Arbor B Vitamins and Stroke Prevention

892019 Arbor B Vitamins and Stroke Prevention

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Re Saposnik G et al Homocysteine-lowering therapy and stroke risk severity anddisability additional ndings rom the HOPE 2 trial Stroke 2009 Apr40(4)1365-72

Study 3 B vitamins and carotid arterial function

A recent Australian trial tested the impact o B vitamin

supplements on carotid arteries and combined this

with a meta-analysis o previous similar RCTs

Subjects and method 162 patients with previous

stroke (rom the VITATOPS trial) randomised to receive

either placebo or a B vitamin supplement (olic acid 2

mg vitamin B6 25 mg vitamin B12 500 microg) or a meano 39 yrs Carotid intima-medial thickness (CIMT) and

brachial ow-mediated dilation (FMD) were measured

In addition a meta-analysis was conducted on this

trial combined with a urther 6 previous RCTs on CIMT

NUTRITION RESEARCH REVIEW

Study 1 B vitamins and stroke severity

A new study rom Turkey looked at vitamin B12

and

olate levels in relation to outcome o acute stroke

Subjects and method Longitudinal observational

study o 109 patients with acute stroke (frac34 were

ischaemic frac14 haemorrhagic Baseline vitamin levels

were compared with initial clinical stroke severity

(Glasgow coma scale) and hospital mortality at 7 days

Results The mean initial vitamin levels were each

signifcantly lower in those who subsequently died

within 7 days than in those who survived both or

vitamin B12

(186 vs 278 pmolL p=0001) and olate

(176 vs 211 pmolL p=0003) A similar relationship

was seen between the baseline levels o the two

vitamins and worse initial Glasgow coma scale

Re Bayir A et al Acute-phase vitamin B12 and olic acid levels in patients with ischemic and hemorrhagic stroke is there a relationship with prognosis NeurolRes 2010 Mar32(2)115-118

Study 2 Is there any HOPE for stroke

A new analysis o the HOPE-2 trial ocused on the

stroke outcomes including severity

Subjects and method Multi-national RCT on 5522

patients with known CVD randomised to receive either

placebo or supplements (olic acid 25 mg vitamin

B650 mg vitamin B

121000 microg) designed to lower

homocysteine (Hcy) levels daily or 5 years

Results Compared with placebo the vitamin-

supplemented group had 25 ewer strokes non-atalones in particular Amongst those who had strokes

the severity (as judged by neurological defcit at 24 hrs

or unctional dependence at 7 days) was not improved

by supplementation See Graph

In a nutshellThe association between

elevated Hcy the B vitamins

linked to it and stroke incidence

and severity appears strong

So ar a dozen RCTs (almost

all in patients with signiicant

atherosclerosis) have tried to

prevent stroke by reducing Hcy

through various combinations

o olate B12

and B6 In only one

trial did this clearly succeed

Issue 318 Stroke amp prevention - B vitamins Arbor Clinical Nutrition Updates 2010 (Mar)3181-5 ISSN 1446-5450

Graph 1 Hazard ratio for stroke active vs placebo(Study 2)

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This issue is or the personal use o Premium subscribers only(except where being used within the terms o an institutional subscription)

Previous issues

Premium subscribers may obtain all past issues o the Updates by logging

into our web site at wwwnutritionupdatesorg

08

10

04

0

02

06

HR

12

Anystroke

14

075

Non-fatal

072 091

Fatal Functldepend

095057

gt138 le 138

(micromolL)

with initialHcy

066

892019 Arbor B Vitamins and Stroke Prevention

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COMMENTARY

The connection between homocysteine (Hcy) and

stroke is one aspect of the broader and controversial

`Hcy hypothesisrsquo - that elevated Hcy is an independent

and treatable cause of atherosclerosis including

heart disease It also concerns the vitamins closely

connected to Hcy through their role in methionine

metabolism regeneration and Hcy breakdown - see

Figure opposite Those Hcy-vitaminsrsquo are folate

vitamin B12

and to a lesser extent vitamin B6

and vitamin B2 1-3

We easily found over two dozen studies on Hcy as

a risk factor for stroke of which the large majority

reported a positive association In some recent

examples Hcy levels in stroke cases were a third

higher than in controls in one 4 and double in the other

(odds ratio for elevated Hcy a remarkable 157) 5 A

recent British study found the association strongest in

relation to small vessel strokes 6 whilst one from China

reported that elevated Hcy predicted for brain atrophy

post-stroke (OR=98) 7

Three meta-analyses (curiously each published in

2002) confirmed this association One included 30observational studies involving 1113 stroke events

