Quest Vitamins LTD,
Vitamin B6 is a well-known member of the water-soluble B vitamins. Besides pyridoxine, two other variations on B6 exist - namely pyridoxal and pyridoxamine. All three forms exist routinely in animal and plant foods and have equal vitamin B6 activity.
Vitamin B6 is fairly resistant to heat but may leach out into water and is also lost by exposure to alkalis or ultraviolet light.
Vitamin B6 is rapidly converted in the body to the coenzymes pyridoxal phosphate and pyridoxamine phosphate. These coenzymes play an essential role in protein metabolism and also function in energy production, fat metabolism, central nervous system activity and haemoglobin production.
The administration of a vitamin B6 antagonist to the diet of human volunteers produced symptoms of seborrhoea (oily Skin with crusts and scales) around the Eyes, nose and mouth. There was also a lowering of white blood cell count and a loss of ability to convert tryptophan to nicotinic acid. A type of Anaemia was also noted.
Upper safe level for daily supplementation = 200mg
Recommended Daily Allowance = 2mg
Individuals with high intakes of protein will need more vitamin B6 in the diet.
The Pill and HRT:
Drinkers and Smokers:
2-7g vitamin B6 daily may bring about the development of sensory neuropathy (numbness and tingling of nerves in the extremities). Such symptoms have also been reported in women taking as low as 50mg daily, but these reports have since largely been discredited. All cases of peripheral neuropathy disappeared within six months on withdrawal of the vitamin.
Phenytoin and Phenobarbitone:
It is usually recognised that B vitamins are best taken together for most general purposes. However, there is no detriment in taking vitamin B6 singly for a specific reason.
The main sources of vitamin B6 in the diet are potatoes and other vegetables, milk and meat.
1. Villegas Salas E. et al, Effect of vitamin B6 on the side effects of a low-dose combined oral contraceptive. Contraception, ,55;4:245-248, 1997.