Researchers: Folic acid may reduce heart attack risk

[Roman Byst]

"Researchers: Folic acid may reduce heart attack risk", USA
Today, November 24, 2006, Link: http://blogs.usatoday.com/ond-
eadline/2006/11/researchers_fol.html

British researchers said today that taking folic acid
supplements may reduce the risk of heart attacks,
Reuters reports.

"The evidence is very persuasive" that folic acid can "lower
your risk of heart attack and stroke by about 10-20%," David
Wald, of the Wolfson Institute for Preventive Medicine, Barts
and the London, Queen Mary School of Medicine and Dentistry in
London, said in an interview with the news service.

Folic acid appears to lower the level of the amino acid
homocysteine in subjects' blood, which the researchers say is
a cause of cardiovascular disease.

He and others involved in the study published their findings
in the British Medical Journal.

[Matti Nark]

On 24 Nov 2006 09:36:12 -0800, "Roman Bystrianyk"
<rbystrianyk@gmail.com> wrote:

>"Researchers: Folic acid may reduce heart attack risk", USA
>Today, November 24, 2006, Link: http://blogs.usatoday.com/on-
>deadline/2006/11/researchers_fol.html
>
>British researchers said today that taking folic acid
>supplements may reduce the risk of heart attacks,
>Reuters reports.
>
>"The evidence is very persuasive" that folic acid can "lower
>your risk of heart attack and stroke by about 10-20%," David
>Wald, of the Wolfson Institute for Preventive Medicine, Barts
>and the London, Queen Mary School of Medicine and Dentistry
>in London, said in an interview with the news service.
>
>Folic acid appears to lower the level of the amino acid
>homocysteine in subjects' blood, which the researchers say is
>a cause of cardiovascular disease.
>
>He and others involved in the study published their findings
>in the British Medical Journal.

The reference and the link tot the full text of the study are

Cardiovascular disease: Folic acid, homocysteine, and
cardiovascular disease: judging causality in the face of
inconclusive trial evidence David S Wald, Nicholas J Wald,
Joan K Morris, Malcolm Law BMJ 2006;333:1114-1117,
doi:10.1136/bmj.39000.486701.68
<http://www.bmj.com/cgi/content/full/333/7578/1114>

This study interests me mainly, because it explains why in the
clinical trials folic acid has not yet reduced the risk of CVD
statistically significantly, although epidemiogical studies
have shown clear benefits. According to this study the reason
is, that the effect is expected to be so small, only 10-15%
reduction in CVD events, and that due to the relative small
number of CVD events in the conducted trials, the trials have
lacked statistical power to detect this small effect. However,
although the results have not been statistically significant,
they have been consistent with a 12% reduction in ischaemic
heart disease and a 22% reduction in stroke (, but also
consistent with no reduction). Here from the study a quote,
which handles clinical trials evidence:

"Randomised trials, although valuable, are not the only
source of evidence on efficacy of interventions. In some
situations they are not needed—for example, in
establishing that stopping smoking prevents ischaemic
heart disease and lung cancer. It is sometimes said that
associations in epidemiological studies—for example,
between antioxidant vitamins and ischaemic heart disease
events11 12—have incorrectly been thought to be causal
when subsequent randomised trials showed otherwise.13
However, confounding by socioeconomic status was
acknowledged as a reasonable explanation for the observed
association with antioxidant vitamins.11 12 Trials were
needed because of legitimate doubt. In the case of
homocysteine and ischaemic heart disease, the position is
different; the evidence from cohort studies is supported
independently by the genetic evidence from MTHFR
polymorphism studies, which are not subject to such
confounding, and the observations from patients with
homocystinuria show that the risk is reversible.

Randomised trials of the effect of reducing homocysteine
concentrations on myocardial infarction and stroke are in
progress, and some have been reported. Folic acid is
expected to reduce cardiovascular disease events by only
about 10-15% (compared, for example, to about an 80%
reduction in neural tube defects from taking 5 mg folic
acid daily). The modest effect and the relatively small
number of events recorded in the published randomised
trials (about 2000 compared to 32 000 in the
meta-analyses of genetic studies) mean that the trials
lack statistical power. Despite this, the reports from
individual studies tend to inappropriately interpret non-
significant effects as evidence of no effect. This is
shown in figure 2 by the wide confidence intervals around
the estimates from each trial in a meta-analysis of
published trials of homocysteine reduction on disease
events.14 15 16 17 18 19 20 Even with all the reported
trial results together there is a lack of statistical
power; the results are consistent with a 12% reduction in
ischaemic heart disease and a 22% reduction in stroke
(from the lower 95% confidence limits on the summary
relative risk estimates) but also consistent with no
reduction. If the only evidence available were the trial
results, we would still be in the dark.

[...]

In addition, some of the trials were short term (less than
two years), and it is uncertain how long it would take for
any risk reversal to emerge. With reductions in serum
cholesterol concentrations it takes two years for the near
maximal effect to become apparent.21 In the recent heart
outcomes prevention evaluation (HOPE-2) trial, which
showed a significant reduction overall in the risk of
stroke, the published survival curve shows no reduction in
risk of cardiovascular disease in the first two years but
a modest risk reduction in the third and fourth years.20
We believe it is misleading to conclude that the results
from trials such as HOPE-2 are negative.

An analogy exists with medical judgments made after the
early randomised trials of treatment to reduce serum
cholesterol concentrations. The early trials achieved only
modest reductions in serum cholesterol and their duration
was short; the two years necessary for the near maximal
reduction in ischaemic heart disease events was not
appreciated. Consequently, the modest risk reductions
observed were not significant and were widely interpreted
as negative. Cholesterol reduction was claimed to be
harmful, and in 1992 a moratorium on the use of all
cholesterol lowering drugs was suggested.22"

--
Matti Narkia

[I.P. Freel]

> "Roman Bystrianyk" wrote:
>
>> British researchers said today that taking folic acid
>> supplements may reduce the risk of heart attacks, Reuters
>> reports.
>>
>> Folic acid appears to lower the level of the amino acid
>> homocysteine in subjects' blood, which the researchers say
>> is a cause of cardiovascular disease.

Nothing new there. Besides, we could do something radical,
like consume FOOD containing folic acid, as healthy eaters
have done for decades. I get an RDA's worth of it daily just
from cereal alone (and my homocysteine is very low).

I.P.

[Juhana Har]

I.P. Freely wrote:
:: "Roman Bystrianyk" wrote:
::
::: British researchers said today that taking folic acid
::: supplements may reduce the risk of heart attacks, Reuters
::: reports.
:::
::: Folic acid appears to lower the level of the amino acid
::: homocysteine in subjects' blood, which the researchers say
::: is a cause of cardiovascular disease.
:
: Nothing new there. Besides, we could do something radical,
: like consume FOOD containing folic acid, as healthy eaters
: have done for decades. I get an RDA's worth of it daily just
: from cereal alone (and my homocysteine is very low).

That is a too simplistic answer as there are genetical factors
affecting the homocysteine levels. For people with very high
homocysteine levels dietary changes are not enough.

http://tinyurl.com/y5y3q4

--
Juhana