Study: Wine heart benefit 'small'
Two to three glasses of wine a day may not be as good for the heart as previously thought, the study says.
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LONDON, England (CNN) -- Drinking two to three glasses of wine a day may not be such good medicine for the heart after all, a team of experts say in a leading medical journal.
Under a heading "no such thing as a free lunch," The Lancet says experts in a new study have concluded that "coronary protection from light to moderate drinking will be very small."
Various studies published in the 1970s and 1980s suggested that small to moderate alcohol consumption had a protective effect on coronary artery disease, says the report.
One suggests that having up to three drinks a day, each containing about 10 grams of alcohol, can reduce heart attack risk by a quarter.
But the celebrations may be premature, according to Dr Rod Jackson and three colleagues from the University of Auckland in New Zealand.
Writing in The Lancet, they suggest that the apparent protective effect of alcohol may be largely due to "confused research."
Instead they say any benefit from light to moderate drinking is probably small and unlikely to outweigh the harm to health caused by alcohol.
If anything, the evidence of heart protection is more convincing for heavy drinkers, say the experts.
Post mortem studies show that dead alcoholics have relatively "clean" arteries. But for this group, the dangers of alcohol abuse greatly outweigh any benefit from alcohol.
Research pointing to the protective effect of alcohol was first published in the 1970s and 1980s. These early observations were confirmed by a meta-analysis -- a pooling together of findings from different studies -- which indicated a 20 to 25 percent reduction in heart disease risk linked to light drinking.
But the Auckland team point out that these studies were not sufficiently "randomized" to avoid confounding errors.
Any positive association could easily be due to confusing factors that were not considered, the experts say. For instance, people who stop drinking because of heart problems may be misclassified as "never drinkers" in studies.
A study this year on 200,000 U.S. adults found that 27 of 30 cardiovascular risk factors were significantly more common in non-drinkers than light to moderate drinkers.
Such risk factors, already present in study participants, could sway the results, it is suggested.
"While moderate to heavy drinking is probably coronary-protective, any benefit will be overwhelmed by the known harms," say Dr. Jackson's team.
"If so, the public health message is clear. Do not assume there is a window in which the health benefits of alcohol are greater than the harms -- there is probably no free lunch."
The experts drew a comparison with the debate over hormone replacement therapy and heart disease. A non-randomized study, called the Nurses' Health Study, originally reported a halving of heart disease risk in postmenopausal women on HRT.
Later, more carefully conducted trials showed that HRT does not reduce heart disease risk, and the original findings were probably due to confounding factors.
The Nurses Health Study investigators found that light to moderate alcohol consumption offered about the same level of protection against heart disease as HRT.
Belinda Linden, head of medical information at the British Heart Foundation, told the UK's Press Association: "This comment suggests that light to moderate alcohol consumption may only give a small amount of protection against coronary heart disease, while the benefits of moderate to heavy drinking are likely to be outweighed by the overall harm that alcohol can also cause.
"The good news is that people can still enjoy alcohol in moderation, especially during the festive period.
"There is no evidence to suggest that light to moderate alcohol consumption will actually harm the heart.
"However over indulging can have an adverse effect on your health. We should not encourage people to start drinking specifically to protect their heart, as there are much safer options.
"Our advice remains the same - the best way to reduce the risk of heart disease is to quit smoking if you smoke, increase levels of physical activity and eat a healthy balanced diet."
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