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Vitamin B May Be Dangerous for Heart Attack Patients
Sept. 6, 2005 - Researchers from Norway have found
that treating patients who have had a heart attack with high doses of B
vitamins does not lower the risk of getting another heart attack or
stroke. Contrary to their expectations, B vitamins may do more harm than
good.
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Folic Acid Mandated for U.S. Cereal Products
The U.S. Food and Drug Administration
mandated folic acid fortification of enriched cereal-grain
products in 1998 and recent research says Vitamin B levels have
improved significantly in every segment of the U.S. population.
Folic acid is a synthetic version of folate,
a member of the vitamin B complex. Food fortification was aimed
largely at preventing birth defects that can occur when pregnant
women are deficient in folate.
"Folate fortification is an example of how
easily the vitamin status of the entire population can be
improved with a relatively simple and cost-effective measure,"
Dr. Christine M. Pfeiffer from the Centers for Disease Control
and Prevention, Atlanta, told Reuters Health.
In the last survey, only 5 percent of the US
population had high homocysteine levels and 2 percent had
elevated methylmalonic acid levels.
"The US folic acid fortification program
might have other benefits beyond the reduction of the incidence
of (birth) defects," Pfeiffer said. "Due to the homocysteine-lowering
effect of folate, reductions could be expected in the incidence
of vascular diseases."
Mandatory folic acid fortification "may be
the most important science-driven intervention in nutrition and
public health in decades," writes Dr. Irwin H. Rosenberg from
Tufts University, Boston, in a related editorial in the August
issue of American Journal of Clinical Nutrition. |
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More related stories:
Vitamin B Rich Folates Significantly Reduce Alzheimers Disease
Risk
Coffee is Number One Source of Antioxidants in American Diet
Folic acid fortification may
have lowered stroke deaths
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These surprising data were presented at the Hot
Line Session II of the European Society of Cardiology Congress in
Stockholm yesterday.
NORVIT, the Norwegian Vitamin Trial, is the first
trial to examine whether high doses of B vitamins prevent recurrent
heart disease in patients. A total of 3749 patients were recruited from
35 Norwegian hospitals. The patients were assigned to take B vitamins or
placebo for more than three years in addition to standard treatments
after a heart attack.
Professor Kaare Harald Bψnaa MD, University of
Tromsψ, Norway, principal investigator of the NORVIT trial, comments,
"The results of the NORVIT trial are important because they tell doctors
that prescribing high doses of B vitamins will not prevent heart disease
or stroke. B vitamins should be prescribed only to patients who have B
vitamin deficiency diseases."
The participants in the NORVIT trial were divided
at random into four groups that received either 0.8 mg folic acid (a B
vitamin) per day, 40 mg vitamin B-6 per day, both 0.8 mg folic acid and
40 mg vitamin B-6 per day, or a placebo capsule per day. Those who took
folic acid or vitamin B-6 alone had a small increase in the risk of
cardiovascular disease. However, among those who took both vitamins the
risk increased by 20 percent.
During the last 15 years interest in vitamin B
research has rocketed worldwide because studies indicated that folic
acid and vitamin B-6 could prevent heart disease and stroke. Researchers
have believed that this was due to the ability of B vitamins to lower
the blood level of an amino acid called homocysteine. It was thought
that high levels of homocysteine may damage the lining of arteries and
increase clotting of the blood. This can cause fatal blockages of
arteries in the heart and brain.
"Some doctors have found the previous data so
compelling that they have already started to treat patients with B
vitamins to lower the homocysteine level. However, in the NORVIT trial,
homocysteine levels were lowered by 30%, but this did not lower the
patients' risk of cardiovascular disease", said Kaare Harald Bψnaa MD.
There were no subgroups of patients in the NORVIIT
trial who benefited from taking B vitamins. Harmful effects were seen in
particular among those who had high levels of homocysteine at the start
of the trial, among patients with impaired renal function, and among
those who reported that they used other vitamin supplements in addition
to the study medication.
The results of the NORVIT trial are supported by
results of a recent, smaller study which used similar doses of B
vitamins as those given in NORVIT. That study showed that B vitamins
increased the risk of reocclusion of coronary arteries that had been
opened by percutaneous revascularization.
One patient in every three who suffers a heart
attack has a recurrent heart attack or stroke within three years after
the first attack, even if they get the best medical treatment available.
It was hoped that B vitamins could lower the risk of recurrence. The
NORVIT trial showed, however, that B vitamins offer no protection
against cardiovascular disease.
The NORVIT trial was conducted by researchers at
the University of Tromsψ, Norway, in cooperation with researchers at the
University of Bergen, Norway, and doctors and nurses at 35 Norwegian
hospitals. It was a low-budget trial financed by the Norwegian Research
Council, the Council on Health and Rehabilitation, the Norwegian Council
on Cardiovascular Research, and other non-profit organizations.
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