Vitamins Sagda kamal eldein 30/1/2019 0919106108
The discovery of the first vitamin was published in 1911 by a Polish biochemist, Casimir Funk. The term vitamine is derived from the words vita (meaning lifegiving) and amine (were originally thought to be amines). Although not all vitamins are amines, they are organic compounds required by humans in small amounts from the diet. Usually only a few milligrams (mg) or micrograms (μg) are needed per day, but these amounts are essential for health.
Most vitamins cannot be made by the body, so have to be provided by the diet. An exception is vitamin D which can be obtained by the action of sunlight on the skin. Small amounts of a B vitamin (niacin) can be made from the essential amino acid, tryptophan. Vitamin K is formed by bacterial action in the large intestine.
Vitamins do not contain energy per se, but they help regulate energy process in the body. Vitamins have a variety of functions in the body: some are co-factors in enzyme activity, some are antioxidants (prevent oxygen from doing damage in the body) and one (vitamin D) is a pro-hormone. If insufficient amounts of vitamins are available to the body because of a poor diet or some medical condition (e.g. malabsorption of nutrients), specific symptoms will appear and can develop into a deficiency disease. Vitamin deficiency diseases are rare in the westernized society, but still occur in some parts of the world. Vitamins and minerals are measured in milligrams (mg), micrograms (µg) and international units (IU).
How much of the vitamins do we need? The body requires different amounts of each vitamin because each of them has a different function. People have different requirements too, according to their age, gender, level of activity and state of health.
Vitamin supplements Although most people are able to meet their requirements for vitamins by eating a varied diet, there are certain groups of the population who have higher than normal requirements, e.g. the sick, those taking certain drugs and pregnant women. Infants and young children are recommended to have supplements of vitamins A and D for at least 2 years. Some women many require additional iron if menstrual losses are high. The evidence for benefits from antioxidant supplementation for athletes is mixed.
Vitamins have been traditionally grouped into two categories: the fat soluble vitamin (A, D, E, K), and the water soluble vitamins (C, B complex). Originally, vitamins were given letters (A, B, C, etc.) but now are usually referred to by their chemical names, e.g. folate.
The fat soluble vitamins are stored in the body and their deficiencies are relatively rare. On the other hand, excessive intakes may be toxic. The water soluble vitamins are not stored to any significant extent in the body. Excess supplements of these vitamins are usually excreted in the urine.
Vitamin A (Retinol) Retinol and beta carotene preformed vitamin A. Beta carotene can be converted to retinol in the body; 6mg of beta carotene is equivalent to 1mg of retinol. sources: Retinol is found in liver, whole milk, cheese and butter. Carotenes are found in milk, carrots, dark green leafy vegetables and orange coloured fruits, e.g. mango and apricots. The law states that margarine must be fortified with vitamin A (and vitamin D). RDA (retinol): 1000 mcg of retinol, or 5000 IU, for adult males and 800 mcg of retinol, or 4,000 IU, for adult females one glass of milk provides 10% of the RDA one medium carrot provides 200% of the RDA a serving of liver provides 900% of RDA
Major function in the body vital to good vision prevents night blindness antioxidant necessary for healthy skin, hair growth keeps mucous membranes healthy promotes bone development
Vitamin A is stored in the body in relatively large amounts, and thus deficiencies are rare. deficiency: night blindness, intestinal infections, impaired growth hypervitaminosis: nausea, headache, fatigue, liver and spleen damage, skin peeling, risk of birth defect It is for this reason that women who are pregnant, or who might become pregnant, are advised not to take vitamin A supplements unless they are advised to do so by a health professional. Liver and liver products may contain a large amount of vitamin A, so these should also be avoided.
Carrot 1 big carrot - 78 g vit. A - 270% vit. C - 10% Calcium - 2% Iron - 0%
Spinach 1 1/2 cup - 85g vit. C - 25% vit. A - 70% Calcium - 6% Iron - 20% It is full of vitamin A, iron, folate and magnesium
Apricots 3 apricots - 114g vit. C - 20% vit. A - 45% Calcium - 2% Iron - 2% It is full of vit. A and potassium.
Apricots dried 6 pieces - 42g vit. C - 0% vit. A - 50% Calcium - 2% Iron - 10%
Lettuce 1 1/2 cup - 85 g vit. C - 6% vit. A - 40% Calcium - 4% Iron - 0%
Vitamin D (Cholecalciferol) Vitamin D is found in foods in two main forms, mostly as cholecalciferol and in small amounts as ergocalciferol. The physiologically active form is calcitriol, which is the hormone of this vitamin. The ultraviolet rays from sunshine convert a compound found in the skin into cholecalciferol which is released into the blood and is eventually converted by the liver and kidneys into active hormone calcitriol. In this form it works as a hormone in controlling the amount of calcium absorbed by the intestine. It is also essential for the absorption of phosphorus and for normal bone mineralization and structure.
