V i t a m i n B 6
Vitamin B6' s (Pyridoxine) primary role is to act as a coenzyme to many other enzymes in the body that are involved predominantly in metabolism.
This role is performed by the active form, pyridoxal phosphate, which is converted from the other natural forms found in food: pyridoxal, pyridoxine and pyridoxamine.
Much of the body's chemistry depends upon enzymes. Enzymes are proteins that help chemical reactions take place. Because vitamin B6 is involved with more than 100 enzymatic reactions, its function in the body is diverse and far-reaching. Vitamin B6 can be regarded as an essential part of the formation of virtually all new cells in the body.
Vitamin B6 is involved in the sythesis of several neurotransmitters, chemicals that carry signals from one nerve cell to another. It is needed for normal brain development and function, and helps the body make the hormone serotonin, which influence mood, and melatonin, which helps regulate the body clock. The liver is the site for vitamin B6 metabolism.
Pyridoxine lowers blood pressure and blood cholesterol levels and keeps blood platelets from sticking together.
Along with vitamins B12 and B9 (folic acid), vitamin B6 helps control levels of homocysteine in the blood. Your body also needs B6 in order to absorb vitamin B12 and to make red blood cells and cells of the immune system. All of these properties work to keep heart disease at bay.
Vitamin B6 has long been publicized as a cure for premenstrual syndrome (PMS). Because of pyridoxine's role in serotonin and other neurotransmitter production, supplementation often helps depressed people feel better, and their moods improve significantly. It may also help improve memory in older adults.
Cooking, storage, and processing losses of vitamin B6 vary and in some foods may be more than 50%, depending on the form of vitamin present in the food.
Plant foods lose the least during processing, as they contain mostly pyridoxine, which is far more stable than the pyridoxal or pyridoxamine found in animal foods.
1.7 mg RDA - 100 mg UL
RDA (recommanded dietary allowances) per day 
UL (upper intake level) per day 
 Dietary Reference Intakes: Vitamins.
The National Academies, 2001