Healthy eating: what do you need to know for each person?

Nutrition is the science of food and its impact on human health. Nutrients are chemical compounds contained in food and used by the body for growth, life support and energy. Nutrients (nutrients) that are not synthesized by the body are the most valuable (irreplaceable) and therefore must be obtained with food. These include vitamins, minerals, some amino acids and fatty acids. Nutrients, which are synthesized by the body from other compounds, even though they can be obtained with food, are not indispensable. Macronutrients are necessary for the body in a relatively large amount, trace elements are needed in small amounts.

Lack of certain nutrients can lead to various diseases (for example, kwashiorkor, pellagra), as well as other disorders. Excess consumption of macronutrients leads to obesity, and the excess consumption of micronutrients can cause toxic manifestations.

[1], [2], [3], [4], [5], [6]

Macronutrients

In general, food consists of macronutrients, which serve as a source of energy and many essential nutrients. Carbohydrates, proteins (including essential amino acids), fats (including essential fatty acids), macronutrients and water are macro elements. As sources of energy, carbohydrates, fats and proteins are interchangeable; fats produce 9 kcal / g (37.8 kJ / g); proteins and carbohydrates - 4 kcal / g (16.8 kJ / g).

Carbohydrates

Carbohydrate food is split to form glucose and other monosaccharides. Carbohydrates increase the level of glucose in the blood and replenish the energy reserve. Simple carbohydrates, mainly monosaccharides or disaccharides, consist of small molecules and are low molecular weight compounds that are rapidly absorbed. Complex carbohydrates are high molecular compounds, the molecules of which form monosaccharides upon cleavage. Complex carbohydrates increase the level of glucose in the blood slowly, but longer. Glucose and sucrose are simple carbohydrates; starch and cellulose (cellulose) - complex carbohydrates (polysaccharides).

The glycemic index shows how quickly carbohydrates increase the level of glucose in the blood. The values of the series are expressed from 1 (the slowest increase) to 100 (the fastest rise, equivalent to pure glucose). However, in fact, the rate of increase in blood glucose also depends on the nature of the carbohydrates in the food.

Carbohydrates with a high glycemic index quickly increase blood glucose levels to high digits. As a result, the level of insulin increases, which causes hypoglycemia and the appearance of hunger, which contribute to the consumption of excess calories, and consequently, weight gain. Carbohydrates with a low glycemic index increase blood glucose more slowly, resulting in a postprandial insulin level in the blood below and a feeling of hunger is less pronounced. As a consequence, a more favorable lipid profile is created and, consequently, the risk of obesity, diabetes and its complications decreases.

Proteins

Nutritional proteins are cleaved to form peptides and amino acids. Proteins are necessary to maintain life, renewal, functioning and growth of tissues. However, if the body does not receive enough calories from the depot (especially fats) or from food, the protein can be used as an energy source.

Glycemic index of some products

Category	Name	Index
Beans	Beans Red lentils	33 27
Bread	Soya Bread rye Bread white Whole wheat	14 69
Cereals	All Bran Corn Flakes Oat Flour Air Rice Wheat Flakes	54 83 53 90 70
Dairy	Milk, ice cream,	34-38
Products	Yogurt
Fruit	Apples Bananas Oranges Orange juice Strawberry	61 43 32
Corn	Barley Brown rice White rice	66
Pasta	-
Potatoes	Instant mashed potatoes (white) Puree (white) Sweet potatoes	86 50
Snacks	Corn Chips Oatmeal Cookies Potato Chips	57 56
Sugar	Fructose Glucose Honey, Refined sugar	100 91 64

The body's use of protein food for tissue formation is a net intake of protein (a positive nitrogen balance). In catabolic states (for example, starvation, infections, burns) associated with damage to body tissues, proteins can be used more than obtained from food, which leads to a net loss of protein (negative nitrogen balance). Nitrogen balance is the best determining factor of the difference between the amount of nitrogen consumed and the amount of nitrogen excreted by the body with urine and feces.

Of the 20 amino acids, 9 are essential amino acids; they are not synthesized in the body and must be obtained from food. Adults need 8 amino acids, and children from 0 to 1 year require additional histidine.

At normal weight, the need for food proteins is interrelated with the rate of growth, which decreases from the infant age to the adult. The protein requirement is reduced from 2.2 g / kg in 3-month-old infants to 1.2 kg / g in 5-year-olds and 0.8 kg / g in adults. The need for proteins corresponds to the need for essential amino acids. Adults who want to reduce muscle mass, need a minimum amount of proteins.

The amino acid composition of proteins varies widely. Biological value reflects the similarity of the amino acid composition of a protein to animal tissue proteins. The most harmonious is the egg white, the biological value of which is assumed to be 100. The animal proteins of milk and meat have a high biological value (~ 90); proteins of cereals and vegetables have a low biological value (-40); some other sources of protein (for example, gelatin) have a biological value equal to 0. The amino acid composition of the individual proteins that make up the diet determines the overall biological value of the diet. According to the RDA [recommended daily requirement (dose)], a mixed diet with a biological value of 70 is recommended.