sources: fish liver oils, eggs, tuna, salmon, fortified foods like dairy products and margarine, and some breakfast cereals, action of sunlight on the skin = deficiencies are unusual RDA (cholecalciferol): 10 micrograms or 400 IU one glass of milk provides 25% of RDA one tin of sardines provides 100% of RDA
Major function in the body acts as a hormone to increase intestinal absorption of calcium promote bone and tooth formation prevents rickets in children and osteomalacia in adults
deficiency: rickets in children and osteomalatia in adults, Deficiencies are rare. Some groups of people (e.g. older adults, and children) are at risk of vitamin D deficiency because of low vitamin D intake from food and/or inadequate exposure of skin to sunshine. hypervitaminosis: loss of appetite, nausea, joint pains, loss of muscle tone, damage to soft tissues such as the kidney, heart, and blood vessels due to deposits of calcium. In general, vitamin D supplement are not recommended.
Vitamin E (alpha-tocopherol) Vitamin E is a group of compounds called tocopherols and tocotrienols, of which alpha tocopherol is the most active. sources: vegetable oils, margarine, green leafy vegetables, wheat germ, whole grain products, egg yolks RDA (tocopherol): 10 mg for men, and 8 mg for women one tablespoon of margarine provides 74% of RDA
Major function in the body helps breakdown polyunsaturated fats antioxidant, protect cells against oxidative damage by free radicals, for example oxidation of the lipids in the cell membranes plays a role in aging, sexual performance, or prevention of cancer and/or heart disease
deficiency: disruption of red blood cell membranes, anemia Deficiencies are extremely rare. hypervitaminosis: headache, fatigue, diarrhea, general lack of toxicity with doses up to 400 mg Vitamin E is one of the most popular nutrient supplements. There are many health claims for supplementation slowing of the aging process or an improvement in sexual potency.
Vitamin K (phylloquinone) Vitamin K is found in foods from both plant and animal sources and is also made by bacteria in the gut. sources: pork and beef liver, eggs, spinach, cauliflower, broccoli, tomatoes RDA: 80 µg for men, 65 µg for women
Major function in the body essential for clotting of blood (vitamin K is named antihemorrhagic vitamin) normal bone structure
deficiency: increased bleeding and hemorrhage Deficiency states are rare, they may occur in some individuals when antibiotic medications kill the intestinal bacteria that produce the vitamin. hypervitaminosis: thrombosis, vomiting
Vitamin C (Ascorbic acid ) Vitamin C is the most famous vitamin. sources: almost exclusively in foods from plant sources (citrus fruits, broccoli, peppers, kiwi, strawberries, potatoes, tomatoes), although fresh milk and liver contain small amounts. RDA: 80 mg one kiwi, small orange or 4 strawberries provides 100% of RDA
Major function in the body helps form collagen helps in growth and repair of body tissue and blood vessels prevents scurvy a strong antioxidant aids in absorption of iron helps regulate the metabolism of cholesterol and amino acids
deficiency: weakness, slows wound healing, bleeding gums, scurvy The vitamin can be decreased by cigarette smoking, stressful injuries, stress and oral contraceptives. hypervitaminosis: excessive doses can cause kidney stones and break down red blood cells
Red pepper 1 red pepper - 148 g vit. C - 190% vit. A - 8% Calcium - 2% Iron - 2%
Strawberry 8 pieces - 147g vit. C - 160% vit. A -0% Calcium - 2% Iron - 4% Very good source of vit.c, fiber and folate.
Grapefruit 1/2 of grapefruit - 154g vit. C - 110% vit. A - 15% Calcium - 2% Iron - 0%
VITAMIN B COMPLEX Eight vitamins that make up the B Complex of vitamins: B1 - Thiamine B2 - Riboflavin B3 - Niacin B5 - Panthotenic acid B6 - Pyridoxine B7 Biotin B9 - Folate (folic acid) B12 (Cobalamin, cyanocobalamin)
Thiamin (Vitamin B1) sources: whole grains, nuts and meat, especially pork. White and brown flour and many breakfast cereals are usually fortified with thiamin. RDA: 1,5 mg for men, 1,1 mg for women function: Thiamin is needed to release energy from carbohydrate. It is involved in the normal function of the nervous system and the heart. deficiency: causes beri-beri (symptoms: weight loss, emotional disturbances, weakness and pain in the limbs, irregular heart rate...), a disorder of the nervous system, which occurs in communities where white rice is the main food eaten. A different type of thiamin deficiency affecting brain function is sometimes seen in alcoholics, where daily thiamin intake is low and absorption and utilisation of the vitamin is impaired. hypervitaminosis: general lack of toxicity
Riboflavin (Vitamin B2) sources: milk, eggs, fortified breakfast cereals, liver and green vegetables. RDA: 1,7 mg for men, 1,3 mg for women function: Riboflavin is required to release energy from protein, carbohydrate and fat. It is also involved in the transport and metabolism of iron in the body and is needed for the normal structure and function of mucous membranes and skin. deficiency: Although there is no specific deficiency disease, low intakes lead to dryness and cracking of the skin around the mouth and nose. hypervitaminosis: general lack of toxicity, excess riboflavin is excreted in the urine.
