Giving up the booze – even temporarily – results in an increased risk of developing coronary heart disease (CHD), a review of six long-term studies has found.
In a paper published in the journal BMC Medicine, researchers led by Dara O’Neill from University College London in the UK found that variations in moderate alcohol intake heightened the likelihood of heart disease. Lifelong non-drinkers and people who gave up drinking permanently also showed higher incidences of CHD than those who maintained regular moderate alcohol intake.
The study reviewed six longitudinal alcohol drinking studies, five from the UK and one from France, involving a total of 35,132 people. Over an approximate 10-year period, 4.9% of participants experienced a CHD event, some of them fatal.
Analysing the figures, O’Neill and colleagues found that the lowest risk of coronary illness occurred in “consistently moderate drinkers”, defined as males who consumed up to 168 grams of ethanol, and women who consumed up to 112 grams, each week.
A half-pint of beer, single glass of wine or single shot of spirits was estimated to contain eight grams of ethanol.
People who drank alcohol, but at levels that varied over time between none and too much, experienced “a significantly greater risk” of CHD. Increased risk was also detected among people who gave up alcohol, and among those who were lifelong abstainers. In the latter category, however, the boost applied only to women.
Perhaps surprisingly, no evidence of increased CHD risk was found among heavy drinkers – but the researchers suggest this result should be regarded as potentially suspect.
“Given that heavy drinkers are known to be under sampled in population level surveys, interpretation of the absence of effect amongst heavy drinkers in the current study should be done very cautiously, particularly in light of the known wider health impact of heavy alcohol intake levels,” says O’Neill.
The researchers also caution that the elevated CHD risk among inconsistent moderate tipplers might not relate directly to alcohol intake itself. Instead, it may reflect other factors, such as periods of illness or life stress, which result in a change to drinking patterns.
“When we split the sample by age, we found that the elevated risk of incident CHD amongst inconsistently moderate drinkers was observed in participants aged over 55, but not those aged below,” notes O’Neill.
“It may be that the older group experienced lifestyle changes, such as retirement, which are known to co-occur with increases in alcohol intake and that these could have played a role in the differing risk.”
The study was observational in nature, so offers no insight into cause and effect. However, the researchers suggest that the results imply that many current public health messages around alcohol consumption – particularly those that encourage an annual month of sobriety – may be off target.
“This finding suggests that policies and interventions specifically encouraging consistency in adherence to lower-risk drinking guidelines could have public health benefits in reducing the population burden of CHD,” they conclude.