Press release issued 4 March 2008The relationship between heavy drinking and hypertension is more significant than previously thought according to a new analysis of recent studies by researchers at Bristol University, published today in PLoS Medicine.
Previous observational studies have reported that heavy alcohol intake is a risk factor for hypertension but such studies may be confounded by factors such as diet, smoking, exercise levels and socio-economic position. Clinical trials exploring the link are difficult to implement and have limited follow-up time.
The Bristol study, led by Dr Sarah Lewis of the University’s Department of Social Medicine, took a different approach focused on people who have a mutation on a gene which affects their body’s ability to eliminate alcohol.
Alcohol is initially metabolised to an intermediate compound, acetaldehyde, which is further metabolised and then eliminated from the body. The major enzyme responsible for this elimination is aldehyde dehdyrogenase 2 (ALDH2).
In some people, a genetic mutation leads to an inability to metabolize acetaldehyde and causes an accumulation of acetaldehyde after alcohol intake. This mutation is common in some Asian populations and results in facial flushing after consumption of alcohol coupled with intense nausea, drowsiness, headache and other unpleasant symptoms. People with this mutation therefore drink much less than those without it
The researchers looked at the ALDH2 genotype, comparing the blood pressure of those who have this mutation – the *2 *2 genotype – with those who do not – the *1 *1 genotype.
The study found that individuals with the *1 *1 genotype, who had an alcohol intake of around 3 units per day, had strikingly higher blood pressure than those with the *2 *2 genotype, who tend to drink only very small amounts, or no alcohol.
Dr Lewis said: “This study shows that alcohol intake may increase blood pressure to a much greater extent, even among moderate drinkers, than previously thought. Large-scale replication studies are required to confirm this finding and to improve the precision of our estimates.”
Alcohol Intake and Blood Pressure: A Systematic Review Implementing a Mendelian Randomization Approach by Lina Chen, George Davey Smith, Roger M. Harbord, Sarah J. Lewis PLoS Medicine Article #07-PLME-RA-1367R2
This study shows that alcohol intake may increase blood pressure to a much greater extent, even among moderate drinkers, than previously thought.