Pyridoxine is absorbed readily from the small intestine and used throughout the body in a multitude of functions. Fasting and reducing diets usually deplete the vitamin B6 supply unless it is supplemented. Usually within eight hours, much of the excess is excreted through the urine; some B6 is stored in muscle. It is also produced by the intestinal bacteria.

Sources: Vitamin B6 in its several forms is widely available in nature, though not many foods have very high amounts. Since it is lost in cooking and in the refining or processing of foods, it is not the easiest B vitamin to obtain in sufficient amounts from the diet, especially if we eat much processed food, as it is not one of the vitamins replaced in "enriched" flour products such as cereals and pastries.

The best sources of vitamin B6 are meats, particularly organ meats, such as liver, and the whole grains, especially wheat. Wheat germ is one of the richest sources. Besides meat, good protein sources of B6 include fish, poultry, egg yolk, soybeans and other dried beans, peanuts, and walnuts. Vegetable and fruit sources include bananas, prunes, potatoes, cauliflower, cabbage, and avocados. As examples of how easily vitamin B6 is lost in the processing of food, raw sugar cane has a good amount, while refined sugar has none; whole wheat flour contains nearly 0.5 mg. of pyridoxine (wheat germ and wheat flakes have much more), while refined wheat flour has almost none, and even whole wheat bread has lost nearly all of its vitamin B6.

Functions: Pyridoxine and its coenzyme form, pyridoxal-5-phosphate, have a wide variety of metabolic functions in the body, especially in amino acid metabolism and in the central nervous system, where it supports production of gamma-aminobutyric acid (GABA). Many reactions, including the conversion of tryptophan to niacin and arachidonic acid to prostaglandin E2 require vitamin B6. The pyridoxal group is important in the utilization of all food sources for energy and in facilitating the release of glycogen (stored energy) from the liver and muscles. It helps as well in antibody and red blood cell production (hemoglobin synthesis) and in the synthesis and functioning of both DNA and RNA. By helping maintain the balance of sodium and potassium in the body, vitamin B6 aids fluid balance regulation and the electrical functioning of the nerves, heart, and musculoskeletal system; B6 is needed to help maintain a normal intracellular magnesium level, which is also important for these functions. The neurotransmitters norepinephrine and acetylcholine and the allergy regulator histamine are all very important body chemicals that depend on pyridoxal-5-phosphate in their metabolism. Also, the brain needs it to convert tryptophan to serotonin, another important antidepressant neurotransmitter.