Vitamin B6 is a member of the water-soluble B-vitamins and is also known as pyridoxine, pyridoxal and pyridoxamine. All three of these forms are converted in the body to the active forms, pyridoxal phosphate (PLP). PLP is very important in the metabolism of amino acids such as the removal of amine groups and the generation of semi-essential amino acids from non-essential ones. Of importance to athletes, the release of glucose from glycogen heavily relies on the actions of PLP. PLP is also involved in the synthesis of lecithin, hemoglobin and nucleic acids. Vitamin B6 has roles in immune function and steroid hormone activity. Unlike most water-soluble vitamins, vitamin B6 is actually stored in high quantities in skeletal muscle.
Alcohol interferes with vitamin B6 and actively promotes its destruction and excretion from the body. Vitamin B6 is an essential dietary component and deficiency can result in symptoms such as weakness, anemia, kidney stones, irritability and insomnia. Unlike most of the B-vitamins, vitamin B6 has been shown to have some degree of toxicity – likely due to its storage in muscle tissue. Large doses of B6 can cause irreversible nerve damage but in many cases, the nervous symptoms reverse after supplementation is stopped. Other side effects include bloating, depression, fatigue, numbness and headaches. Side effects and toxicity have only been noted with persons taking vitamin B6 supplements, not food sources. Vitamin B6 is found in high quantities in beef liver, bananas, spinach, potatoes and watermelon among others.