Vitamins fall into two categories:
1, water-soluble vitamins: vitamin C, vitamin B group;
2, fat-soluble vitamins: vitamins A, D, E, K, etc.
Functions of various vitamins:
Vitamin A(Vit A), also known as retinol, actually includes all kinds of substances with retinol biological activity, namely Vit A 1 and Vit A2 from animal foods, β -carotene and other carotenoids from plant foods. Vitamin A is mainly involved in the structure and function of internal membrane. Therefore, it is related to normal growth and development, reproduction, vision and anti-infection. There are two main kinds of vitamin A obtained by human body from food. First, provitamin A, that is, various carotenoids, exists in plant foods, such as green leafy vegetables, yellow vegetables and fruits. First, vitamin A in animal foods mostly exists in animal livers, milk and dairy products (non-defatted) and eggs in the form of esters.
Vitamin D(Vit D) is a kind of compounds with biological activity of cholecalciferol, which can be converted into vitamin D3 and vitamin D2 by ultraviolet activation from vitamin D precursor, 7- dehydrocholesterol and ergosterol. Vitamin D is transformed into the active forms of 25-(OH)D3 and 1, 25-(OH)2D3 in the liver and kidney in vivo, and transported to the intestine, bones and kidneys, and works together with parathyroid hormone * * * to maintain the blood calcium level.
Vitamin C(Vit C)Vit C is reducible, and can scavenge free radicals together with other antioxidants such as glutathione to prevent lipid peroxidation. It also participates in the hydroxylation of cholesterol to form cholic acid, thus reducing the blood cholesterol content. When vitamin C is insufficient, it will affect collagen synthesis, resulting in delayed wound healing, fragile microvascular wall and bleeding to varying degrees. Because of the lack of gulonolactone oxidase, the human body cannot convert glucose into vitamin C, so vitamin C must be obtained from diet. If vitamin C in the diet cannot meet the needs, it can lead to vitamin C deficiency or deficiency, and vitamin C deficiency can cause scurvy.
Harm of taking a large amount of vitamin C: a few grams 1 can cause diarrhea and abdominal distension; 2. False negative results of fecal occult blood; 3. Decreased iron absorption, thalassemia, sideroblastic anemia and hemochromatosis; ④ Some patients have hyperoxaluria; 5 dialysis patients are prone to hyperoxalemia; Patients with glucose -6- phosphate dehydrogenase deficiency are prone to hemolysis.
Thiamine, also known as vitamin B 1, anti-neuritis factor, anti-beriberi factor. Participate in the metabolism of sugar and branched-chain amino acids in the body. Vitamin B 1 can regulate neurophysiological activities, which is related to heart activity, maintaining appetite, normal gastrointestinal peristalsis and digestive juice secretion. Vitamin B 1 deficiency is often caused by insufficient intake, increased demand and obstacles in absorption and utilization. It can also lead to liver damage and alcoholism. Long-term renal dialysis, total parenteral nutrition and long-term chronic fever can all occur. Serious deficiency can cause beriberi, which can be divided into dry beriberi, wet beriberi and infant beriberi. No toxic reaction was found when a large amount of vitamin B 1 was ingested.
Riboflavin, also known as vitamin B2, is an indispensable auxiliary group of various oxidase systems in the body. FMN and FAD (vitamin B2 is a component of FMN and FAD) are yellow enzyme auxiliary groups. Its function is electron transfer, which plays a controlling role in the respiratory chain reaction of cell metabolism and directly participates in redox reaction. It can also activate vitamin B6 and participate in the process of converting tryptophan into nicotinic acid. In addition, it is also related to the absorption, storage and mobilization of iron in the body, and also catalyzes the N- oxidation of various imines.
vitamin deficiency
Vitamins are a large class of substances with different chemical structures and physiological functions, which must be supplied through diet every day. When the supply is insufficient, it is easy to be insufficient. Vitamin deficiency is a gradual process in the body. At first, the reserve decreases, then it involves biochemical metabolism abnormalities, physiological function changes, and then histopathological changes, resulting in clinical symptoms and signs. Although vitamin deficiency is rare in China, subclinical deficiency is more common in some areas and some people. Because subclinical deficiency is not easy to find, but it has adverse effects on health, it needs special attention.