and concluded that Hcy is an independent though

moderate risk factor for stroke and that in the

prospective studies stroke risk was reduced by 11

for every 25 reduction in Hcy 8 The second meta-

analysis collated 20 sets of prospective data to derive

OR=159 that a future stroke patient would have had

a 5 elevation in their baseline Hcy level 9 In the

third meta-analysis the pooled OR for subjects with

elevated Hcy having an ischaemic stroke (from 14studies involving 1769 stroke cases) was 179 10

Other epidemiological research has focused

specifically on the Hcy-vitamins and stroke Although

not entirely consistent there have been many

reports of stroke being associated with lower folate

levels (eg 7 11-14 ) somewhat fewer reports of lower

vitamin B12

(eg 13 15 16 ) and much fewer of lower

vitamin B6(eg 17 18 ) A single study found lower

vitamin B2

level in stroke patients than controls 19

but another did not 20 New Study 1 showed a link

between two of these nutrients and stroke severity

There is a genetic factor at play in this association as

well due to the extensively documented impact onHcy metabolism of polymorphism in the gene for the

MTHFR enzyme (whose role is shown in the Figure

above) A good many studies have looked at the

risk for stroke associated with the particular MTHFR

genotype (TT) in which Hcy recycling is impaired

(n=768 no other trials on stroke patients) and 20 other

RCTs on FMD (n=1282 only one other trial on stroke

patients)

Results There was no signifcant change in CIMT or

FMD in their own trial The meta-analysis showed a

decrease in CIMT (010 mm 95 CI 001-020 mm)

and increase in FMD (by 14 07-21) mainly seen

in trials o less than 9 weeks duration

Re Potter K et al The eect o long-term homocysteine-lowering on carotid intima-media thickness and fow-mediated vasodilation in stroke patients a randomized controlled trial and meta-analysis BMC Cardiovasc Disord 2008 Sep 20824

A meta-analysis in 2002 of 19 studies reported the ORfor (ischaemic) stroke in the TT genotype to be 123 10

Research since then has confirmed the link 21-24

What is not so clear is how much independent risk

this genetic variation has beyond the Hcy levels and

whether it affects the impact of Hcy lowering vitamin

supplementation with the general consensus being thatsuch effects are modest at best 10 25-27

Given that there clearly is an association three

questions spring to mind Firstly is it causal or merely

an indicator of some other process Secondly if

causal what is the mechanism and is it the Hcy or thevitamins that are the most important element Thirdly

can the damage be corrected by supplementation

In relation to causality the majority of experts have

expressed the view that the weight of evidence

suggests this is true (eg 1 28-31 ) An interesting

perspective on this comes from one of the meta-

analyses we have already cited which calculated odds

ratios from genetic and prospective studies separately

The authors concluded that since each analysis had

similar highly significant outcomes but were unlikely

to share confounders the evidence for causality was

strong 9 Others have not been so sure and havepreferred to await the results of quality RCTs 32-35

When it comes to mechanisms there is no shortage

of evidence that elevated Hcy could predispose

to stroke through contribution to inflammation

SAM

(S-Adenosyl-

methionine)

Homocysteine

Methionine

Excreted or converted

to other aa

Methionine

cycle

VitB2

NADPH

NADP+

Methioninesynthase

VitB6

VitB12

cycleFolate

MTHFR

Nucleotide

synthesis(DNA RBC etc)

Methyl

donation(nerves

DNA etc)

Cysteine

THF

5-methyl

THF

Super simplified Hcy biochemistry lesson

Methyl donation and nucleotide synthesis are both vitalfunctions served by the conversion of methionine to andregeneration from Hcy involving the folate cycle Vitamindeficiency can lead to Hcy accumulation

