What vitamins should be in human nutrition
Vitamins are low molecular weight components of food that are irreplaceable constituents of enzyme molecules. Currently, about 30 vitamins have been discovered. The value of vitamins in human nutrition is very great. Their chemical structure is known, the physiological role, the value of individual vitamins for the life of humans and animals has been established. The human body is not able to synthesize vitamins, therefore their content in tissues depends on the intake with food.
Vitamins in food
Vitamins in the diet, their assimilation develops a partial vitamin deficiency – hypovitaminosis. Its consequences are various violations of physiological functions, in particular, the metabolism suffers significantly. At the same time, people have weakness, increased fatigue, disturbance of normal sleep, appetite. All this affects the general state of human health and can lead to a decrease in performance. Avitaminosis – the complete absence of one or more vitamins – is rare, with gross violations of the diet or with diseases that disrupt the absorption of certain vitamins.
All vitamins in nutrition can be divided into two large groups: fat-soluble vitamins – A, D, E, K, and water-soluble vitamins – C and B vitamins. Fat-soluble and water-soluble vitamins have different effects on the body …
A characteristic feature of fat-soluble vitamins is that they can accumulate in the body. If the intake of such vitamins with food exceeds the daily requirement, then their excess is stored “in reserve”. The resulting reserves can be stored for up to a year or more and spent as needed. Therefore, in people who eat well, only a relatively prolonged “vitamin starvation” can cause pronounced signs of a lack of fat-soluble vitamins. Too much intake of fat-soluble vitamins into the body is dangerous, since hypervitaminosis can cause various undesirable consequences.
Water-soluble vitamins in human nutrition almost do not accumulate in the body, and if more of them are supplied with food than necessary, then the excess is excreted in the urine. Excessive intake of water-soluble vitamins sometimes also leads to hypervitaminosis.
The daily intake of most vitamins ranges from a few micrograms (millionths of a gram) to several tens of milligrams. The amount of vitamins in food is measured in milligrams per 100 g of the product (mg%) or in micrograms per 100 g (μg%). Some vitamins are measured in international standard units (ME), which correspond to a specific number of micrograms for each vitamin.
So-called vitamin-like substances have properties similar to vitamins.
Water-soluble vitamins in nutrition
Vitamins in human nutrition can be divided into water-soluble vitamins. The functions of water-soluble vitamins and their characteristics should be considered within the framework of specific elements.
Vitamin C (ascorbic acid)
Vitamin C is involved in all metabolic processes, especially in the metabolism of carbohydrates and proteins, and normalizes the activity of many systems and organs. Ascorbic acid has a positive effect on liver function, increases the strength of blood vessels, makes them elastic and impermeable to blood components. It inhibits the excessive deposition of fatty substances in the vessels, thereby preventing the development of atherosclerosis, activates and regulates the hematopoietic system, strengthens the immune system, helps the absorption of iron, and also reduces the harmful effects of certain medicinal substances and industrial poisons (lead, arsenic and others). Vitamin C prevents the formation of carcinogenic substances in the intestines from bile acids and nitrates and nitrites from canned and smoked food, vegetables and fruits.
In the absence of a sufficient amount of vitamin C in a person’s food, the normal vital activity of the whole organism is disrupted, with a prolonged absence, a serious disease develops – scurvy. Another name for this disease is grief, and the word “ascorbic” can be translated as “antiscorbutic”. Gums swell with scurvy, ulcers form on them, teeth loosen and fall out, first point hemorrhages appear in the skin and muscles, which later turn into extensive bruising. Hemorrhages are most often seen in the lower extremities. The legs are swollen, and there is severe pain when walking.
Vitamin C is not only an antioxidant itself, but also protects other antioxidants (in particular, vitamin E and beta-carotene) from free radical damage.
The body of an adult healthy person contains about 5 g of ascorbic acid. Its concentration is especially high in the liver, kidneys, heart and brain.
The daily intake of vitamin C for a healthy adult is 70-100 mg. The need for vitamin C increases when a person is engaged in hard physical labor, performs strenuous neuromuscular work, and works in hot or cold climates.
Citrus fruits (oranges, grapefruits, tangerines, lemons) contain 40-60 mg% of vitamin C; broccoli, cauliflower, red cabbage – 50-70 mg%; strawberries, kiwi, currants – 120 mg%; red and green peppers – 250 mg%. A small amount is found in potatoes and tomatoes – 20-30 mg%. Vitamin C is practically absent from meat and animal products.
Vitamin C is the most unstable. It is destroyed by heat, light, oxygen in the air. During storage, its content in vegetables, fruits and berries decreases rapidly: after 2-3 months of storage in most plant products, vitamin C is destroyed by half. An exception is sauerkraut, in which vitamin C (20 mg%) is formed during fermentation. During thermal processing of food, especially during frying and cooking, as well as during long-term storage and reheating of ready-made meals, the loss of vitamin C reaches 30-90%. To reduce the loss of vitamin C during cooking, vegetables and fruits should be immersed in boiling water and boiled for no longer than necessary to soften them. Finely chopping fresh vegetables and fruits increases the surface that comes into contact with the air and promotes the oxidation of vitamin C. 3 hours after cooking vegetable salad, the content of vitamin C decreases by 70-80%, and after 6 hours it is almost completely destroyed. The degree of destruction of the vitamin is also adversely affected by metals (copper, iron). Therefore, you cannot cook food in copper or cast iron dishes.
