You could be taking years off your life by regularly drinking more than the advised UK guidelines for alcohol, according to new research from an international team. The finding applies equally to women and men.

The large study of almost 600,000 drinkers showed that people who drank more than 12.5 units (100g) of alcohol a week were likely to die sooner than those who drank no more than this amount.

Current UK guidelines recommend limiting alcohol intake to 14 units a week for women and men. This is equivalent to drinking no more than 6 pints of average-strength beer (4% ABV) or 7 medium-sized glasses of wine (175ml, 12% ABV) a week.

These limits are lower than the levels for many other countries, but this latest study suggests they are about right. However, drinking above this limit was linked with lower life expectancy.

For example, having 10 or more drinks per week was linked with 1-2 years shorter life expectancy. Having 18 drinks or more per week was linked with 4-5 years shorter life expectancy.

Cardiovascular Conditions

The study also looked at the likelihood of having a range of non-fatal, but potentially life-changing, cardiovascular conditions, including heart attacks, heart failure and stroke.

Alcohol consumption was associated with a higher risk of stroke, heart failure, fatal aortic aneurysms, fatal hypertensive disease and there were no clear thresholds where drinking less did not have a benefit. By contrast, alcohol consumption was associated with a slightly lower risk of non-fatal heart attacks.

The authors note that the different relationships between alcohol intake and various types of cardiovascular disease may relate to alcohol’s elevating effects on blood pressure and on factors related to elevated high-density lipoprotein cholesterol (HDL-C) (also known as good cholesterol). They stress that the lower risk of non-fatal heart attack must be considered in the context of the increased risk of several other serious and often fatal cardiovascular diseases.

The work was conducted by a collaboration of 120 researchers worldwide, from regions including Australia, Europe, Japan, the UK and the US. It was a meta-analysis of individual-level data from 83 prospective cohort studies carried out in 19 countries.

This type of research – especially when carried out at this scale and with the care the authors took to ensure their methods were robust – is a good way to summarise the best research we have on a particular subject.

However, the studies analysed were all observational studies, as it wouldn’t be ethical to carry out studies where some people were encouraged to drink an unhealthy amount of alcohol. This means we have to be cautious when saying alcohol was the direct cause of the additional deaths, because other confounding factors may have affected the results.

Study Results

Of the 599,912 people in the study, 40,310 died and 39,018 got cardiovascular disease during an average 7.5 years of follow-up. About half of the people in the study reported drinking more than 12.5 units of alcohol a week.

Looking at different levels of alcohol consumption, the researchers found:

  • people drinking up to 12.5 units of alcohol a week had the lowest risk of death from any cause

  • above that level, the risk of death rose to a more than 30% increased risk for those drinking more than 37 units a week

  • each additional 12.5 units of alcohol consumed each week increased the risk of stroke by 14% (hazard ratio [HR] 1.14, 95% confidence interval [CI] 1.10 to 1.17)

  • each additional 12.5 units of alcohol consumed each week decreased the risk of heart attack by 6% (HR 0.94, 95% CI 0.91 to 0.97)

  • the risk of all other cardiovascular conditions increased with each additional 12.5 units of alcohol consumed

When they applied their figures to life expectancy at age 40, the researchers calculated that compared with people drinking up to 12.5 units a week:

  • those who drank 12.5 to 25 units a week were likely to live 6 months less

  • those who drank 25 to 44 units were likely to live 1 to 2 years less

  • those who drank more than 44 units were likely to live 4 to 5 years less

Looking at UK limits (14 units a week), the researchers said that compared with those who drank within current limits:

  • men who drank above the limits would lose an average of 1.6 years (95% CI 1.3 to 1.8)

  • women who drank above the limit would lose an average of 1.3 years (95% CI 1.1 to 1.5)

Drinking Less

Dr Angela Wood, from the University of Cambridge, lead author of the study said:

“The key message of this research is that, if you already drink alcohol, drinking less may help you live longer and lower your risk of several cardiovascular conditions. Alcohol consumption is associated with a slightly lower risk of non-fatal heart attacks but this must be balanced against the higher risk associated with other serious - and potentially fatal - cardiovascular diseases."

The study did have a couple of limitations that are worth noting.

In many of the individual studies included in the meta-analysis, the participants were asked only once about how much alcohol they drank – and people are notoriously bad at accurately reporting their drinking. However, if people in the studies routinely underestimated their alcohol consumption, that would mean the meta-analysis results tend towards underestimating the harm alcohol causes.

And while the researchers did their best to account for a range of factors that could have affected the results, it’s always hard to control for those completely.

Overall, the study, which was funded by the UK Medical Research Council, British Heart Foundation, National Institute for Health Research in the UK, European Union and European Research Council, backs up the recommendations that both women and men drink within the UK limits of 14 units of alcohol a week.

Wood, Angela M et al. Risk thresholds for alcohol consumption: combined analysis of individual-participant data for 599 912 current drinkers in 83 prospective studies The Lancet, Volume 391, Issue 10129, 1513 - 1523

Image: Thomas Hawk/Flickr

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