Vitamin C deficiency: Long-term lack of vitamin C in the diet will hinder the synthesis of collagen in the body and lead to scurvy. The early symptoms are burnout, followed by gum pain and bleeding, subcutaneous bleeding and slow wound healing. In severe cases, the teeth are loose, the gums are atrophied, the teeth fall off, and some mucous membranes bleed, which may cause symptoms such as nosebleeds and bloody stools. Children may have subperiosteal bleeding.
Thiamine deficiency: due to long-term insufficient intake, increased demand or obstacles in absorption and utilization. The nature and degree of its symptoms are related to the degree of deficiency, acute and chronic. Generally divided into the following categories: dry beriberi: with the symptoms of polyneuritis as the main symptom, there is ascending peripheral neuritis, which is characterized by numbness of fingers and toes, muscle pain and tenderness, especially gastrocnemius.
Wet beriberi: edema and heart symptoms are the main symptoms. If not treated in time, it will often lead to heart failure.
Infantile beriberi: Infants who mostly occur in February-May have a sudden onset and are in a hurry. Early loss of appetite, vomiting, excitement, rapid heartbeat, shortness of breath and difficulty. Cyanosis, edema, enlargement of the heart, heart failure and tonic spasm occur in the late stage, and they often die within 1-2 days after symptoms appear.
Riboflavin deficiency: mainly manifested as inflammation of eyes, mouth and skin. Eyes: conjunctival congestion, pericorneal vascular hyperplasia, and sometimes edema at the junction of cornea and conjunctiva.
Oral cavity: the mouth is wet and white, with cracks, pain and ulcers; Lip swelling, cracks, ulcers and pigmentation; Tongue pain, swelling, erythema and atrophy of tongue nipple.
Skin: seborrheic dermatitis. Common in sebum-rich parts.
Anemia: Vitamin B2 deficiency often interferes with the absorption, storage and mobilization of iron in the body, leading to the decrease of iron content, and even iron deficiency anemia in severe cases.
Others: Vitamin B2 deficiency also affects growth and development; Insufficient pregnancy can lead to fetal skeletal malformation.
Nicotinic acid deficiency: Nicotinic acid deficiency is a boil. Early symptoms are fatigue, fatigue, decreased working ability, poor memory and frequent insomnia. Typical symptoms are dermatitis, diarrhea and dementia, the so-called "three D" symptoms.
Vitamin A deficiency: When dietary vitamin A or provitamin A is insufficient, or absorption, storage and utilization are affected, vitamin A deficiency can often be caused. The manifestations are: decreased dark adaptation, night blindness and dry eye; Mucosal epithelial changes; Growth and development are blocked; Others: taste and smell are weakened, and appetite is reduced.
Vitamin D deficiency: lack of vitamin D in diet or insufficient sunlight are the two main reasons for vitamin D deficiency. Vitamin D deficiency leads to decreased absorption of calcium and phosphorus, decreased blood calcium level, bone inorganic obstruction, osteomalacia, infantile rickets and adult osteomalacia.
Vitamin e deficiency: vitamin e deficiency rarely occurs in humans, which may be due to the following reasons: vitamin e is widely found in food; Vitamin E is stored in almost all organs and tissues of human body. Vitamin e can be stored in the body for a long time.
Dietary sources of vitamins:
vitamin A
Green leafy vegetables, yellow vegetables, fruits, livers, milk and dairy products.
VD
Marine fish, liver, egg yolk, cream.
vitamin E
Oilseeds and vegetable oils
Vit B 1
Animal viscera, meat, beans, peanuts
Victor B2
Liver, kidney, heart, milk and eggs
Victor B6
Beans, meat, liver, fish
vitamin C
Fresh vegetables and fruits
folic acid
Liver, kidney, eggs, green leafy vegetables, yeast.
nicotinic acid
Liver, kidney, meat, fish, peanuts, grains.