Pyridoxine and Related Compounds - Vitamin B6

The Fat Soluble Vitamins · Vitamin A · Vitamin D · Vitamin E · Vitamin K The Water Soluble Vitamins · The B-Group Vitamins · Thiamine - Vitamin B1 · Riboflavin-Vitamin B2 · Pantothenic Acid - Vitamin B3 · Biotin - Vitamin B4 · Nicotinic Acid (Niacin) - Vitamin B5 · Pyridoxine - Vitamin B6 · Cyanocobalamin - Vitamin B12 · Ascorbic Acid - Vitamin C

Vitamin B6 consists of three closely related chemical compounds - pyridoxine, pyridoxal and pyridoxamine with similar physiological actions.

Physiological Action
Pyriodoxial phosphate is the coenzyme of the enzyme transaminase which plays a decisive part in the metabolism of the amino acids.

Pyridoxine is needed for the normal metabolism of tryptophan to nicotinic acids.  In the absence of an adequate supply for the vitamin, tryptophan is converted to an abnormal metabolite and excreted by the kidneys.  Pyridoxine also has a role in the metabolism of nervous tissue.

Deficiency
Occurs in infants characterised by increased irritability and convulsions.  The symptoms are promptly relieved by pyridoxine in adequate amounts, 10 mg or more daily.

Dietary Sources
The vitamin is widely distributed both in plant and animal tissues, which perhaps reflects it's importance in the metabolism of every kind of cell.  Meat, liver, vegetables and the bran of cereal grains are all good sources.

Recommended Minimum Dietary Intakes

• Infants 0.3-0.5 milligrams
• Children 0.6-2.2 milligrams
• Adult men 1.0-1.9 milligrams
• Adult women 0.8-1.4 milligrams
• Pregnancy 1.0-1.5 milligrams
• Lactation 1.6-2.2 milligrams