Vitamin B6

Introduction

Pyridoxine is a water soluble vitamin that is instrumental in more than 100 enzyme reactions in the body. These activities are mostly related to the metabolism of amino acids and proteins.

The best sources of pyridoxine are brewer’s yeast, wheat germ, organ meats (especially liver), peanuts, legumes, potatoes and bananas. Bacteria in the human intestinal tract also synthesize vitamin B₆.

Dosage Info

Dosage Range

Not available

Most Common Dosage

20mg daily.

Dosage Forms

Tablets, capsules, liquids, liposomal sprays, and effervescent tablets.

Interactions and Depletions

Interactions

• levodopa

Depletions

• Antibiotics
• Estrogen and estrogen-like medications
• hydralazine
• Loop diuretics
• isoniazid
• penicillamine
• phenelzine
• theophylline

Reported Uses

Vitamin B₆ deficiency is one of the most common nutritional deficiencies. Much of this is due to the fact that a lot of vitamin B₆ is lost during cooking and food processing. A U.S. Department of Agriculture study reported that 80 percent of Americans consume less than the recommended dietary allowance (RDA) for pyridoxine. (1)

Adequate pyridoxine is important because it is involved in the production of hemoglobin in red blood cells and neurotransmitters like serotonin, which plays a part in regulating our moods and preventing depression. (2) , (3) It is also involved in energy production in the body, as well as the metabolism of homocysteine, the amino acid that is a risk factor for atherosclerosis. (4) , (5) When used with vitamin B12 and folic acid, studies have shown that it can decrease homocysteine levels. (6) Decreased vitamin B6 levels seemed to indicate a greater risk for coronary artery disease. (7) Dietary supplementation with the B-vitamins prevented hyperhomocysteinemia but did not prevent the development of vascular dysfunction or atherosclerotic lesions. (8)

Other studies involving hundreds of patients who had undergone successful coronary angioplasty have evaluated these individuals following six months of therapy on vitamin B6, vitamin B12 and folic acid, comparing the results to patients on placebo. After one year, the patients on the vitamin therapy had lower rates of related cardiovascular events including heart attacks and repeated angioplasty. (9) , (10)

There is a wide range of clinical applications for pyridoxine. Patients with rheumatoid arthritis have also been found to be deficient in vitamin B₆ and supplementation may be beneficial. (11) Asthmatics may experience fewer and less severe attacks when taking pyridoxine. (12) Studies have shown cognitive skills such as knowing, thinking, learning and judging can be impaired in older adults with low levels of certain B vitamins. Supplementation with folate, vitamin B12 and vitamin B6 has been effective in enhancing cognitive performance in older adults. (13) In fact, one study in older adults noted that subjects with low levels of vitamin B12 or folate had twice the risk of developing Alzheimer’s disease. (14)

Pyridoxine is also an important treatment for pyridoxine-dependent epilepsy. (15) , (16) It may even treat some symptoms of autism. (17) It may ease some of the nerve-related problems (neuropathies) that frequently develop in diabetic patients. (18)

Pyridoxine has been used to support female health as well. Studies suggest that it can reduce the severity and frequency of vomiting episodes during pregnancy. (19) It may also ease PMS symptoms.

Pyridoxine is required for the metabolism of monosodium glutamate (MSG). People who are sensitive to this common food additive are said to suffer from “Chinese restaurant syndrome.” In these individuals, supplementation with vitamin B6 often prevents or substantially reduces the severity of symptoms when they ingest MSG. (20) , (21)

Toxicities & Precautions

Introduction

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General

This dietary supplement is considered safe when used in accordance with proper dosing guidelines.

Side Effects

Occasional side effects reported with large doses (1g to 6g) of this dietary supplement include neurological toxicities. (22) , (23) Symptoms associated with neurological toxicities include tingling in the hands and feet, decreased muscle coordination, and a stumbling gait. It may be necessary to reduce the dose of this dietary supplement. Tell your doctor if these side effects become severe or do not go away.

Pregnancy / Breast Feeding

To date, the medical literature has not reported any adverse effects related to fetal development during pregnancy or to infants who are breast-fed. Proper nutrition is essential during pregnancy for the healthy development of the fetus. Numerous vitamins and minerals are a vital part of proper nutrition. If you are pregnant, think you might be pregnant, trying to get pregnant, or breast-feeding an infant, talk to your healthcare professional about supplementing your diet with appropriate vitamins and minerals.

Age Limitations

To date, the medical literature has not reported any adverse effects specifically related to the use of this dietary supplement in children. Vitamins and minerals are an essential part of proper growth and development. Talk to your healthcare professional about the appropriate use of vitamins and minerals in children. Do not use any vitamin or mineral in children under 2 years of age unless first discussed with your healthcare professional.

