Folic acid supplements can reduce risk of stroke
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FSA is poised to recommend folic acid fortification of bread or
flour |
Folic acid supplementation can reduce the risk of stroke in those with no history of the disease, according to research published in The
Lancet (2007;369:1876). A second study published this week
indicates that folic acid supplementation is of no benefit for secondary
prevention
of colo-rectal adenomas, and may increase the risk of some types of
colorectal tumours (JAMA 2007;297:2351).
In the Lancet study, researchers conducted a meta-analysis of eight randomised
controlled trials involving 16,841 participants, which compared folic
acid supplementation (with or without other B vitamins) with placebo,
a lower dose of folic acid or usual care for a minimum of six months.
Dose of folic acid ranged from 0.5mg per day to 15mg per day. Stroke
was reported as one of the endpoints.
The analysis showed that folic acid supplementation reduced the risk
of stroke by 18 per cent (relative risk 0.82, 95 per cent confidence
interval 0.68–1.00; P=0.045). Further stratified analyses showed
that greater benefit was seen in the trials in which participants had
no history of stroke (0.75, 0.62–0.90; P=0.002), supplements were
given for more than 36 months (0.71, 0.57–0.87; P=0.001), homocysteine
levels were reduced by more than 20 per cent (0.77, 0.63–0.94;
P=0.012) and participants lived in countries without grain fortification
(0.75, 0.62–0.91; P=0.003).
“Our meta-analysis provides coherent
evidence that folic acid supplementation can significantly reduce the
risk of stroke in primary prevention,” the researchers say. However,
they acknowledge that there is continued controversy over whether folic
acid supplementation can lead to improved outcomes for other cardiovascular
endpoints, with some trials yielding negative results.
The JAMA study was a randomised controlled trial of 1,021 adults with
a recent history of colorectal adenomas (a precursor to colorectal cancer),
who received folic acid 1mg daily or placebo (with or without aspirin).
During the first three years, the incidence of at least one colorectal
adenoma was
similar in the folic acid and placebo groups (44.1 per cent versus 42.4
per cent; P=0.58), as was the incidence of at least one advanced
lesion (11.4 per cent versus 8.6 per cent; P=0.15). Three to
five years later, the
incidence of at least one colorectal adenoma was similar in the two groups
but the
incidence of at least one advanced lesion was higher in the folic acid
group (11.6 per cent versus 6.9 per cent; P=0.05). Folic acid
was also associated with higher risks of having three or more adenomas
and of
non-colorectal cancers.
Mandatory fortification The Food Standards Agency
is to recommend mandatory fortification of food with folic acid to
UK health ministers as part
of a package of measures
to help prevent neural tube defects. At its meeting in Nottingham last month,
the board asked for further work to consider whether folic acid should be added
to either bread or flour and agreed that controls on voluntary fortification
were an essential part of its recommendation. |
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The
Pharmaceutical Journal
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