B-6 Pyridoxine
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B-6 (Pyridoxine) has been disappointing to date as a supplement.  A standard dosage is in multivitamins, but most individual supplements contain much higher doses.  It can also be obtained in a healthy diet. A recent large-scale study of patients after having stents placed in their coronary heart arteries because of blockage found that those on B-6 actually did worse than those on placebos.  B-12 and folate were also involved, but these have much more research and do not appear harmful.  B-6 is toxic in very high doses, e.g. 500 mg/d, and maybe even at lower levels.  I would hold off on pyridoxine supplements until more research is available.

Angioplasty Helped by Folate, B12, B6 in DB: 553 angioplasty Swiss DB PC with one group folate 1 g/d, B12 400 microg/d, B6 10 mg/d. Fewer deaths and infarctions in vitamin group. Homocysteine-lowering therapy with folic acid, vitamin B(12), and vitamin B(6) significantly decreases the incidence of major adverse events after percutaneous coronary intervention. Effect of homocysteine-lowering therapy with folic acid, vitamin B(12), and vitamin B(6) on clinical outcome after percutaneous coronary intervention: the Swiss Heart study: a randomized controlled trial. JAMA 2002 Aug 28;288(8):973-9 Schnyder G, Roffi M, Flammer Y, Pin R, Hess OM.

Autism: B-6 & Magnesium No Benefit: In a DB PC 10 week 12 patient study, there were no benefits detected. High-dose pyridoxine and magnesium administration in children with autistic disorder: an absence of salutary effects in a double-blind, placebo-controlled study. Findling RL, Maxwell K, Scotese-Wojtila L, Huang J, Yamashita T, Wiznitzer M. J Autism Dev Disord 1997 Aug;27(4):467-78

Cardiovascular: B-6, B-12, and Folate Bad for Coronary Stenting: 636 patients who had undergone successful coronary stenting were randomly assigned to receive 1 mg of folic acid, 5 mg of vitamin B6, and 1 mg of vitamin B12 intravenously, followed by daily oral doses of 1.2 mg of folic acid, 48 mg of vitamin B6, and 60 microg of vitamin B12 for six months, or placebo. At follow-up, the mean minimal luminal diameter was significantly smaller in the folate group than in the placebo group (1.59 mm vs. 1.74 mm, P=0.008), and the extent of late luminal loss was greater (0.90 mm vs. 0.76 mm, P=0.004). The restenosis rate was higher in the folate group than in the placebo group (34.5% vs. 26.5%, P=0.05), and a higher percentage of patients in the folate group required repeated target-vessel revascularization (15.8% vs. 10.6%, P=0.05). Folate therapy had adverse effects on the risk of restenosis in all subgroups except for women, patients with diabetes, and patients with markedly elevated homocysteine levels (15 micromol per liter or more) at baseline. Folate therapy and in-stent restenosis after coronary stenting. Lange H, Suryapranata H, De Luca G, Borner C, Dille J, Kallmayer K, Pasalary MN, Scherer E, Dambrink JH. Bremen, Germany. N Engl J Med. 2004 Jun 24;350(26):2673-81

Cardiovascular: B-1, B-6, B-12, and Folate Might Prevent Heart Disease & Stroke: By lowering homocysteine. 12% humans genetically predisposed to high levels homocysteine and riboflavin (found in dairy) helps. U Ulster, 10/2/02 

Depression: Vitamin B6: No Help for Cognition or Mood: In a research review of all studies to date, no trials of vitamin B6 involving people with cognitive impairment or dementia were found. The two trials (Bryan 2002; Deijen 1992) used a double-blind, randomized, placebo-controlled design and involved 109 healthy older people. One trial restricted enrolment to women and the other to men. Vitamin B6 supplementation and healthy older women: Bryan 2002 enrolled 211 healthy women from various age groups into a 5-week study. The trial was of multifactorial design with folic acid, vitamin B12, vitamin B6 and placebo in its four arms. Twelve healthy women aged 65 to 92 years received 75 mg vitamin B6 orally per day and were compared with 21 healthy women who were allocated to placebo. No statistically significant benefits from vitamin B6 on mood or cognition were observed. Vitamin B6 supplementation and healthy older men: Deijen 1992 recruited 76 healthy men aged 70 to 79 years. They were divided into 38 matched pairs, one member of each pair randomly allocated to 20 mg of vitamin B6 (pyridoxine hydrochloride) per day for 12 weeks the other to placebo. No statistically significant differences between treatment and placebo were found in their effects on cognition or mood. The effect of vitamin B6 on cognition. Malouf R, Grimley Evans J. Oxford, UK. Cochrane Database Syst Rev. 2003;(4):CD004393

