Vitamin B 6
(See also Overview of Vitamins.)
Vitamin B6 (pyridoxine) is essential for the processing (metabolism) of carbohydrates, amino acids, and fats (lipids), as well as for normal nerve function and for the formation of red blood cells. It also helps keep the skin healthy.
Good sources of vitamin B6 include dried yeast, liver, other organ meats, whole-grain cereals, fish, and legumes.
Many foods contain vitamin B6, but extensive processing can remove the vitamin.
People may have seizures, a scaly rash, a red tongue, cracks in the corners of the mouth, or a pins-and-needles sensation in the hands and feet.
The diagnosis is based on symptoms, the presence of possible causes, and response to vitamin B6 supplements.
Vitamin B6 supplements, taken by mouth, can correct the deficiency.
Because vitamin B6 is present in many foods, the deficiency rarely results from inadequate intake. However, such a deficiency can occur because extensive processing can remove vitamin B6 from foods.
Vitamin B6 deficiency often results from
Impaired absorption of food (malabsorption disorders)
Use of drugs that deplete vitamin B6 stored in the body
These drugs include anticonvulsants (used to treat seizure disorders), the antibiotic isoniazid, hydralazine (used to treat high blood pressure), corticosteroids, and penicillamine (used to treat such disorders as rheumatoid arthritis and Wilson disease).
In adults, vitamin B6 deficiency can cause inflammation of the skin (dermatitis) and a red, greasy, scaly rash. The hands and feet may feel numb and prickling—like pins and needles. The tongue may become sore and red, and cracks may form in the corners of the mouth. People may become confused, irritable, and depressed. They may have seizures.
Rarely, vitamin B6 deficiency causes seizures in infants. Anticonvulsants may be ineffective in treating these seizures in infants.
Because vitamin B6 is needed to form red blood cells, deficiency can cause anemia.
The diagnosis of vitamin B6 deficiency is based on symptoms, the presence of conditions that can cause the deficiency, and response to vitamin B6 supplements.
Blood tests may be done, but no routine blood test can clearly confirm the diagnosis.
Vitamin B6 in very high doses may be prescribed for such disorders as carpal tunnel syndrome, premenstrual syndrome, and nerve damage (neuropathy), although there is little evidence of benefit.
Taking such high doses of vitamin B6 may cause pain and numbness in the feet and legs. People may be unable to tell where their arms and legs are (position sense) and to feel vibrations. Thus, walking becomes difficult.
The diagnosis of vitamin B6 toxicity is based on symptoms and a history of taking high doses of vitamin B6.
Treatment of vitamin B6 toxicity involves stopping vitamin B6 supplements. Recovery from this disorder may be slow, and people may continue to have some difficulty walking.