892019 Arbor B Vitamins and Stroke Prevention

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Some potential limitations of these trial data have been

raised One is that these supplements in the doses

used would be ineffective or the effect too weak to be

detected with the sample sizes tested in people with

the kind of advanced atherosclerotic disease that was

true of the subjects in all these trials except one 77

Let alone in patients who recently had a stroke which

was the basis of the VISP trial (included in all three

meta-analyses) - that is secondary prevention hardlycomparable with the other RCTs Moreover VISP

compared high dose Hcy-vitamins not with placebo

but with low dose And control subjects in WAFACS

were allowed to take multivitamin supplements up to

RDA level 61

atherosclerosis thrombogenesis hypertension and

impaired cerebro-arterial function a good deal of

which is contributed to by oxidative stress 29 30 36-39

For example a solid body of work shows the

relationship between Hcy and carotid intima-media

thickness (CIMT) 40-42 a measure of atherosclerosis

generally but also specifically related to stroke

risk 43-45 Whilst not all observational data has founda strong connection 46 47 a number of RCTs have

demonstrated improved CIMT after elevated Hcy was

lowered through vitamin supplements 48-53 though not

all have done so 54 New Study 3 did not demonstrate

this but when its data was added to other trial results

in meta-analysis this conclusion was supported

Another interesting light on mechanism comes from a

new Canadian study which showed that excess Hcy

can inhibit the expected migration of progenitor cells

from bone marrow to repair vascular endothelium

damaged in stroke patients

55

Mechanisms involving the Hcy-vitamins which do

not involve Hcy are less clear although some animal

evidence suggests folate may have some such

role 56 57 including in endothelial function 58 and

perhaps riboflavin in traumatic brain injury 59

This brings us to the third and most important

question can any damage caused by excess Hcy

be corrected by supplementation New Study 2 is a

fresh analysis of the HOPE-2 trial showing that the

25 protection against stroke incidence had a non-

significant trend to being for non-fatal strokes andparticularly in those subjects with higher baseline Hcy

HOPE-2 is best seen in the context of other RCTs that

have looked at this question Eleven have published

their results so far 60-71 Various combinations and

permutations of these eleven form the basis of no less

than three separate meta-analyses 72-74 That these

meta-analyses did not reach complete consensus is

perhaps not surprising bearing in mind that they did

not include all the same data - see Graph 2

Looking at that Graph it is hard to find strong support

for the idea that giving vitamins to reduce Hcy

prevents stroke Although 711 RCTs showed a risk

reduction in only one was this clearly significant That

was the HOPE-2 trial the largest on patients with past

history of diabetes or vascular disease 63 On the other

hand results from the even more recently completed

SEARCH trial of 12064 heart attack survivors 75 (as yet

unpublished) failed to show any stroke prevention 76

Some might take comfort from the sub-grouping

data in the Wang meta-analysis 74 which showed a

protective effect in patients without a stroke history

(ie primary prevention which was true of all trials barone) in those whose treatment lasted more than 3 yearsand which successfully reduced their Hcy levels

On the other hand Wangrsquos analysis was too early to

include the 2 RCT results published in 2008 (n=8532)

both lasting over 3 years but with negative results 60 61

20

07500 15

Bazzano 73

Cochrane 72

Wang 74

10 125050025

089

086

075

WENBIT60

088

WAFACS 61114

NORVIT 62

085

HOPE-2 63076

ASFAST 64045

Haemo-

dialysis 65

055

VISP 66 67104

GOES

68065

FOLARDA 69

End stage

renal 70

117

LINXIAN 71063

Overall

Durationgt 3612

Hcy reducgt 20

No strokehistory

306

3090

5442

3749

5522

315

88

3680

593

283

510

3318

077

082

071

RCTs

Meta-analyses

18086

13806

16841

9748

9018

12165

N =

N =

meta-analyses trial

incl in x1 x3x2

Graph 2 RR for stroke RCTs o Hcy lowering

vitamin supplements vs control

892019 Arbor B Vitamins and Stroke Prevention

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Reerences1 Saacutenchez-Moreno C et al Stroke roles o B vitamins homocysteine and antioxidants Nutr Res Rev 2009 Jun22(1)49-67 2 McNulty H et al Homocysteine B-vitamins and CVD Proc Nutr Soc 2008May67(2)232-73 McNulty H et al Ribolavin lowers homocysteine in individuals homozygous or the MTHFR 677C-gtT polymorphism Circulation 2006 Jan 3113(1)74-80 4 Narang AP et al Homocysteine--risk actor or ischemic stroke Indian JPh ysiol Pharmacol 2009 Jan-Mar53(1)34-85 Dhamija RK et al Homocysteine and lipoprotein (a) correlation in ischemic stroke patients J Neurol Sci 2009 Jun 15281(1-2)64-8

