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Vitamin B6 for cognition

  • Review
  • Intervention


  • Reem Malouf,

    Corresponding author
    1. Oxfordshire and Buckinghamshire Mental Health Trust, Department of Neurology, Oxford, UK
    • Reem Malouf, Department of Neurology, Oxfordshire and Buckinghamshire Mental Health Trust, John Radcliffe Hospital (4th Floor, Room 4401C), Headington, Oxford, OX3 9DU, UK.

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  • John Grimley Evans

    1. University of Oxford, Division of Clinical Geratology, Nuffield Department of Clinical Medicine, Oxford, UK
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Micronutrient status can affect cognitive function at all ages. Vitamin deficiencies could influence memory function and might contribute to age-associated cognitive impairment and dementia. Vitamin B6, comprising three chemically distinct compounds, pyridoxal, pyridoxamine, and pyridoxine, is involved in the regulation of mental function and mood. Vitamin B6 is also an essential homocysteine re-methylation cofactor, and deficiency is associated with an increase in blood homocysteine levels. Homocysteine is a risk factor for cerebrovascular disease and may also have directly toxic effects on neurons of the central nervous system. Neuropsychiatric disorders including seizures, migraine, chronic pain and depression have been linked to vitamin B6 deficiency. Epidemiological studies indicate that poor vitamin B6 status is common among older people. Hyperhomocysteinaemia has been suggested as a cause or mechanism in the development Alzheimer's disease and other forms of dementia. Supplementation with B vitamins including vitamin B6 has been shown to reduce blood homocysteine levels.


To assess the efficacy of vitamin B6 supplementation in reducing the risk of developing cognitive impairment by older healthy people, or improving cognitive functioning of people with cognitive decline and dementia, whether or not vitamin B6 deficiency has been diagnosed.

Search methods

The Specialized Register of the Cochrane Dementia and Cognitive Improvement Group (CDCIG), The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL and LILACS were searched on 16 March 2008 using the terms: B6, "B 6", B-6, pyridoxine, pyridoxamine, pyridoxal. The CDCIG Specialized Register contains records from all major health care databases (The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL, LILACS) as well as from many trials databases and grey literature sources.

Selection criteria

All unconfounded, double-blind randomized controlled trials in which the intervention with vitamin B6 was compared with placebo for healthy older people or people with cognitive decline or dementia. The primary outcome of interest was the efficacy of vitamin B6 supplementation on cognitive function.

Data collection and analysis

The two reviewers independently evaluated all studies identified as possibly meeting the criteria for inclusion. One reviewer independently extracted the data. Studies were rated for their overall quality. The weighted mean differences between treatment and placebo groups, with 95% confidence intervals, were calculated for each outcome. Review Manager version 4.2 was used to analyse the variance.

Main results

No trials of vitamin B6 involving people with cognitive impairment or dementia were found.

The two trials included in the review (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 five-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.

Effect of vitamin B6 supplementation on vitamin B6 status:

Deijen 1992, reported that 20 mg of pyridoxine hydrochloride per day for 12 weeks increased blood vitamin B6 activity as assessed as by plasma pyridoxal-5'-phosphate (WMD 238, 95%CI 211.58 to 264.42, P<0.00001) and erythrocyte enzyme asparate aminotransferase (WMD 0.43, 95%CI 0.30 to 0.56, P<0.00001)

Effect of vitamin B6 supplementation on blood homocysteine concentration:

Neither of the included trials measured homocysteine levels.


All participants allocated to vitamin B6 or placebo completed the trial protocol.

Adverse events:

No adverse effects were reported.

Effect of vitamin B6 on carer burden, care costs and institutionalization rate:

We found no trials in which these outcomes were assessed.

Authors' conclusions

This review found no evidence for short-term benefit from vitamin B6 in improving mood (depression, fatigue and tension symptoms) or cognitive functions. For the older people included in one of the two trials included in the review, oral vitamin B6 supplements improved biochemical indices of vitamin B6 status, but potential effects on blood homocysteine levels were not assessed in either study.

This review found evidence that there is scope for increasing some biochemical indices of vitamin B6 status among older people. More randomized controlled trials are needed to explore possible benefits from vitamin B6 supplementation for healthy older people and for those with cognitive impairment or dementia.