Smoking, including passive smoking, destroys vitamin C in the body. Smokers, if they cannot part with a bad habit, need an increased amount of vitamin C.
The toxicity of vitamin C is extremely low. Some scientists believe that high doses of this vitamin can cause kidney stones and other problems, but no definitive evidence has been found for this.
There is a whole group of substances – bioflavonoids (rutin, kakhetin, citrine, etc.). The role of vitamin P is to facilitate the absorption of vitamin C and strengthen blood capillaries, therefore vitamin P is recommended for strengthening blood vessels. In addition, bioflavonoids have anti-allergic effects. With a lack of vitamin P, capillary fragility and permeability increase and other symptoms appear, similar to hypovitaminosis C. As a rule, bioflavonoids are present in the same foods as vitamin C. The richest natural source of vitamin P is chokeberry berries. They contain 4000 mg% bioflavonoids, that is, 4 g per 100 g of berries. There are a lot of flavonoids in black currants – 1000-1500 mg%, cherries – 1300-2500 mg%, dark-colored cherries – 200-900 mg%, quince – 200-800 mg%, pomegranates – 200-700 mg%, in citrus fruits – about 500 mg%. Bioflavonoids are found in sufficient quantities in most vegetables and fruits: in dill – 170 mg%, in carrots – 50-100 mg%, in beets – 40-75 mg%, in white cabbage – 10-70 mg%, in potatoes – 15 -35 mg%. The daily requirement of an adult for vitamin P is 35-50 mg. The ascorutin tablet, which is prescribed for diseases associated with increased vascular permeability, contains 50 mg of vitamins C and R.
Vitamin D is a regulator of calcium and phosphorus metabolism. It promotes the absorption of calcium in the intestines, its deposition in the bones. Children with vitamin D deficiency develop rickets. With rickets, the bones of the skull, chest, and spine are deformed. Curvature of the legs is especially common. In the early stages of the disease, vitamin D treatment can correct the deformity, but in later stages it becomes irreversible. In children, muscle weakness is also noted, in severe cases, the liver, spleen and other organs are affected.
The best way to prevent vitamin D deficiency is to stay in the sun. When the skin is exposed to ultraviolet rays, vitamin D is formed in skin cells from its precursor, dehydrocholesterol. Vitamin D deficiency in adults causes osteoporosis (degeneration and loosening of bone tissue) and osteomalacia (softening and deformation of bones). Hypovitaminosis D and calcium metabolism disorders are not uncommon in pregnant women who have been deprived of sunlight for a long time and who consume high-carbohydrate foods, which are low in calcium and phosphorus. Osteoporosis is very common in older women. This is primarily due to hormonal imbalances and (to a lesser extent) to low consumption of animals and dairy products, which contain a lot of phosphorus and calcium. In older men, osteoporosis is rare.
In case of insufficient exposure to sunlight on the skin, vitamin D must be ingested with food or administered as a preparation. The requirement for vitamin D from food or vitamin preparations for adults is 2.5 μg – 100 IU (international units). In children, the daily requirement is higher – 400 IU (10 μg).
Vitamin K is involved in blood clotting processes. It is necessary for the production of prothrombin in the liver and the activation of various links of the blood coagulation system. Vitamin K is a part of cell membranes, enhances the action of the endocrine glands (pituitary gland, adrenal glands, thyroid gland) and ensures contractility of the smooth muscles of the digestive tract.
The daily requirement for vitamin K is 0.2-0.3 mg. A person completely receives the required amount of this vitamin when eating ordinary food; at the same time vitamin K is synthesized by intestinal bacteria. Therefore, in healthy people, the phenomena of vitamin K deficiency usually do not occur.
Vitamin K is found mainly in plant products: spinach – 5 mg, cauliflower, pumpkin – 4 mg%, cabbage – 2 mg%, tomatoes – 0.4 mg%, strawberries – 0.1 mg%. Of animal products, a lot of vitamin K is contained only in the liver – 0.6 mg%.
As with other fat-soluble vitamins, bile is required for the absorption of vitamin K in the intestines. With a weakening of the flow of bile due to blockage of the biliary tract, in the presence of gallstones and other diseases associated with a complete absence or low flow of bile into the intestine, hypovitaminosis or vitamin deficiency can occur. Similar phenomena can also be observed in diseases of the intestine, in which the process of assimilation is disrupted fat.
K-vitamin deficiency can develop as a result of prolonged use of sulfa drugs and antibiotics, as well as some other drugs that suppress or completely stop the formation of vitamin K by intestinal bacteria. With prolonged irrational use of drugs that reduce blood clotting, vitamin K hypovitaminosis can also develop.
Synthetic vitamin K is contained in the preparation “Vikasol”, which is used for vitamin K deficiency and various kinds of bleeding.