6 Khan U et al Homocysteine and its relationship to stroke subtypes in a UK black population the south London ethnicity and stroke study Stroke 2008Nov39(11)2943-97 Yang LK et al Correlations between olate B12 homocysteine levels and radiological markers o neuropathology in elderly post-stroke patients J Am CollNutr 2007 Jun26(3)272-88 Homocysteine Studies Collaboration Homocysteine and risk o ischemic heartdi sease and stroke a meta-analysis JAMA 2002 Oct 23-30288(16)2015- 229 Wald DS et al Homocysteine and cardiovascular disease evidence oncausality rom a meta-analysis BMJ 2002 Nov 23325(7374)120210 Kelly PJ et al Homocysteine MTHFR 677C--gtT polymorphism and risk o ischemic stroke results o a meta-analysis Neurology 2002 Aug 2759(4)529-3611 Weng LC et al Is ischemic stroke risk related to olate status or other nutr ients correlated with olate intake Stroke 2008 Dec39(12)3152-812 Larsson SC et al Folate vitamin B6 vitamin B12 and methionine intakes and risk o stroke subtypes in male smokers Am J Epidemiol 2008 Apr 15167(8)954-61

13 Weikert C et al B vitamin plasma levels and the risk o ischemic stroke andtransient ischemic attack in a German cohort Stroke 2007 Nov38(11)2912-814 Van Guelpen B et al Folate vitamin B12 and risk o ischemic and hemorrhagic stroke a prospective nested case-reerent study o plasmaconcentrations and dietary intake Stroke 2005 Jul36(7)1426-3115 Pieters B et al Periventricular white matter lucencies relate to low vitaminB12 levels in patients with small vessel stroke Stroke 2009 May40(5)1623-616 He K et al Folate vitamin B6 and B12 intakes in relation to risk o stroke among men Stroke 2004 Jan35(1)169-7417 Kelly PJ et al Inlammation homocysteine and vitamin B6 status ater ischemic stroke Stroke 2004 Jan35(1)12-518 Robinson K et al Low circulating olate and vitamin B6 concentrations risk actors or stroke peripheral vascular disease and coronary artery diseaseEur opean COMAC Group Circulation 1998 Feb 1097(5)437-4319 Gariballa S et al Ribolavin status in acute ischaemic stroke Eur J Clin Nutr 2007 Oct61(10)1237-40 20 Ross RK et al Prospective evaluation o dietary and other predictors o atal

stro ke in Shanghai China Circulation 1997 Jul 196(1)50-5 21 Biswas A et al Homocystine levels polymorphisms and the risk o ischemic stroke in young Asian Indians J Stroke Cerebrovasc Dis 2009 Mar- Apr18(2)103-10 22 Saacutenchez-Mariacuten B et al [Prevalence o methylenetetrahydroolate reductaseC677T mutation among patients with acute ischemic cerebrovascular disease in Ara gon] An Med Interna 2006 Apr23(4)153-5 23 Panigrahi I et al Role o MTHFR C677T polymorphism in ischemic strokeNeu rol India 2006 Mar54(1)48-50 24 Cantu C et al Hyperhomocysteinemia low olate and vitamin B12concentrations and methylene tetrahydroolate reductase mutation in cerebralvenous thrombosis Stroke 2004 Aug35(8)1790-4 25 Lim PS et al Polymorphism in methylenetetrahydroolate reductase gene its impact on plasma homocysteine levels and carotid atherosclerosis in ESRD patients receiving hemodialysis Nephron 2001 Mar87(3)249-56 26 Demuth K et al Opposite eects o plasma homocysteine and the methylenetetrahydroolate reductase C677T mutation on carotid artery geometry in a symptomatic adults Arterioscler Thromb Vasc Biol 1998 Dec18(12)1838-43 27 Ho GY et al Methylenetetrahydroolate reductase polymorphisms and homocysteine-lowering eect o vitamin therapy in Singaporean stroke patientsStroke 2006 Feb37(2)456-60 28 Terwecoren A et al Ischemic stroke and hyperhomocysteinemia truth or myt h Acta Neurol Belg 2009 Sep109(3)181-8 29 Pezzini A et al Homocysteine and cerebral ischemia pathogenic andther apeutical implications Curr Med Chem 200714(3)249-6330 Hankey GJ et al Clinical useulness o plasma homocysteine in vascular dise ase Med J Aust 2004 Sep 20181(6)314-831 Stanger O et al DACH-LIGA homocystein (german austrian and swiss homocysteine society) consensus paper on the rational clinical use o homocysteine olic acid and B-vitamins in cardiovascular and thromboticdiseases guidelines and recommendations Clin Chem Lab Med 2003Nov 41(11)1392-40332 Herrmann W et al Hyperhomocysteinaemia a critical review o old and new

