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Alcohol has damaging effect on heart, finds gene study

14 July 2014
Appeared in BioNews 762

Even light alcohol consumption is a risk for cardiovascular health, a genetic study has found, contradicting previous reports that moderate drinking can be beneficial for the heart.

The analysis, published in the BMJ, looked at the drinking habits and health status of more than 260,000 participants who took part in 56 studies. The authors found that people with a genetic variant that leads to lower alcohol consumption had, on average, a ten percent reduced risk of coronary heart disease, lower body mass index and blood pressure.

'While the damaging effects of heavy alcohol consumption on the heart are well-established, for the last few decades we've often heard reports of the potential health benefits of light-to-moderate drinking', said Juan Casas, professor of epidemiology at the London School of Hygiene and Tropical Medicine, which led the study in collaboration with University College London and the University of Pennsylvania.

He continued: 'In our study, we saw a link between a reduced consumption of alcohol and improved cardiovascular health, regardless of whether the individual was a light, moderate or heavy drinker'.

The genetic variation involved in this study concerns the alcohol dehydrogenase 1B (ADH1B) gene. Those with a variant of this gene break down alcohol slowly and experience unpleasant side effects such as nausea, headache and facial flushing. This means that, on average, individuals with the ADH1B variant consume 17 percent less alcohol per week than those without it.

Previous studies have suggested that moderate alcohol consumption, 12-25 units per week, has a beneficial effect on cardiovascular health, but Professor Casas says that these studies may have missed behavioural patterns associated with low-to-moderate drinkers.

'People who drink low-to-moderate amounts are more likely to be engaging in physical activity and they're more conscious about quality of diet', he said.

Studying the long-term effects of alcohol consumption has been challenging, due to the difficulty of setting up trials involving many individuals who will maintain the same drinking levels over a period of time. However, the use of the ADH1B variant as an indicator of alcohol consumption, offered a controlled setting, which was less prone to some of the limitations of previous observational studies.

Dr Shannon Amoils, a senior research adviser at the British Heart Foundation said: 'Studies into alcohol consumption are fraught with difficulty in part because they rely on people giving accurate accounts of their drinking habits. Here, the researchers used a clever study design to get round this problem by including people who had a gene that predisposes them to drink less'.

Tim Spector, professor of genetic epidemiology at King's College London, praised the study and concluded that 'we should not accept the dogma that alcohol drinking is good for us'. But he noted: 'This study has limitations because people with genes for alcohol intolerance may also have other unmeasured behaviours or traits that reduce heart disease'.

'Asian Glow' Gene Shows Drinking Less Cuts Heart Risk
Bloomberg |  11 July 2014
Association between alcohol and cardiovascular disease: Mendelian randomisation analysis based on individual participant data
BMJ |  10 July 2014
Heart health benefits of light drinking brought into question
London School of Hygiene and Tropical Medicine (press release) |  11 July 2014
Light drinkers could still be raising risk of heart disease
Daily Telegraph |  11 July 2014
One alcoholic drink a day could raise risk of heart disease, study finds
The Guardian |  11 July 2014
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