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LETTERS: Martin Ashton-Key, Margaret Ashton-Key, Morten Grønbæk, Carole L Hart, George Davey Smith, David J Hole, and Victor M Hawthorne Alcohol consumption and mortality BMJ 1999; 319: 1267 [Full text]

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Alcohol consumption and mortality

Wayne Morriss   (16 January 2000)

Alcohol consumption and mortality 16 January 2000
Wayne Morriss Send response to journal: Re: Alcohol consumption and mortality	EDITOR - Martin and Margaret Ashton-Key1 state that a 750 ml bottle of wine containing 8% alcohol by volume contains six units of alcohol. A unit of alcohol or "standard drink" is often defined as 10 g of alcohol. The specific gravity of alcohol is 789.3 g per litre; therefore the above bottle contains 4.8 standard drinks or 48 g of alcohol (8% x 0.75 l x 789.3 g/l). In comparison, a 750 ml bottle of wine containing 12% alcohol is equivalent to 7.1 standard drinks. M and M Ashton-Key overestimate the alcohol content by 27% if a unit is defined by weight rather than volume. Therefore, it is unlikely that Hart et al's2 assumption that one bottle of wine is equivalent to 6 units would have affected the validity of the study's conclusions. Differences in the definition of a unit of alcohol add to the problem of individuals under-reporting alcohol intake. The definition of a unit of alcohol in studies done in the United States may be 50% greater than in Britain3. In a large prospective study of mortality among US adults, each drink was assumed to contain, on average, 12 g of alcohol4. In Australia, a standard drink is defined as 10 g of alcohol and labelling of alcohol containers with the number of standard drinks they contain was mandated by legislation in 1995. In Spain, investigators analysed the drinking habits of a large number of subjects in order to define a standard drink unit (SDU)5. They found that the alcohol content for an average glass of beer or wine was 10 g compared with 20 g for a measure of spirits. Reporting of alcohol consumption requires both a clear definition of a unit of alcohol and an awareness of the alcohol content of individual drinks. 10 g of alcohol is contained in approximately 285 ml of 4.5% beer, 110 ml of 12% wine, and 30 ml of 45% spirit. In the absence of a clear definition, comparison of data and recommendation of safe drinking limits are difficult. Wayne Morriss, consultant anaesthetist Department of Anaesthesia and Pain Management, Alfred Hospital, Commercial Rd, Prahran, Vic 3181, Australia 1 Ashton-Key M, Ashton-Key M. Alcohol consumption and mortality: underestimates of consumption are possible [letter]. BMJ 1999;319:1267 2 Hart CL, Smith GD, Hole DJ, Hawthorne VM. Alcohol consumption and mortality from all causes, coronary heart disease, and stroke: results from a prospective cohort study of Scottish men with 21 years of follow up. BMJ 1999;318:1725-9 3 Doll R, Peto R, Hall E, Wheatley K, Gray R. Mortality in relation to consumption of alcohol: 13 years' observations on male British doctors. BMJ 1994; 309:911-918 4 Thun MJ, Peto R, Lopez AD, Monaco JH, Henley SJ, Heath CW, Doll R. Alcohol consumption and mortality among middle-aged and elderly U.S. adults. N Engl J Med 1997;337:1705-1714 5 Gual A, Martos AR, Lligona A, Llopis JJ. Does the concept of a standard drink apply to viticultural societies? Alcohol & Alcoholism 1999;34(2):153-60