aspects Curr Drug Metab 2007 Jan8(1)17-3133 Ntaios GC et al Vitamins and stroke the homocysteine hypothesis still indou bt Neurologist 2008 Jan14(1)2-434 Lonn E Homocysteine in the prevention o ischemic heart disease stroke andvenous thromboembolism therapeutic target or just another distraction Curr Opin Hematol 2007 Sep14(5)481-735 Wierzbicki AS Homocysteine and cardiovascular disease a review o theevidence Diab Vasc Dis Res 2007 Jun4(2)143-50

Other potential limitations of the existing trial data

include any masking effect of concurrent treatment

(eg statins) or the Hcy metabolic situation beingdifferent in the RCTs on renal failure patients 77-79 Another possible issue is the baseline status of the

Hcy-vitamins and ability to absorb them For example

people living in areas with folate-fortified flour (higher

baseline status) or with B12

malabsorption may show

less protective effect from those supplements

74 79 80

What all of this might mean is that we have not as yet

narrowed down the population group in whom Hcy

lowering prevents stroke For example we lack trials

on patients with high Hcy who have not yet displayed

clinical atherosclerosis Others have argued (both

for stroke and heart disease) that the benefits of Hcy

lowering may take years to be seen and that we do

not have enough of that kind of long term data Or

that the effect of genetic polymorphism has not been

adequately taken into account or that benefit may

be confined to even higher risk patients (such as

atherosclerotic smokers) 81 82

In short given all these consideration and at least

one substantial trial having positive results there are

certainly those who do not believe we should rule

these treatments out just yet (eg 78-82 )

At the same time it would be fair to say that the

majority view is that despite the very strong

epidemiological data such a frankly disappointing

set of trial results means that current evidence simply

does not justify using these vitamins for stroke

prevention certainly not in a routine way (eg1 33 83 )

Whilst considering these different viewpoints

and maybe even whether it might be worth giving

supplements to prevent stroke on a lsquono harm in tryingrsquo

basis we should also think about their safety On the

whole the supplement regimes used in these trials havebeen considered safe (and cheap) interventions 28

There were two exceptions NORVIT reported a

rise of borderline statistical significance in non-

fatal myocardial infarction (but not in stroke) in the

vitamin group (OR=130 95 CI 100ndash168) 62

HOPE-2 found that more of the vitamin subjects werehospitalised for unstable angina (RR=124 95 CI

104-149) compared with placebo 63 In the absence

of confirmation of such increased risk from other

trials it is hard to know what significance to place

on this (There is also the question of whether folate

might sometimes promote cancer growth - a complex

subject that will be the topic of a later issue)

Two further large RCTs involving Hcy-vitamins and

stroke prevention are due to report in the next several

years the SUFOLOM3 study on some 2500 patients

who had CHD or stroke within the previous year 83 and

VITATOPS with a target of 8000 patients who had

recent transient ischaemic attack 84 The FAVORIT and

HOST trials may a lso offer some less direct information 77

This is definitely a `watch this spacersquo topic

892019 Arbor B Vitamins and Stroke Prevention

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36 Osanai T et al Novel pro-atherogenic molecule coupling actor 6 iselevated in patients with stroke a possible linkage to homocysteine Ann Med 201042(1)79-8637 Kumar M et al Homocysteine decreases blood low to the brain due tovascular resistance in carotid artery Neurochem Int 2008 Dec53(6-8)214-938 Stanger O et al Clinical use and rational management o homocysteine olic acid and B vitamins in cardiovascular and thrombotic diseases Z Kardiol 2004 Jun 93(6)439-5339 Guilland JC et al [Hyperhomocysteinemia an independent risk actor or a simple marker o vascular disease 1 Basic data] Pathol Biol (Paris) 2003

