Unit of alcohol

Units of alcohol are a measure of the volume of pure alcohol in an alcoholic beverage. Such units are used in some countries as a guideline for a drinker's alcohol consumption.

One unit of alcohol is defined as 10 millilitres in the United Kingdom, and as 10 grams (12.7 ml) in Australia. In both countries, a so-called standard drink contains one unit of alcohol (according to the country's own definition). The definition of a "standard drink" varies significantly in other countries.

In the United Kingdom, the number of units contained in a typical serving of an alcoholic beverage is publicised and printed on bottles.

In one hour, an average healthy adult can metabolize about 75% of an Australian unit of alcohol or 95% of a United Kingdom unit.

1 Formulae
2 Quantities
3 Limits
4 See also
5 References

Formulae

The number of UK units of alcohol in a drink can be determined by multiplying the volume of the drink (in millilitres) by its percentage ABV, and dividing by 1000. Thus, one pint (568 ml) of beer at 4% ABV contains:

$\frac{568 \times 4}{1000} = 2.3\mbox{ units}$

The formula uses the quantity in millilitres divided by 1000; this has the result of there being exactly one unit per percentage point per litre of any alcoholic beverage.

You can also think of 4% as being $\frac{4}{100}$ Hence .04 X 568 mL gives the amount of alcohol in mL, which you then dived by 10 to show the number of units.

When the volume of an alcoholic drinks is shown in centilitres, determining the number of units in a drink is as simple as multiplying volume by percentage (converted into a fraction of 1). Thus 75 centilitres of wine (the contents of a standard wine bottle) at 12 % ABV contain:

$75 \times 0.12 = 9\mbox{ units}$

Quantities

It is often stated that a unit of alcohol is supplied by a small glass of wine, half a pint of beer, or a single measure of spirits.^[1] Such statements may be misleading because they do not reflect differences in strength of the various kinds of wines, beers, and spirits.

Beers

A half pint (284 ml) of beer that has a strength of 3.5% abv contains almost exactly one unit. However, most beers are stronger. In pubs, beers generally range from 3.5% to 5.5% abv with continental lagers starting at around 5% abv. A pint of such lager (568 ml at 5.2% for example) is almost 3 units of alcohol, rather than the often-quoted value of 2 units per pint.
A 500 ml can/bottle of standard lager (5%) contains 2.5 units.
'Super-strength' or strong pale lager may contain as much as two units per half pint.
One litre of typical Oktoberfest beer (5.5% to 6%) contains 5.5 to 6 units of alcohol.

Wines

A medium glass (175 ml) of 12% abv wine contains around two units of alcohol. However, British pubs and restaurants often supply larger quantities (large glass: 250 ml) which contain 3 units. Red wine might have a higher alcohol content (on average 12.5%, sometimes up to 16%).
A 750 ml bottle of 12% abv wine contains 9 units. Some port wines may contain 20% abv or more, which is 15 units of alcohol per bottle.
A 750 ml bottle of 14.5% abv wine contains 10.88 units.

Fortified wines

A small glass (50 ml) of sherry, fortified wine, or cream liqueur (approx. 20% abv) contains about one unit.

Spirits

Most spirits sold in the United Kingdom have 40% ABV or slightly less. In Great Britain, a single pub measure (25 ml) of a spirit contains one unit.

However, a larger 35ml measure is increasingly used (and in particular is standard in Northern Ireland ), which contains 1.4 units of alcohol.

Alcopops

Most alcopops contain 1.4 to 1.5 units per bottle. For example, a regular 275ml bottle of WKD contains 1.4 units,^[2] whereas Bacardi Breezer and Smirnoff Ice both contain 1.5 units of alcohol.^[3]

Limits

Main article: Recommended maximum intake of alcoholic beverages

Since 1995 the UK government has advised that regular consumption of 3–4 units a day for men, or 2–3 units a day for women, would not pose significant health risks, but that consistently drinking four or more units a day (men), or three or more units a day (women), is not advisable.^[4]

Previously (from 1992 until 1995), the advice was that men should drink no more than 21 units per week, and women no more than 14.^[5] (The difference between the sexes was due to the typically lower weight and water-to-body-mass ratio of women.) This was changed because a government study showed that many people were in effect "saving up" their units and using them at the end of the week, a phenomenon referred to as binge drinking. The Times reported in October 2007 that these limits had been "plucked out of the air" and had no scientific basis.^[6]

An international study^[7] of almost 6,000 men and 11,000 women found that persons who reported that they drank more than 2 units of alcohol a day had an increased risk of fractures compared to non-drinkers. For example, those who drank over 3 units a day had nearly twice the risk of a hip fracture.

References

^ "Alcohol and the athlete". BUPA. Archived from the original on 2007-06-07. http://web.archive.org/web/20070607232015/http://www.bupa.co.uk/health_information/html/healthy_living/lifestyle/exercise/diet_exercise/athalc.html. Retrieved 2007-07-29.
^ "Alcohol". http://www.wkd.co.uk/pages/about/. Retrieved 2008-12-31.
^ "Alcohol". http://www.ciao.co.uk/Smirnoff_Ice__Review_5302466. Retrieved 2008-12-31.
^ http://www.dh.gov.uk/en/Publichealth/Healthimprovement/Alcoholmisuse/index.htm
^ http://www.drinkaware.co.uk/facts/factsheets/health-fact-sample-2
^ Drink limits ‘useless’, The Times, 20 October 2007
^ Kanis JA, Johansson H, Johnell O et al. (July 2005). "Alcohol intake as a risk factor for fracture". Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA 16 (7): 737–42. doi:10.1007/s00198-004-1734-y. PMID 15455194.