References

1. Pao EM, Mickle SJ. Problem Nutrients in the United States. Food Technology. 1981;35:58-62.
2. Adams PW, et al. Effect of Pyridoxine Hydrochloride (Vitamin B6) upon Depression Associated with Oral Contraception. Lancet. Apr1973;1(7809):899-904.
3. View Abstract: Bernstein AL. Vitamin B6 in clinical neurology. Ann NY Acad Sci. 1990;585:250-60.
4. View Abstract: Brattstrom L, et al. Impaired Homocysteine Metabolism in Early-onset Cerebral and Peripheral Occlusive Arterial Disease. Effects of Pyridoxine and Folic Acid Treatment. Atherosclerosis. Feb1990;81(1):51-60.
5. View Abstract: McKinley MC, McNulty H, McPartlin J, et al. Low-dose vitamin B-6 effectively lowers fasting plasma homocysteine in healthy elderly persons who are folate and riboflavin replete. Am J Clin Nutr. Apr2001;73(4):759-64.
6. View Abstract: Woodside JV, Yarnell JW, McMaster D, Young IS, Harmon DL, McCrum EE, et al. Effect of B-group vitamins and antioxidant vitamins on hyperhomocysteinemia: a double-blind, randomized, factorial-design, controlled trial. Am J Clin Nutr. May1998;67(5):858-66.
7. View Abstract: Friso S, Girelli D, Martinelli N, et al. Low plasma vitamin B-6 concentrations and modulation of coronary artery disease risk. Am J Clin Nutr. Jun2004;79(6):992-8.
8. View Abstract: Lentz SR, Piegors DJ, Malinow MR, Heistad DD. Supplementation of atherogenic diet with B vitamins does not prevent atherosclerosis or vascular dysfunction in monkeys. Circulation. Feb2001;103(7):1006-11.
9. View Abstract: Schnyder G, Roffi M, Pin R, Flammer Y, Lange H, Eberli FR, et al. Decreased rate of coronary restenosis after lowering of plasma homocysteine levels. N Engl J Med. Nov2001:345(22):1593-600.
10. View Abstract: Schnyder G, Roffi M, Flammer Y, Pin R, Hess OM. Effect of homocysteine-lowering therapy with folic Acid, vitamin B12, and vitamin b6 on clinical outcome after percutaneous coronary intervention: the swiss heart study: a randomized controlled trial. JAMA. Aug2002;288(8):973-9.
11. View Abstract: Kremer JM, et al. Nutrient Intake of Patients with Rheumatoid Arthritis is Deficient in Pyridoxine, Zinc, Copper, and Magnesium. J Rheumatol. Jun1996;23(6):990-94.
12. View Abstract: Reynolds RD, Natta CL. Depressed Plasma Pyridoxal Phosphate Concentrations in Adult Asthmatics. Am J Clin Nut. 1985;41:684-688.
13. View Abstract: Calvaresi E, Bryan J. B vitamins, cognition, and aging: a review. J Gerontol B Psychol Sci Soc Sci. Nov2001;56(6):P327-39.
14. View Abstract: Wang HX, Wahlin A, Basun H, Fastbom J, Winblad B, Fratiglioni L. Vitamin B(12) and folate in relation to the development of Alzheimer’s disease. Neurology. May2001;56(9):1188-94.
15. View Abstract: Crowell GF, et al. Pyridoxine-dependent Seizures. Am Fam Physician. Mar1983;27(3):183-87.
16. View Abstract: Goto T, et al. CSF glutamate/GABA concentrations in pyridoxine-dependent seizures: etiology of pyridoxine-dependent seizures and the mechanisms of pyridoxine action in seizure control. Brain Dev. Mar2000;23(1):24-9.
17. View Abstract: Rimland B, et al. The Effect of High Doses of Vitamin B6 on Autistic Children: A Double-blind Crossover Study. Am J Psychiatry. Apr1978;135(4):472-75.
18. Jones CL, et al. Pyridoxine Deficiency: A New Factor in Diabetic Neuropathy. J Am Podiatry Assoc. Sep1978;68(9):646-53.
19. View Abstract: Vutyavanich T, et al. Pyridoxine for Nausea and Vomiting of Pregnancy: A Randomized, Double-blind, Placebo-controlled Trial. Am J Obstet Gynecol. Sep1995;173(3 Pt 1):881-84.
20. View Abstract: Brush MG, et al. Pyridoxine in the Treatment of Premenstrual Syndrome: A Retrospective Survey in 630 Patients. Br J Clin Pract. Nov1988;42(11):448-52.
21. View Abstract: Folkers K, et al. The Biochemistry of Vitamin B6 is Basic to the Cause of the Chinese Restaurant Syndrome. Hoppe Seylers Z Physiol Chem. Mar1984;365(3):405-14.
22. View Abstract: Berger AR, Schaumburg HH, Schroeder C, Apfel S, Reynolds R. Dose response, coasting, and differential fiber vulnerability in human toxic neuropathy: a prospective study of pyridoxine neurotoxicity. Neurology. Jul1992;42(7):1367-1370.
23. View Abstract: Wyatt KM, Dimmock PW, Jones PW, O’Brien PMS. Efficacy of vitamin B-6 in the treatment of premenstrual syndrome: systematic review. BMJ. May1999;318:1375-1381.