Folic Acid May Lower Stroke Risk
Researchers Say Benefits Are Greatest Among People Who Take Supplements the Longest
May 31, 2007 -- Folic acid supplements appear to reduce the risk of stroke,
particularly in people who do not get enough of this B vitamin.
When findings from eight previously reported studies were combined,
researchers found the benefits were greatest among people who took folic acid
supplements the longest.
But it is not clear if folic acid supplements are indeed associated with a
lower risk of heart attack and stroke or if supplements are safe for
"We only looked at stroke as an outcome, and we saw a clear benefit for
supplementation in people who had not had previous strokes," researcher
Xiaobin Wang, MD, PhD, tells WebMD.
Folic Acid Targets Homocysteine
Folic acid lowers blood levels of homocysteine, an amino acid widely
believed to play a role in stroke and heart disease. Some studies have shown
benefits from homocysteine lowering with folic acid, while others have not.
In research published last year, folic acid supplements were not found to
reduce the risk of heart attacks or death in high-risk people but did appear to
lower stroke risk.
A widely reported study, also published last year, suggested that folic acid
supplements and two other B vitamins may actually increase heart risk in
In an effort to better understand the research, Wang and colleagues from
Chicago's Northwestern University Feinberg School of Medicine limited their
analysis to studies which assessed the impact of folic acid supplements on
The largest improvements in stroke risk were seen in people who:
- Took folic acid supplements for more than three years (29% lower
- Achieved the highest reductions in blood homocysteine levels (23% risk
- Had no prior history of stroke (25% reduction).
Taking folic acid supplements was also found to lower stroke risk by 25%
among people living in areas where grains have not been fortified with folic
Fortification of breads, cereals, and other grains began in the U.S. in 1998
in an attempt to reduce the risk of neural tube birth defects, a birth defect
affecting the spinal cord and brain. Spinach and other leafy green vegetables
and dried beans and peas are also good food sources of the B vitamin.
With the exception of women who are pregnant or nursing, Wang says people in
the U.S. who eat healthy diets probably get enough folic acid in the foods they
She says more research is needed to determine if folic acid supplements are
beneficial for lowering stroke risk in these people.
University of Wisconsin professor of medicine Cynthia M. Carlsson, MD, tells
WebMD that many questions must be answered before folic acid supplements can be
recommended to lower stroke risk.
"While there may be certain subgroups of people who may benefit from
homocysteine-lowering therapy, it is premature to recommend folic acid for
primary stroke prevention," she says.