Definition:

Vitamin B6 is a water-soluble vitamin that was first isolated in the 1930s. Vitamin B6 refers to six common forms, namely pyridoxal, pyridoxine (pyridoxal), pyridoxamine, and their phosphorylated forms. The phosphate ester derivative pyridoxal 5′-phosphate (PLP) is the bioactive coenzyme form involved in over 4% of all enzymatic reactions.

• Vitamin B6 and its derivative pyridoxal 5′-phosphate (PLP) are essential to over 100 enzymes mostly involved in protein metabolism.
• High levels of circulating homocysteine are associated with an increased risk of cardiovascular disease. Randomized controlled trials have demonstrated that supplementation with B vitamins, including vitamin B6, could effectively reduce homocysteine levels. However, homocysteine lowering by B vitamins has failed to lower the risk of adverse cardiovascular outcomes in high-risk individuals.
• Growing evidence from experimental and clinical studies suggests that systemic inflammation underlying most chronic diseases may impair vitamin B6 metabolism.
• Although supplementation with vitamin B6 and other B vitamins has not been associated with improved cognitive performance or delayed cognitive deterioration in the elderly, recent studies suggest that vitamin B6 might help reduce the risk of late-life depression.
• Pharmacologic doses of vitamin B6 are used to treat seizures in rare inborn errors of vitamin B6 metabolism. Also, randomized controlled trials support the use of vitamin B6 to treat morning sickness in pregnant women and suggest a possible benefit in the management of premenstrual syndrome and carpal tunnel syndrome.
• Vitamin B6 is found in a variety of foods, including fish, poultry, nuts, legumes, potatoes, and bananas.
• Several medications, including anti-tuberculosis drugs, anti-parkinsonians, nonsteroidal anti-inflammatory drugs, and oral contraceptives, may interfere with vitamin B6 metabolism.

Deficiency Symptoms:

Manifestations of vitamin B6 deficiency may include nervousness, depression, insomnia, irritability, confusion, glossitis, stomatitis, abdominal pain, weakness, seizures, sideroblastic anemia, and impaired immune function.

Dosage and administration

• The usual dosage range of vitamin B6 for the prevention and treatment of various conditions is 10–200 mg/day.
• Larger doses have been used in some cases, such as in the treatment of certain psychiatric conditions and some vitamin B6-dependency syndromes.
• As with any nutrient that has the potential for toxicity, the lowest effective dose should be used. As noted above, patients taking more than 200 mg/day of vitamin B6 should be monitored for the development of neurotoxicity.