2008年3月16日に、用語B6、”B6”、B-6、ピリドキサル、ピリドキサミン、ピリドキシンを用いてSpecialized Register of the Cochrane Dementia and Cognitive Improvement Group(CDCIG)、コクラン・ライブラリ、MEDLINE、EMBASE、PsycINFO、CINAHL、LILACSを検索した。CDCIG Specialized Registerは主要なすべての保健医療データベース(コクラン・ライブラリ、MEDLINE、EMBASE、PsycINFO、CINAHL、LILACS)ならびに多数の試験データベースおよび灰色文献の情報源からの記録を含んでいる。







本レビューで抽出された2つの試験(Bryan 2002;Deijen 1992)では、二重盲検ランダム化プラセボ対照のデザインが用いられており、109名の健常高齢者が登録されていた。1件の試験では参加者が女性に限定されており、その他の試験では男性に限定されていた。


Bryan 2002では、様々な年齢群に属する211名の健常女性が5週間の試験に登録されている。この試験は多元的デザインで実施されており、葉酸、ビタミンB12、ビタミンB6、プラセボの4投与群が設定されている。65~92歳の健常女性12名にビタミンB6を75mg/日にて投与し、プラセボ群に割付けられた21名の健常女性と比較された。気分あるいは認知に対するビタミンB6の統計的に有意な効果は認められなかった。


Deijen 1992では、70~79歳の健常男性76名が登録された。マッチする38組に分けられ、各組の1名がビタミンB6(塩酸ピリドキシン)を20mg/日にて12週間投与する群、各組の他方がプラセボ群に割付けられた。認知または気分に対する効果から、治療群とプラセボ群との統計的有意差は見出されなかった。


Deijen 1992では、血漿中ピリドキサル-5'-リン酸(WMD 238、95%CI 211.58~264.42、P<0.00001)および赤血球酵素アスパラギン酸アミノトランスフェラーゼ(WMD 0.43、95%CI 0.30~0.56、P<0.00001)から評価したところ、塩酸ピリドキシンを20mg/日にて12週間投与することにより、血中ビタミンB6活性が上昇すると報告されている。













《注意》この日本語訳は、臨床医、疫学研究者などによる翻訳のチェックを受けて公開していますが、訳語の間違いなどお気づきの点がございましたら、eJIM事務局までご連絡ください。なお、2013年6月からコクラン・ライブラリーのNew review, Updated reviewとも日単位で更新されています。eJIMでは最新版の日本語訳を掲載するよう努めておりますが、タイム・ラグが生じている場合もあります。ご利用に際しては、最新版(英語版)の内容をご確認ください。

Plain language summary

No evidence of benefit from vitamin B6 supplementation on mood or cognition of older people with normal vitamin B6 status or with vitamin B6 deficiency

Micronutrient status can affect cognitive function at all ages. Vitamin deficiencies could influence memory function and might contribute to age-associated cognitive impairment and dementia. Vitamin B6 is involved in the regulation of mental function and mood and in the metabolism of homocysteine, a risk factor for vascular disease. Two trials of vitamin B6 supplements for healthy elderly people qualified for this review, with no beneficial effects on mood or mental function detectable. Homocysteine levels were not assessed. No ill effects of vitamin B6 were observed. No trials studying effects of vitamin B6 treatment for people with dementia or cognitive impairment were identified.

Laički sažetak

Nema dokaza o koristi vitamina B6 na raspoloženje ili kognitivnu funkciju kod starijih osoba s normalnom razinom vitamina B6 ili s nedostatkom vitamina B6.

Razina mikronutrijenata može utjecati na kognitivnu funkciju u bilo kojoj dobi. Nedostatci vitamina mogu utjecati na funkciju pamćenja i mogli bi doprinijeti kognitivnom poremećaju i demenciji povezanima s dobi. Vitamin B6 sudjeluje u regulaciji mentalne funkcije i raspoloženju te u metabolizmu homocisteina, rizičnog čimbenika za bolest krvnih žila. Dva su istraživanja nadoknade vitamina B6 kod zdravih starijih osoba bila prihvatljiva za ovaj pregled, a nisu otkrila korisne učinke na raspoloženje ili mentalnu funkciju. Razine homocisteina nisu se ocjenjivale. Nisu zabilježeni štetni učinci vitamina B6. Nisu nađena istraživanja koja ispituju učinke tretmana vitaminom B6 osoba s demencijom ili kognitivnim oštećenjem.

Bilješke prijevoda

Hrvatski Cochrane
Prevela: Katarina Vučić
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《注意》この日本語訳は、臨床医、疫学研究者などによる翻訳のチェックを受けて公開していますが、訳語の間違いなどお気づきの点がございましたら、eJIM事務局までご連絡ください。なお、2013年6月からコクラン・ライブラリーのNew review, Updated reviewとも日単位で更新されています。eJIMでは最新版の日本語訳を掲載するよう努めておりますが、タイム・ラグが生じている場合もあります。ご利用に際しては、最新版(英語版)の内容をご確認ください。