Vitamin B-6 is a water-soluble organic compound that is particularly abundant in cereal grains, meats, nuts, and some fruits and vegetables. Large doses of vitamin B-6 have often been recommended for treatment of carpal tunnel syndrome, although scientific research does not indicate its efficacy.

In humans, vitamin B-6 is essential for various functions in the body, such as red blood cell and protein metabolism. A form of vitamin B-6, pyridoxine, was first isolated in 1938 and was synthesized the following year. Subsequently, two other types of the vitamin, pyridoxal and pyridoxamine, were discovered. The three forms of vitamin B-6 apparently are equally effective in the nutrition of animals, but pyridoxal and pyridoxamine are much more active than pyridoxine in microorganisms.

The adult human requires approximately 2.0 to 2.2 mg of vitamin B-6 each day. Although there is not a particular disease that is solely attributable to a deficiency of vitamin B-6, a shortage can cause health problems, such as irregular glucose levels and poor immunity. Good health can also be hindered by excessively large intakes of vitamin B-6 and the Institute of Medicine has set the upper tolerable daily limit at 100 mg for adults.