Mar51(2)101-10 40 Baptista AP et al Inlammation homocysteine and carotid intima-mediathickness Rev Port Cardiol 2008 Jan27(1)39-48 41 Sabaliauskene Z et al [Hyperhomocysteinemia in patients with atherosclerotic extracranial disease o the carotid artery] Klin Lab Diagn 2006 Jun (6)20-2 35 42 Wang H et al Serum level o homocysteine is correlated to carotid artery athe rosclerosis in Chinese with ischemic stroke Neurol Res 2006 Jan28(1)25-30 43 Silvestrini M et al Carotid wall thickness and stroke risk in patients with asymptomatic internal carotid stenosis Atherosclerosis 2010 Jan 4 Epub 44 Cobble M et al Carotid intima-media thickness knowledge and applicationto everyday practice Postgrad Med 2010 Jan122(1)10-8 45 Sahoo R et al Common carotid intima-media thickness in acute ischemic stro ke A case control study Neurol India 2009 Sep-Oct57(5)627-30 46 Ntaios G et al Homocysteine and carotid intima-media thickness in ischemic stro ke patients are not correlated Neuropsychiatr Dis Treat 2008 Apr4( 2)477-9 47 Held C et al Correlations between plasma homocysteine and olate

concentrations and carotid atherosclerosis in high-risk individuals baseline datarom the Homocysteine and Atherosclerosis Reduction Trial (HART) Vasc Med 2008 Nov13(4)245-53 48 Nanayakkara PW et al Eect o a treatment strategy consisting o pravastatinvitamin E and homocysteine lowering on carotid intima-media thicknessendothelial unction and renal unction in patients with mild to moderatechronic kidney disease results rom the Anti-Oxidant Therapy in Chronic RenalInsuiciency (ATIC) Study Arch Intern Med 2007 Jun 25167(12)1262-70 49 Fernaacutendez-Miranda C et al Eect o olic acid treatment on carotid intima- media thickness o patients with coronary disease Int J Cardiol 2007 Jun12118(3)345-950 Hodis HN et al High-dose B vitamin supplementation and progressiono subclinical atherosclerosis a randomized controlled trial Stroke 2009Mar 40(3)730-651 Vianna AC et al Uremic hyperhomocysteinemia a randomized trial o olate treatment or the prevention o cardiovascular events Hemodial Int 2007 Apr 11(2)210-6

52 Tungkasereerak P et al Eect o short-term olate and vitamin B supplementation on blood homocysteine level and carotid artery wall thickness inchronic hemodialysis patients J Med Assoc Thai 2006 Aug89(8)1187-9353 Till U et al Decrease o carotid intima-media thickness in patients at risk tocerebral ischemia ater supplementation with olic acid Vitamins B6 and B12 Atherosclerosis 2005 Jul181(1)131-554 van Dijk RA et al Long-term homocysteine-lowering treatment with olic acid plus pyridoxine is associated with decreased blood pressure but not with improved brachial artery endothelium-dependent vasodilation or carotid artery stiness a 2-year randomized placebo-controlled trial Arterioscler Thromb VascBiol 2001 Dec21(12)2072-955 Alam MM et al Homocysteine reduces endothelial progenitor cells in stroke patients through apoptosis J Cereb Blood Flow Metab 2009 Jan29(1)157-6556 Hwang IK et al Folic acid deiciency increases delayed neuronal death DNAdamage platelet endothelial cell adhesion molecule-1 immunoreactivity and gliosis in the hippocampus ater transient cerebral ischemia J Neurosci Res 2008 Jul86(9)2003-1557 Huang GW et al [Eects o olic acid vitamin B(6) and vitamin B(12) on learning and memory unction in cerebral ischemia rats] Zhonghua Yu Fang Yi Xue Za Zhi 2007 May41(3)212-458 Doshi SN et al Folic acid improves endothelial unction in coronary artery disease via mechanisms largely independent o homocysteine loweringCirculation 2002 Jan 1105(1)22-659 Hoane MR et al Administration o ribolavin improves behavioral outcome and reduces edema ormation and glial ibrillary acidic protein expression ater trau matic brain injury J Neurotrauma 2005 Oct22(10)1112-2260 Ebbing M et al Mortality and cardiovascular events in patients treated with homocysteine-lowering B vitamins ater coronary angiography a randomizedcontrolled trial JAMA 2008 Aug 20300(7)795-804

61 Albert CM et al Eect o olic acid and B vitamins on risk o cardiovascular events and total mortality among women at high risk or cardiovascular disease a randomized trial JAMA 2008 May 7299(17)2027-3662 Boslashnaa KH et al Homocysteine lowering and cardiovascular events ater acute myocardial inarction N Engl J Med 2006 Apr 13354(15)1578-8863 Lonn E et al Homocysteine lowering with olic acid and B vitamins invascular disease N Engl J Med 2006 Apr 13354(15)1567-7764 Zoungas S et al Cardiovascular morbidity and mortality in the Atherosclerosis and Folic Acid Supplementation Trial (ASFAST) in chronic renalailure a multicenter randomized controlled trial J Am Coll Cardiol 2006 Mar