Niacin (nicotinic acid, B 3) sources: Niacin is found in most foods, although meat is the major source. It can also be made by the body from the amino acid tryptophan. RDA: 19 mg for men, 15 mg for women function: It is required for the release of energy from food, for the normal structure of the skin and mucous membranes and for normal functioning of the nervous system. deficiency: a disease called pellagra (symptoms: high sensitivity to sunlight, aggression, dermatitis, red skin lesions, insomnia...) Nicotinic acid is sometimes prescribed by doctors (as a drug) to treat high blood lipid levels, i.e. hyperlipidaemia (excess fat in the blood). hypervitaminosis: rare, headache, nausea, burning and itching skin
Pantothenic acid (Vitamin B 5) sources: beef and pork liver, lean meats, milk, eggs, legumes, whole grain products, most vegetables A recent study also suggests that gut bacteria in humans can generate pantothenic acid RDA: 4 7 mg function: Pantothenic acid is needed to form coenzyme-a (CoA), and is critical in the metabolism and synthesis of carbohydrates, proteins, and fats. deficiency: rare, fatigue, nausea, loss of appetite, mental depression hypervitaminosis: general lack of toxicity
Pyridoxine (Vitamin B6) Vitamin B6 comprising 3 forms pyridoxine, pyridoxal and pyridoxamine. sources: is found in a variety of foods: beef, fish and poultry are rich sources. It also occurs in eggs, whole-grains and some vegetables. RDA: 2 mg for men, 1,6 mg for women function: It is essential as a coenzym in protein metabolism, necesary for formation of hemoglobin and red blood cells, needed for glycogenolysis and gluconeogenesis. Together with folate and vitamin B12, vitamin B6 is required for maintenance of normal blood homocysteine levels. Raised homocysteine is a risk factor for cardiovascular disease. deficiency: a complication of cardiovascular disease, nerve damage, anemia hypervitaminosis: loss of nerve sensation,
Biotin (Vitamin B 7 or H) sources: meats, legumes, milk, egg yolk, whole grain products, most vegetables RDA: 300 µg function: It is a coenzyme in the metabolism of carbohydrates, fats, and protein. deficiency: rare, fatigue, nausea, skin rashes hypervitaminosis: general lack of toxicity Biotin supplements are often recommended as a natural product to counteract the problem of hair loss.
Folate (vitamin B 9) Folic acid is the synthetic form of the vitamin and the most stable. It is used in supplements and for food fortification. Various folates are found in both plant and animal foods. sources: liver, yeast extract, orange juice and green leafy vegetables. Various foods, e.g. breakfast cereals and bread may be fortified with folic acid. RDA: 200 µg for men, 180 µg for women function: Folate is essential for normal cell division and in the formation of blood cells. It is also needed for the normal structure of the nervous system and specifically in the development of the neural tube (which develops into the spine and skull) in the developing embryo. Together with vitamins B6 and B12, folate is involved with the maintenance of normal blood homocysteine levels. deficiency: megaloblastic anaemia, gastrointestinal disorders Increasing intakes of folate through supplements of folic acid, before conception and during the first twelve weeks of pregnancy, prevents the majority of neural tube defects (e.g. spina bifida) in babies. It is recommended that all women of childbearing age, and especially those planning a pregnancy and who are in the early stages of pregnancy, take a daily supplement of 400μg folic acid as it is difficult to achieve this amount of additional folate by diet alone. Women s diets typically provide about 250 μg folate/day. hypervitaminosis: may prevent of detection of pernicious anemia (caused by B 12 deficiency)
Cyanocobalamin (Vitamin B12) sources: Dietary intake is exclusively from animal sources, e.g. milk, meat and eggs (and fortified foods). Although some bacteria can make vitamin B12, it is probably not in a form that can be used by the body. Fortified breakfast cereals can be a useful source of this vitamin. RDA: 2 µg function: normal cell division and normal blood formation, for the normal structure and function of nerves. Together with folate and vitamin B6, it is required for the maintenance of normal blood homocysteine levels; raised blood homocysteine is a risk factor for cardiovascular disease. deficiency: Dietary deficiency is rare, although it is sometimes seen in vegans who obtain virtually no vitamin B12 in their diet. Deficiency is also caused by a lack of intrinsic factor - the substance needed for the absorption of vitamin B12. This leads to a type of pernicious anaemia in which red cells are enlarged (megaloblastic), and to neurological damage - paralysis. hypervitaminossis: general lack of toxicity