Endothelium: B-6 Pyridoxine Helped in Very Small Study: DB PC 10 wk, 31 transplant cardiac patients B-6 100 mg/d or folate 5 mg/d or placebo. Only B-6 helps endothelium. Pyridoxine improves endothelial function in cardiac transplant recipients. Miner SE, Cole DE, Evrovski J, Forrest Q, Hutchison S, Holmes K, Ross HJ. J Heart Lung Transplant 2001 Sep;20(9):964-9 U Toronto

Stroke, Heart: B-6, B-12, Folate Not Helped: In a 2 year DB PC study of 3068 stroke victims given high dose (25 mg, 0.4 mg, 2.5 mg respectively) or low dose (0.2 mg, 0.006 mg, 0.02 mg), there was no difference whatsoever in strokes, heart attacks, or death during follow-up although there was a moderate decrease (2 micromol/L) in homocysteine. The study did find a more major decrease (3 micromol/L) in homocysteine was linked to decrease health risks. Lowering homocysteine in patients with ischemic stroke to prevent recurrent stroke, myocardial infarction, and death: the Vitamin Intervention for Stroke Prevention (VISP) randomized controlled trial. Toole JF, Malinow MR, Chambless LE, Spence JD, Pettigrew LC, Howard VJ, Sides EG, Wang CH, Stampfer M. JAMA. 2004 Feb 4;291(5):565-75

Schizophrenia: Vitamin B6 Doesn't Help Schizophrenia: In a 9-week, 15-patient DB PC study of vitamin B6 starting at 100 mg/day and increasing to 400 mg/day by the fourth week, PANSS scores revealed no differences between vitamin B6- and placebo-treated patients in amelioration of their mental state. Vitamin B6 as add-on treatment in chronic schizophrenic and schizoaffective patients: a double-blind, placebo-controlled study. Lerner V, Miodownik C, Kaptsan A, Cohen H, Loewenthal U, Kotler M. Ben-Gurion University J Clin Psychiatry. 2002 Jan;63(1):54-8.

B-6 Helped PMS in DB: In a DB PC crossover study of 63 patients treated with B-6 50 mg/d, authors found the supplement helped depression, irritability and fatigue 3 months each. Doll, Oxford, JR Coll Gen Prac ’89;39:364

B-6 Helped Elderly Memory, Not Mood: In a DB PC study of 76 men ages 70-79 who were treated for 3 month with B-6 10mg/day, no impact was found on mood. Mental performance improved. Vitamin B-6 supplementation in elderly men: effects on mood, memory, performance and mental effort. Deijen JB, van der Beek EJ, Orlebeke JF, van den Berg H.

B-6 Pyridoxine Helped Women on BCP in DB: DB PC crossover for depressed women who had no previous history of depression. Adams, Lancet pg 897, ‘73

Tardive Dyskinesia and B6: B6 increases cerebral serotonin function and melatonin production in animals. Four case reports of improved TD and neuroleptic parkinsonism as well as psychotic symptoms after treatment with pyridoxine. The case of a 22-year-old is presented where treatment with 20 mg/d added to haldol was followed by a drastic reduction abnormal movements after 5 days. Vladimir Lerner, Israel, J Clin Psychiatry 11/98 59:623-4. Ed: Such case reports are almost worthless and usually should never have been published since they have a high tendency to mislead physicians.  Even the authors write as if their cases prove the effectiveness of the treatment.

Tardive Dyskinesia Helped by B6 in Very Small Study: In a DB 4 week crossover study of 15 patients, B6 patients were better by 3rd week. Am J Psychiatry 2001 Sep;158(9):1511-4