Alcohol has damaging effect on heart, finds gene study

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'.