2147(6)1108-1665 Righetti M et al Homocysteine-lowering vitamin B treatment decreasescardiovascular events in hemodialysis patients Blood Puri 200624(4)379-8666 Spence JD et al Vitamin Intervention For Stroke Prevention trial an eicacy ana lysis Stroke 2005 Nov36(11)2404-967 Toole JF et al Lowering homocysteine in patients with ischemic stroketo prevent recurrent stroke myocardial inarction and death the VitaminIntervention or Stroke Prevention (VISP) randomized controlled trial JAMA 2004Feb 4291(5)565-7568 Liem A et al Secondary prevention with olic acid results o the Goesextension study Heart 2005 Sep91(9)1213-469 Liem AH et al Eicacy o olic acid when added to statin therapy in patientswith hypercholesterolemia ollowing acute myocardial inarction a randomised pilot trial Int J Cardiol 2004 Feb93(2-3)175-970 Wrone EM et al Randomized trial o olic acid or prevention o cardiovascular events in end-stage renal disease J Am Soc Nephrol 2004Feb 15(2)420-6

71 Mark SD et al Lowered risks o hypertension and cerebrovascular disease ater vitaminmineral supplementation the Linxian Nutrition Intervention Trial Am J Epidemiol 1996 Apr 1143(7)658-6472 Martiacute-Carvajal AJ et al Homocysteine lowering interventions or preventingcardiovascular events Cochrane Database Syst Rev 2009 Oct 7(4)CD00661273 Bazzano LA et al Eect o olic acid supplementation on risk o cardiovascular diseases a meta-analysis o randomized controlled trials JAMA 2006 Dec 13296(22)2720-674 Wang X et al Eicacy o olic acid supplementation in stroke prevention a met a-analysis Lancet 2007 Jun 2369(9576)1876-8275 SEARCH Study Collaborative Group et al Study o the eectiveness o additional reductions in cholesterol and homocysteine (SEARCH) characteristicso a randomized trial among 12064 myocardial inarction survivors Am Heart J 2007 Nov154(5)815-23 82376 Amritage J et al SEARCH Study Collaborative Group SEARCH (Study o the Eectiveness o Additional Reductions in Cholesterol and Homocysteine) randomized comparison o olic acid 2 mg plus vitamin b12 1 mg daily versus

placebo or 7 years in 12064 myocardial inarction survivors Circulation 2008Nov 118(22)2309-231777 Marcus J et al Homocysteine lowering and cardiovascular disease risk lost in translation Can J Cardiol 2007 Jul23(9)707-1078 Pietrzik K Opinion on the COCHRANE Review lsquorsquoHomocysteine-lowering interventions or preventing cardiovascular events European Nutraceutical As sociation website at httpwwwenaonlineorg79 Spence JD Perspective on the eicacy analysis o the Vitamin Intervention or Stro ke Prevention trial Clin Chem Lab Med 200745(12)1582-580 Ueland PM et al Homocysteine and olate status in an era o olic acidortiication balancing beneits risks and B-vitamins Clin Chem 2008May54(5)779-8181 Wald DS et al Folic acid homocysteine and cardiovascular disease judging causality in the ace o inconclusive trial evidence BMJ 2006 Nov 25333(7578)1114-782 Nainggolan L Folic acid modestly protects against cardiovascular eventsHea rtwire 2006 reproduced in Medscape web site wwwmedscapecom83 Bazzano LA Folic acid supplementation and cardiovascular disease the stateo t he art Am J Med Sci 2009 Jul338(1)48-984 Galan P et al The SUFOLOM3 Study a secondary prevention trial testingthe impact o supplementation with olate and B-vitamins andor Omega-3 PUFAon atal and non atal cardiovascular events design methods and participantscharacteristics Trials 2008 Jun 1093585 VITATOPS Trial Study Group et al VITATOPS the VITAmins TO prevent stroke trial rationale and design o a randomised trial o B-vitamin therapy in patients with recent transient ischaemic attack or stroke (NCT00097669)(ISRCTN74743444) Int J Stroke 2007 May2(2)144-50