100 — 200 μg per day. Cobalt is low in food, but with a mixed diet it enters the body in sufficient quantities. Relatively much cobalt in sea plants, peas, beets, red currants, strawberries.
Nickel stimulates blood formation. But its excess is unfavorable for the body. A large amount of nickel is found in plants grown on the soil of "nickel" areas, in sea, lake and river water, in the body of marine animals and fish. The population of the "nickel" areas has an increased incidence of the cornea of the eyes.
The role of manganese in the vital activity of the organism is diverse, but its main feature is participation in the processes of bone formation. Manganese stimulates growth processes, is involved in the blood, the functions of the endocrine system, the metabolism of vitamins, the regulation of carbohydrate and mineral metabolism, has a lipotropic property. The need for manganese -10 mg per day. The manganese content in meat, fish, dairy products, eggs small. More in its cereals, legumes, nuts. Rich in manganese, coffee and tea. One cup of tea contains up to 1,3 mg of manganese.
The biological role of iodine is associated with its participation in the formation of thyroid hormone - thyroxin, which controls the state of energy metabolism, actively influences physical and mental development, tissue maturation, participates in the regulation of the functional state of the central nervous system, has a pronounced effect on the metabolism of proteins, fats, carbohydrates, water-salt metabolism. When iodine deficiency in the body disrupts the function of the thyroid gland, it increases in size, and goiter develops. Iodine in nature is distributed unevenly. Its greatest amount is contained in sea water, air and soil of coastal areas, the smallest - in the air and soil of mountainous areas. High iodine content is detected in marine fish (especially in cod), shrimp, sea kale. Storage and culinary processing of food products lead to a significant loss of iodine (up to 65%). The optimal daily intake of iodine for a person is 100 — 200 mcg. This need for the body is covered mainly by food. In areas where there is a shortage of iodine in the water, the population is provided with iodized table salt.
Fluorine is involved in the development of teeth, bone formation, normalizes phosphorus-calcium metabolism. Unfavorable is both excess fluorine intake and its deficiency. The main source of fluorine is drinking water, I l of which contains about 1 mg of this trace element. Usually a person with water gets —1,5 mg of fluoride per day. In food fluoride is not enough. With food 0,23 — 0,35 mg of fluorine per day enters the body. It is found in fish, lamb, veal, oatmeal, nuts. With insufficient intake of fluorine, dental caries develops - especially when fluoride content in water is less than 0,5 mg / l. In the USSR, in areas with a low fluorine content in water, drinking water is fluorinated, bringing it to 0,7 — 1,5 mg / l. When fluoride is in excess in the body, fluorosis develops - the mottling of tooth enamel and its degeneration. Fluorosis is common in areas where the fluorine content in water exceeds
mg / l. In such cases, the drinking water is defluorized, that is, it reduces the amount of fluoride.
The role of zinc in the body is no less important than other trace elements. Zinc is found in many enzymes, is involved in blood formation, the synthesis of amino acids. It is necessary for the normal activity of the endocrine glands, is part of insulin, has lipotropic properties, normalizes fat metabolism. The need for zinc - 10 — 15 mg per day. Zinc is widely represented in food. Liver, meat, egg yolk, mushrooms are high in zinc. A lot of it in cereals and legumes, bran, garlic, potatoes, beets, nuts.
Chromium is involved in the regulation of carbohydrate and mineral metabolism, the metabolism (transformation) of cholesterol, activates a number of enzymes. In food, it is contained in a small amount, so with a monotonous, unbalanced diet, chromium deficiency develops very quickly. Chromium is abundant in beef liver, meat, poultry, cereals and legumes, pearl barley, rye wallpaper flour.