Ingredient Type: Vitamin
Also Known As: Pyridoxine hydrochloride, Pyridoxine, Pyridoxal-5-Phosphate
Vitamin B-6 is one of eight B Vitamins and an essential nutrient for all animals obtained only through the diet. Natural sources include cereal grains, legumes, vegetables (carrots, spinach, peas, and potatoes), milk, cheese, eggs, fish, liver, meat, and flour. It is involved in the process of making serotonin and norepinephrine, which are chemicals that transmit signals in the brain.
Vitamin B-6 is also involved in the formation of myelin, a protein layer that forms around nerve cells. Deficiency in adults may cause health problems affecting the nerves, skin, mucous membranes, and circulatory system.
Vitamin B6 is coenzyme. Enzymes are substances that speed up reactions. They do this to help the body perform a task, which can be anything from digesting food to keeping the liver functioning properly. A coenzyme is a molecule that works with the enzyme to aid it in carrying out its job. Without the coenzyme, the enzyme would be useless. As a coenzyme, vitamin B6 assists in a variety of tasks, including:
- The creation of heme, the iron-containing component of red blood cells;
- Making the hormone serotonin (the “feel good” hormone);
- Processing carbohydrates for energy;
- Keeping the nervous system working smoothly
Vitamin B6 is a member of the vitamin B family. It is present in many foods including cereal grains, legumes, vegetables, liver, meat, and eggs. In the body, vitamin B6 is required for amino acid metabolism. It is also involved in carbohydrate and lipid metabolism.
P5P is an active form of vitamin B6 that your body can easily utilize, often referred to as P5P for short. It is the active form of vitamin B6. In foods or most supplements, vitamin B6 is found in one of three forms: pyridoxine hydrochloride, pyridoxal, or pyridoxamine. Inside the body, these forms of B6 must be converted by the liver to the active form the body needs – P5P. Low rates of conversion from the inactive to the active form of vitamin B6 have been reported, especially in people with impaired liver function, celiac’s disease, older adults, and in children with autism. By consuming vitamin B6 in the active P5P form, conversion is no longer necessary, and the full benefits are available immediately after absorption.
Vitamin B6 was first described by Paul Gyorgy in 1934. He determined that dermatitis acrodynia, a skin disease that occurs in rats fed a diet devoid of vitamin B complex but still containing vitamin B1 and vitamin B2, could be treated by giving them a particular substance that Gyorgy called vitamin B6. By 1938, vitamin B6 was isolated, and it was first synthesized shortly thereafter. Initially, pure vitamin B6 was referred to as pyridoxine. In the mid-1950s it was determined that vitamin B6 actually occurs naturally in several forms: pyridoxine, pyridoxal, pyridoxamine, and the phosphate derivatives of these forms (1).
Vitamin B-6 is used in health supplements today to help with brain and nervous system function.
One commonly used purpose is to increase attention span in attention deficit-hyperactivity disorder (ADHD).
WHAT DOES SCIENCE TELL US?
Age-related cognitive impairment: One clinical trial shows that taking a combination of B vitamins for 24 months reduces cerebral atrophy in the gray matter regions associated with Alzheimer's disease, by up to seven-fold compared with placebo in elderly people with memory complaints. However, this protection does not occur in patients with the lowest average blood levels of homocysteine (17). Furthermore, other clinical research shows that taking vitamin B6 (pyridoxine) in combination with folic acid and vitamin B12 (cyanocobalamin) does not improve cognitive function in elderly patients (18).
Attention deficit-hyperactivity disorder (ADHD): Preliminary clinical research suggests that taking vitamin B6 (pyridoxine) orally, alone or in combination with high doses of other B vitamins, might help ADHD (19). However, research using megadose vitamin B6 (pyridoxine) in combination with other megadose vitamins seems to show no effect on ADHD symptoms (20).
Considered safe when used orally and appropriately it is deemed safe. Injectable vitamin B6 (pyridoxine) is an FDA-approved prescription product.
Orally or by injection, vitamin B6 (pyridoxine) can cause nausea, vomiting, abdominal pain, heartburn, loss of appetite, headache, paresthesia, somnolence, and decreased serum folic acid concentrations. It has also been linked to reports of skin and other allergic reactions, breast soreness or enlargement, and photosensitivity (13) Vitamin B6 (pyridoxine) can cause sensory neuropathy, which is related to daily dose and duration of intake. Doses exceeding 1000 mg daily or total doses of 1000 grams or more pose the most risk, although neuropathy can occur with lower daily or total doses as well (14). High-dose vitamin B6 (80 mg/day as pyridoxine) and vitamin B12 (20 micrograms/day) may result in intense erythema with nodules, papules, and pustules, possibly requiring treatment with systemic corticosteroids and topical therapy (16). There is some preliminary concern that long-term dietary vitamin B6 intake in small amounts ranging from 3.56-6.59 mg daily can increase the risk of developing ulcerative colitis (17).
