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BOSTON, MASSACHUSETTS. Researchers at the Harvard School of Public Health have
just released a major study which shows that a higher intake of folic acid and
vitamin-B6 (pyridoxine) protects women against nonfatal heart attacks
(myocardial infarction) and fatal coronary heart disease (CHD). The study
involved over 80,000 female nurses who in 1980 completed food frequency
questionnaires. The questionnaires were updated in 1984, 1986 and 1990 and also
gathered information on the use of vitamin supplements. By 1994 658 of the
women had suffered a nonfatal heart attack (MI) and 281 had died of coronary
heart disease. Statistical analysis showed that women whose intake of folate
(folic acid) exceeded 545 micrograms/day had a 31 per cent lower risk of having
a heart attack or fatal CHD than did women whose intake was less than 153
micrograms/day. Similarly, women whose intake of vitamin B-6 was greater than
5.9 milligrams/day had a 33 per cent lower risk. Women with the highest intake
of both folate and vitamin B-6 had a 45 per cent lower risk than women with the
lowest combined intake. These risk reductions were independent of other
cardiovascular risk factors such as smoking, hypertension, alcohol consumption,
and the intake of fiber, vitamin-E and saturated, polyunsaturated and
trans-fatty acids. Multivitamins and other vitamin supplements were by
far the largest contributors to the intakes of both folate and vitamin B-6.
The researchers found a linear decline in the risk of CHD with increased folate
intake (5.8 per cent decrease for each 100 micrograms/day increase in intake) in
the range between 150 to 700 micrograms/day. They conclude that the lowest risk
was among women whose folate intake was above 400 micrograms/day and whose
vitamin B-6 intake was above 3 milligrams/day. These values are considerably
higher than the current Recommended Daily Allowances (RDAs) of 200 micrograms
and 1.6 milligrams respectively. The researchers also point out that almost 90
per cent of all American women have a folate intake below 400 micrograms/day
with the average national intake being only 224 micrograms/day. A high folate
intake was found to be particularly important among women who consumed one or
more alcoholic drinks per day. In this group those with the highest folate
intake reduced their risk of MI and CHD by an astounding 73 per cent when
compared to women with a low intake. The researchers were not able to evaluate
the benefits of supplementation with more than 1000 micrograms/day of
folate.
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