Vitamins

Vitamin

Functions

Sources

Signs of
Deficiencies

Signs of
Excessive Intake

A
(Retinol)

See also
Vitamin A in the news.

• Essential for growth
• Vision in dim light
• Maintenance of soft mucous tissue

• Milk products
• Egg yolk
• Liver

Can be formed in the body from its precursor (beta-carotene), found in:

• Cabbage
• Carrots
• Green vegetables
• Lettuce
• Orange/yellow vegetables
• Yellow/red fruits.

Early indications of excess vitamin A can include dry skin and itching.
Vitamin A can be stored in the body in such large quantities that it can become toxic. Symptoms may include: dizziness, nausea, headaches and vomiting.

B1 (Thiamin, Aneurine)

See also
Vitamin B in the news.

• Formation of the enzyme thiamin pyrophosphate
• Promotes normal metabolism, appetite, digestion, and growth
• Brain development and function.

• Beans
• Cereals
• Meat
• Nuts
• Peas
• Potatoes
• Yeast

Excessive doses (possibly by injection) may lead to toxic symptoms such as:

• Allergic reactions
• Disturbance of heart beat
• Nervousness
• Shaking & Swellings
  

B2
(Riboflavin)

• Production of acetylcholine, noradrenalin, serotonin (neurotransmitters essential to the brain)
• Release of energy from carbohydrates
• Synthesis of arachidonic acid, linoleic acid and linolenic acid (essential fatty a class="related_item"cids)
• Tissue respiration.

• Cheese
• Eggs
• Fish
• Liver
• Milk
• Pulses

Deficiency can lead to:

Overdose is unlikely but extremely large doses are associated with numbness and itching.

• Ariboflavinosis
• Dizziness
• Eczema
• Insomnia
• Oversensitivity to light
• Scaly Scalp

B6
(Pyridoxine)

Many functions including:

Many foods including:

Rare, but can lead to:

Excessive intake can lead to poisoning and damage to the central and peripheral nervous systems, especially the sense of touch.

• Maintaining healthy skin and nerves
• Formation of red blood cells
• Formation of hormones essential for functioning of the brain
• Synthesis & breakdown of amino acids
• Resistance to disease
• Signs of premature ageing.

• Fish
• Green vegetables
• Meat
• Milk
• Liver
• Whole-grain cereals

• Loss of appetite
• Anaemia
• Fatigue
• Nervousness
• Insomnia
• Memory problems
• Menstrual problems

B9
(Folic Acid)

• Synthesis of nucleic acids
• Pre-conception & in early pregnancy folic acid is thought to help prevent neural tube defects and other congenital foetal malformations.

• Green leafy vegetables (such as spinach)
• Kidneys
• Liver
• Nuts
• Whole-grains
• Yeast extract

• Megaloblastic anaemia (includes several types of anaemia)
• Apathy / Depression
• Dizziness
• Dull grey-looking skin.

B12
(Cyanocobalamin)

• Synthesis of nucleic acids
• Maintenance of myelin in the nervous system
• Correct functioning of Folic Acid.

• Brewers Yeast
• Dairy products
• Eggs
• Fish
• Liver
• Meat

• Affects most body tissues, especially those containing rapidly dividing cells
• Pernicious anaemia
• Degeneration of the nervous system (incl. loss of sensation and poor co-ordination)
• Tongue infections

C
(Ascorbic Acid)

See also
Vitamin C in the news.

• Antioxidant Properties
• Maintaining healthy connective tissues
• Integrity of cell walls
• Synthesis of collagen
• Improves resistance to infections
• Promotes healthy function of phagocytes (a type of white blood cell)
• May help to reduce allergic reactions (by inhibiting the action of histamine).

• Citrus Fruits
• Potatoes
• Vegetables

• Sudden high intake of vitamin C can cause diarrhoea.
• Very high dosage can lead to stomach problems in some people.

D

See also
Vitamin D in the news.

• Absorption of calcium and phosphorous (from the intestine & deposition of them in the bone).
• Regulation of the permeability of cell membranes.

• Liver
  
• Fish oils
• Ergocalciferol
  (Vitamin D2)
  from plant sources
• Cholecalciferol
  (Vitamin D3)
  is produced by the action of sunlight on
  7-dehydrocholesterol, which is in the skin.

Deficiency may be due to poor diet or to insufficient sunlight and can lead to:

• Over-calcification of the bones and teeth
• Formation of calculus stones in the kidneys and other organs
• Hardening of arteries.
• In cases of extreme over-dose, vitamin D may lead to poisioning. Symptoms may include: General discomfort, itchy eyes and skin, extreme thirst,
  diarrhoea.

• Decalcified bones
• Rickets (in children)
• Problems in dental development (in children)
• Osteomalacia (in adults)
• Muscle weakness and cramps
• Osteoporosis - if deficiency over extended period of time.

E
(Tocopherols and Tocotrienols)

See also
Vitamin E in the news.

• Antioxidant properties
• Muscle Development
• Production of red blood cells
• Reproductive functions.
  

• Butter
• Corn and peanut oils
• Eggs
• Soya beans
• Vegetable oils
• Wheat germ
• Wholemeal Cereals.

Some vitamin E can be safely stored in the body but excessive doses may result in stomach problems and diarrhoea.

K

• Formation of prothrombin by the liver - for blood clotting.

• Fish
• Green leafy vegetables
• Meat
• Molasses
• Nuts
• Seaweed
• Also synthesized by bacteria in the large intestines.

Deficiency may lead to osteoporosis

Some people with liver diseases cannot tolerate supplements of vitamin K.