All About Vitamins
Vitamins
Vitamins serve crucial functions in almost all bodily processes (immune, hormonal and nervous systems) and must be obtained from food or supplements as our bodies are unable to make vitamins. There are thirteen vitamins classified as either water soluble (C and B complex) or fat soluble (A, D, E and K).
Fat Soluble Vitamins
Fat-soluble vitamins are absorbed, together with fat from the intestine, into the circulation. Any disease or disorder that affects the absorption of fat, such as coeliac disease, could lead to a deficiency of these vitamins. Once absorbed into the circulation these vitamins are carried to the liver where they are stored.
Vitamins A, D, E and K make up the fat soluble vitamins. Vitamins A, D and K are stored in the liver and vitamin E is distributed throughout the body's fatty tissues.
Water Soluble Vitamins
Water-soluble vitamins, such as Vitamin C and the B vitamins are stored in the body for only a brief period of time and are then excreted by the kidneys. The one exception to this is vitamin B12, which is stored in the liver. Water-soluble vitamins need to be taken daily.
Vitamin C (ascorbic acid) and the B complex group make up the nine water soluble vitamins. The B complex group comprises of vitamins:
- B6 (pyridoxine)
- B1 (thiamine)
- B2 (riboflavin)
- B12 (niacin, pantothenic acid, biotin, folic acid and cobalamin)
Vitamin sources, uses and deficiency problems
Vitamin A (fat-soluble)
- Sources: Dairy products, eggs, liver. Can be converted by the body from the beta-carotene found in green vegetables, carrots and liver.
- Uses: Maintains the health of the epithelium and acts on the retina's dark adaptation mechanism.
- Deficiency leads to: Keratinisation of the nasal and respiratory passage epithelium, night blindness
Vitamin B1 (thiamine) (water-soluble)
- Sources: Yeast, egg yolk, liver, wheatgerm, nuts, red meat and cereals
- Uses: Carbohydrate metabolism
- Deficiency leads to: Fatigue, irritability, loss of appetite; severe deficiency can lead to beri-beri
Vitamin B2 (riboflavin) (water-soluble)
- Sources: Dairy products, liver, vegetables, eggs, cereals, fruit, yeast
- Uses: Intracellular metabolism
- Deficiency leads to: Painful tongue and fissures to the corners of the mouth, chapped lips
Vitamin B12 (water-soluble)
- Sources: Liver, red meat, dairy products and fish
- Uses: Essential for manufacturing of genetic material in cells. Involved in the production of erythrocytes
- Deficiency leads to: pernicious anaemia
Vitamin C (ascorbic acid) (water-soluble)
- Sources: Green vegetables and fruit
- Uses: Essential for the maintenance of bones, teeth and gums, ligaments and blood vessels. It is also necessary for ensuring a normal immune response to infection
- Deficiency leads to: Scurvy
Vitamin D (fat-soluble)
- Sources: Fish liver oils, dairy produce. Vitamin D is formed in the skin when it is exposed to sunlight
- Uses: Has a role in the absorption of calcium, which is essential for the maintenance of healthy bones
- Deficiency leads to: Rickets
Vitamin E (fat-soluble)
- Sources: Pure vegetable oils; wheatgerm, wholemeal bread and cereals, egg yoke, nuts sunflower seeds
- Uses: Protects tissues against damage; promotes normal growth and development; helps in normal red blood cell formation
- Deficiency leads to: May cause muscular dystrophy
Vitamin K (fat-soluble)
- Sources: Green vegetables
- Uses: Used by the liver for the formation of prothrombin
- Deficiency leads to: Bleeding due to delayed clotting times caused by lack of clotting factors. Patients may show signs of bruising easily and have nosebleeds.
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