Fats

Fats are split to form fatty acids and glycerin. Fats are necessary for the growth of tissues and the production of hormones. Saturated fatty acids, which are part of animal fats, retain a solid state at room temperature. Vegetable fats, except palm and coconut oils, have a liquid state at room temperature; they contain high concentrations of monounsaturated fatty acids or polyunsaturated fatty acids. Partial hydrogenation of unsaturated fatty acids produces trans fatty acids.

The most important (essential) fatty acids (IVLC) are -6 (n-6) linoleic and -3 (n-3) linolenic acids. Other -6 acids (eg arachidonic acid) and other -3 fatty acids [eicosapentenic (eicosapenoenoic acid), docosahexone acid] are also necessary for the body, but they can be synthesized from IVH.

IVC is necessary for the formation of various unsaturated fatty acids (eicosanoids), including prostaglandins, thromboxanes, prostacyclins and leukotrienes. A-3 Fatty acids reduce the risk of coronary artery disease.

The need for basic fatty acids is different depending on age. Adults require an amount of linoleic acid equivalent to at least 2% of the total calorie requirement, and linolenic acid, respectively, 0.5%. Vegetable oils are rich in linoleic and linolenic acids. Oils produced from saffron, sunflower, corn, soy, primrose, pumpkin and wheat germ, are rich in a large amount of linoleic acid. Fats of sea fish and oils made from flaxseed, pumpkin, soy and hemp are rich in a large amount of linolenic acid. Seafood fats also supply the body in large quantities with some other 3 fatty acids.

In the United States, the main food source of trans fatty acids is vegetable oil obtained as a result of hydrogenation. Trans fatty acids increase LDL cholesterol and lower LPV cholesterol; they also independently increase the risk of coronary artery disease.

Macronutrients

Na, CI, K, Ca, P and Mg are required in relatively large quantities daily (see Tables 1-3, 1-4 and 5-2).

Water. Water is classified as a macro-nutrient, since its requirement for energy consumption is 1 ml / kcal (0.24 ml / kJ), or about 2500 ml / day. The need for water changes with fever; in warm or cold climates; at high or low humidity.

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Trace Elements

Vitamins and minerals as trace elements are required in a small amount.

Water-soluble vitamins are vitamin C (ascorbic acid) and eight elements vitamin B complex: thiamine (vitamin B1, riboflavin (vitamin B ₂ ), nicotinic acid, piri doksin (vitamin B ₆ ), folic acid, cobalamin (vitamin B12), biotin and pantothenic acid.

Fat-soluble vitamins include retinol (vitamin A), cholecalciferol or ergocapciferol (vitamin D), a-tocopherol (vitamin E), and phylloquinone and menaquinone (vitamin K). Only vitamins A, E and B accumulate in case of significant changes in the body.

The basic trace elements include iron, iodine, zinc, chromium, selenium, manganese, molybdenum and copper. In addition to chromium, each of them is part of the enzymes or hormones involved in metabolism. With the exception of iron and zinc, the shortage of micromineral in industrialized countries is rare.

The importance of other minerals for humans (for example, aluminum, arsenic, boron, cobalt, fluorine, nickel, silicon, vanadium) has not been proven. Fluoride, although not a basic microelement, is involved in the prevention of caries, forming a composite with Ca, which stabilizes the mineral matrix of the teeth. All micronutrients are toxic in large quantities, and some of them (arsenic, nickel and chromium) can cause cancer.

Other food substances

The typical composition of food consumed daily by a person contains more than 100,000 reactive substances (for example, coffee contains 1000). Of these, only 300 are nutrients (nutrients) and only some of them are indispensable. But many substances that do not have nutritional value, contained in food, are useful. For example, food additives (preservatives, emulsifiers, antioxidants, stabilizers) improve the quality of products and their stability. Microcomponents (for example, spices, indifferent substances, changing odor and taste, aroma, color, chemically active substances of vegetable origin and many other natural products) improve the appearance and taste of food.

Fiber, found in various forms (for example, cellulose, hemicellulose, pectin, resin), strengthens the peristalsis of the gastrointestinal tract, prevents constipation and improves the course of diverticulosis. It is suggested that cellulose increases the rate of elimination of substances produced by colon bacteria and contributing to the development of cancer. Epidemiological studies have shown a close relationship between the development of colon cancer and low fiber intake, the beneficial effects of fiber on functional bowel disorders, Crohn's disease (during remission), obesity and hemorrhoids. Digested fiber (found in fruits, vegetables, oats, barley and beans) reduces postprandial increase in glucose and insulin in the blood and helps lower cholesterol.

A typical diet of Western countries provides for low fiber intake (approximately 12 g / day) due to high consumption of highly purified flour, wheat, low consumption of fruits and vegetables. It is strongly recommended to increase the intake of fiber by about 30 g / day, by consuming more vegetables, fruits and high-fiber cereals.