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Alcohol and Mortality in the Over 50s

Two studies published this week, conducted in Britain and Denmark, report on the combined effects of exercise and alcohol on the risk of death (from any cause). Both studies found that moderate drinkers (less than 14 units per week) had a lower risk of dying in the ten or twenty years of the study than non-drinkers and heavier drinkers. However, neither study asked their non-drinking group whether they had recently given up drinking (perhaps for health reasons) or whether they had always been abstainers.

The British study, conducted by Kay-Tee Khaw and colleagues at Cambridge University, was conducted with the aim of developing and evaluating a simple measure of health behaviours that could be used by GPs and the general public. Over 20,000 people aged 45-79 at the start of the study were surveyed between 1993 and 1997, and again in 2006. The measure gave one point for each of four health related behaviours, namely not smoking, being physically active, drinking moderately and eating five portions of fruit and vegetables per day. The points are then simply added up to give a score from zero to four. This score was strongly related to the risk of dying before the end of the eleven year study, such that people with a score of zero had four times the risk of dying as people with a score of four.

Because the purpose of the study was to evaluate the new scale, the report did not include much detail on the effects of drinking. However, they did compare moderate drinkers (1-14 units per week) with others (combining non-drinkers with heavier drinkers) on risk of death from all causes, cardiovascular disease, cancer and other causes, over the eleven years of the study. Relative to moderate drinkers, others had a 26% greater risk of dying from any cause. This increased risk was greater for cardiovascular disease and cancer (29% and 28% respectively) than other causes (17%).

Considering men and women separately, the increased risk was higher for men (35% increased risk overall), particularly for cancer (46% increased risk). For women, there was no overall increased risk, but for cardiovascular disease, ‘others’ had a 37% higher risk than moderate drinkers. The different results for men and women may be explained by the fact that for men ‘others’ were mostly heavier drinkers (74% of the others drank more than 14 units per week) whereas for women the ‘others’ were mostly nondrinkers (only 31% drank more than 14 units per week). This means that for men, the comparison was between moderate drinkers and (mostly) heavier drinkers whereas for women, the comparison was between moderate drinkers and (mostly) nondrinkers.

The Danish study, conducted by Jane Ostergaard Pedersen and colleagues at the National Institute of Public Health, University of Southern Denmark, investigated the combined effects of drinking and leisure-time physical activity. Almost 12,000 people aged 20 years or older took part in the study between 1976 and 1978 and follow up data were collected in 2001 and 2004. Participants were classified as inactive (less than 2hrs of light physical activity per week), having a low level of activity (2-4 hrs of light physical activity per week) or having a moderate to high level of activity (at least 4 hrs of light activity or at least 2 hrs of vigorous activity per week). weekly alcohol intake was classified as none (less than one drink per week), moderate (1-14 drinks per week) or heavy (more than 14 drinks per week).

Overall, alcohol had no effect on the risk of dying within the 20 years of this study. However, for people with low or moderate to high levels of physical activity, those with a moderate alcohol intake reduced the risk of dying by 10% to 13%, relative to nondrinkers (who were not asked if they had previously been drinkers). For inactive people, there was no benefit of alcohol consumption. Conversely, any regular physical activity reduced the risk of death by around 20%, regardless of alcohol intake.

The study was published in the European Heart Journal and also specifically investigated heart disease. In this case, both alcohol and exercise were beneficial, such that inactive moderate drinkers had a similar risk of dying from heart disease to teetotallers with low levels of physical activity. Both groups had around 30% lower risk of death than inactive teetotallers. Relative to the same group, moderate drinkers who were also somewhat active had around half the risk of dying from heart disease.

Both studies define moderate drinking as between one and fourteen units/drinks per week. The UK unit is precisely defined as 8 g or 10 ml alcohol, though in practice it can mean considerably more, as it is often equated to a glass of wine, which can be as much as three times this amount. A ‘standard’ drink in Denmark contains 12 g or 15 ml alcohol. A small glass of wine (125 ml; the old pub measure) contains 16 ml alcohol. A typical UK wine glass is 250 ml.

The Danish study reported that men classified as moderate drinkers actually drank an average (median) of seven drinks per week and women in the same category drank an average of four or five drinks per week. Therefore, the benefit of moderate drinking found in this study was gained from a weekly alcohol intake equivalent to two and half glasses of wine (or pints of beer) for men and one and a half glasses of wine (or pints of beer) for women.

Neither of the two studies examined different age groups separately. Whilst the Danish study used an age-stratified sample of people over the age of 20, the average (median) age of their participants was 55 for the most active and 60 for the least active, at the start of their twenty year study. The British study included people aged between 45 and 79, with an average (mean) age of 58 at the start of their eleven year study. It is well established that any benefit of moderate drinking is found only in older people. For men this starts at the age of about 40 and for women this starts at around 55.

In summary, both studies found a small benefit of having a few drinks per week, relative to not drinking at all. The majority of people who took part in both of these studies were in their 50s or older at the start of the studies.

Sources:

Khaw et al (2007) Combined impact of health behaviours and mortality in men and women: The EPIC-Norfolk prospective population study. PLoS Medicine 5(1) e12

Pedersen et al (2007) The combined influence of leisure-time physical activity and weekly alcohol intake on fatal ischaemic heart disease and all-cause mortality. European Heart Journal. http://eurheartj.oxfordjournals.org/cgi/content/full/ehm574v1