Moderate interactions with prescriptions: Amiodarone, antihypertensive, levodopa, phenobarbital, phenytoin (22)
Interactions with Herbs and supplements: Theoretically may increase the risk of hypotension. examples: andrographis, casein peptides, cat's claw, coenzyme Q10, fish oil, L-arginine, lycium, stinging nettle, theanine and others. (21)
- McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
- Khoo SK, Munro C, Battistutta D. Evening primrose oil and treatment of premenstrual syndrome. Med J Aust 1990;153:189-92
- Woodside JV, Yarnell JW, McMaster D, et al. Effect of B-group vitamins and antioxidant vitamins on hyperhomocysteinemia: a double-blind, randomized, factorial-design, controlled trial. Am J Clin Nutr 1998;67:858-66
- Wyatt KM, Dimmock PW, Jones PW, Shaughn O'Brien PM. Efficacy of vitamin B6 in the treatment of premenstrual syndrome. BMJ 1999;318:1375-81
- Lonn E, Yusuf S, Dzavik V, et al. Effects of ramipril and vitamin E on atherosclerosis: the study to evaluate carotid ultrasound changes in patients treated with ramipril and vitamin E (SECURE). Circulation 2001;103:919-25
- Parry GJ, Bredesen DE. Sensory neuropathy with low-dose pyridoxine. Neurology 1985;35:1466-8
- Harel Z, Biro FM, Kottenhahn RK, Rosenthal SL. Supplementation with omega-3 polyunsaturated fatty acids in the management of dysmenorrhea in adolescents. Am J Obstet Gynecol 1996;174:1335-8
- Bendich A, Cohen M. Vitamin B6 safety issues. Ann N Y Acad Sci 1990;585:321-30
- Smith GP, Rudge PJ, Peters TJ. Biochemical studies of pyridoxal and pyridoxal phosphate status and therapeutic trial of pyridoxine in patients with carpal tunnel syndrome. Ann Neurol 1984;15:104-7.
- Franzblau A, Rock CL, Werner RA, et al. The relationship of vitamin B6 status to median nerve function and carpal tunnel syndrome among active industrial workers. J Occup Environ Med 1996;38:485-91.
- Kotani, N., Oyama, T., Sakai, I., Hashimoto, H., Muraoka, M., Ogawa, Y., and Matsuki, A. Analgesic effect of a herbal medicine for treatment of primary dysmenorrhea--a double-blind study. Am.J Chin Med 1997;25(2):205-212
- Lauritzen CH, Reuter HD, Repges R, Bohnert K, and Schmidt U. Treatment of premenstrual tension syndrome with Vitex agnus castus. Controlled, double-blind study versus pyridoxine. Phytomed 1997;4(3):183-189
- Bendich A, Cohen M. Vitamin B6 safety issues. Ann N Y Acad Sci 1990;585:321-30
- Jansen T, Romiti R, Kreuter A, Altmeyer P. Rosacea fulminans triggered by high-dose vitamins B6 and B12. J Eur Acad Dermatol Venereol 2001;15:484-5
- Geerling BJ, Dagnelie PC, Badart-Smook A, et al. Diet as a risk factor for the development of ulcerative colitis. Am J Gastroenterol 2000;95:1008-13
- Douaud G, Refsum H, de Jager CA, et al. Preventing Alzheimer's disease-related gray matter atrophy by B-vitamin treatment. Proc Natl Acad Sci U S A 2013;110(23):9523-8.
- Ford, A. H. and Almeida, O. P. Effect of homocysteine lowering treatment on cognitive function: a systematic review and meta-analysis of randomized controlled trials. J.Alzheimers.Dis. 2012;29(1):133-149.
- Brenner A. The effects of megadoses of selected B complex vitamins on children with hyperkinesis: controlled studies with long-term follow-up. J Learn Disabil 1982;15:258-64
- Haslam RH, Dalby JT, Rademaker AW. Effects of megavitamin therapy on children with attention deficit disorders. Pediatrics 1984;74:103-11
- Lal, K. J., Dakshinamurti, K., and Thliveris, J. The effect of vitamin B6 on the systolic blood pressure of rats in various animal models of hypertension. J Hypertens. 1996;14(3):355-363
- Butterworth CE. Interactions of nutrients with oral contraceptives and other drugs J Am Diet Assoc 1973;62:510-4.
See the National Institutes of Health Office of Dietary Supplements entry for vitamin B6, the MedlinePlus entry for pyridoxine, the RXList entry for pyridoxine, the Michigan Medicine Health Library entry for vitamin B6, or the Examine.com entry for vitamin B6 for more information.