Findings from a survey of over 22,000 US doctors have greatly
strengthened the certainty that regular, light to moderate use
of alcohol reduces the risk of stroke. As little as 1 drink per
day lowers the risk of ischaemic stroke, this being the commonest
of 2 major types of stroke and occurs when the blood supply to
part of the brain is blocked.
Over the past decade several research teams both in the USA and
Europe have claimed that a J-shaped curve, as in the case of coronary
heart disease, can be seen between alcohol intake and ischaemic
stroke. The graph showing the lowest risk of the condition among
moderate drinkers, the higher risk showing not only in heavy consumers
but also abstainers.
The definition of moderate drinking has lacked clarity as some
researchers have focused on daily intake while others have emphasised
frequency of consumption. Also a misleading impression of the
benefit of moderate drinking can result, as groups categorised
as abstainers may have included individuals who had abstained
because of poor health. The new data came from a survey designed
to clarify the matter.
American Physicians aged 40-84 were enrolled in 1982 in a wide-ranging
health study. At that time, the physicians reported no history
of stroke, or even symptoms, which might be attributed to a very
minor stroke. Other conditions that may also have led to abstention
were heart attack, cancer, liver disease and peptic ulcer.
Also recorded were the doctors' drinking habits in terms of drinks
of wine, beer or liquor per day, week or month. After 7 years
the subjects were asked again and the findings correlated very
closely with the original figures, 97% of the participants fell
into the light-to-moderate category of 1-7 drinks per week.
From 1982 onwards, every 6 months a questionnaire was sent in
which they could record evidence of newly diagnosed conditions,
including stroke. Information about deaths and causes was obtained
from relatives and confirmed by independent record. All the data
was correlated with alcohol intake data in an attempt to see what
The average follow-up period was just over 12 years, during which
697 strokes occurred.
Subjects who consumed more than one drink per week were approximately
20% less likely to have a stroke than those who took less than
one per week were. When the findings for the two different types
of stroke were separated, the reduction in risk for ischaemic
stroke was slightly greater than that for strokes in general.
No significant relationship was found between alcohol intake and
the other much less common type of stroke, which occurs when a
blood vessel haemorrhages into the brain.
The protective effect of as little as one drink per week was revealed
on closer inspection of different categories of alcohol intake.
However, greater consumption, up to one drink per day, did not
increase the benefits any further. The investigators conclude
that while the findings "may be important for persons who consume
alcoholic beverages with low or moderate frequency", no generalisation
should be drawn in terms of lifestyle advice.
The investigators point out that heavy drinking is a risk factor
for both types of stroke and also cite claims that any overall
increase alcohol consumption in a population is likely to be accompanied
by a proportionate rise in heavy drinking.
Source:Light-to-Moderate Alcohol Consumption and the Risk of Stroke Among
U.S. Male Physicians, New England Journal of Medicine (1999), 341, 1557-64, Berger K., Ajani U.A., Kase C.S., Gaziano
J. M., Buring J.E., Glynn R.J.and Hennekens C.H., Division of Preventive
medicine, Department of Medicine, Brigham and Women's Hospital;
Department of Veterans Affairs Boston Healthcare System; Department
of Ambulatory Care and Prevention, Harvard Medical School; Department
of Biostatistics, Harvard School of Public Health; and Department
of Neurology, Boston University School of Medicine, Boston, MA;
Institute of Epidemiology and Social Medicine and Department of
Neurology, University of Muenster, Muenster, Germany; Department
of Epidemoilogy and Public Health, University of Miami, Miami,