Unit of alcohol

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A "large" (250 ml) glass of 12% ABV red wine has about three units of alcohol. A "medium" (175 ml) glass, such as the one shown, has about two units.[Note 1]

Units of alcohol are used in the United Kingdom (UK) as a measure to quantify the actual alcoholic content within a given volume of an alcoholic beverage, in order to provide guidance on total alcohol consumption.

A number of other countries (including Australia, Canada, New Zealand, and the USA) use the concept of a "standard drink", the definition of which varies from country to country, for the same purpose. "Standard drinks" were referred to in the first UK guidelines (1984) that published "safe limits" for drinking, but these were replaced by references to "alcohol units" in the 1987 guidelines and the latter term has been used in all subsequent UK guidance.[1]

One unit of alcohol (UK) is defined as 10 millilitres (8 grams) of pure alcohol.[2][3] Typical drinks (i.e. typical quantities or servings of common alcoholic beverages) may contain 1–3 units of alcohol.[3]

In contrast to the system of "standard drinks" used in other countries, the UK unit of alcohol is independent of both the strength (% alcohol by volume (ABV)) and amount (volume) of any individual alcoholic beverage. The system is intended to provide guidance to people on how much alcohol they drink in a manner that can readily be totalled across across a multiple of alcoholic beverages of differing strengths and serving sizes.

Containers of alcoholic beverages sold directly to UK consumers are normally labelled to indicate the number of units of alcohol in a typical serving of the beverage (optional) and in the full container (can or bottle), as well as information about responsible drinking.[4] Additionally, the advent of smartphones has led to the creation of apps which report the number of units contained in an alcoholic drink.[5]

As an approximate guideline, a typical healthy adult can metabolise (break down) about one unit of alcohol per hour,[3] although this may vary depending on gender, age, weight, health, and many other factors.

Formula[edit]

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.

For example, one imperial pint (568 ml) of beer at 4% alcohol by volume (ABV) contains:

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

The formula uses ml ÷ 1000. This results in exactly one unit per percentage point per litre, of any alcoholic beverage.

Since 4% can be expressed as 0.04, then 0.04 × 568 ml gives the amount of alcohol in terms of ml—which, when divided by 10, shows the number of units.

When the volume of an alcoholic drink is shown in centilitres, determining the number of units in a drink is as simple as volume × 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 12/100 {{=}} 9.0\mbox{ units}

Labelling[edit]

Example of Wine Bottle label in accordance with UK voluntary health labelling scheme

UK alcohol companies pledged in March 2011 to implement an innovative health labelling scheme to provide more information about responsible drinking on alcohol labels and containers. This voluntary scheme is the first of its kind in Europe and has been developed in conjunction with the UK Department of Health. The pledge stated:[6]

"We will ensure that over 80% of products on shelf (by December 2013) will have labels with clear unit content, NHS guidelines and a warning about drinking when pregnant."

At the end of 2014, 101 companies had committed to the pledge labelling scheme.[6]

There are five elements included within the overall labelling scheme, the first three being mandatory, and the last two optional:

  1. Unit alcohol content per container (mandatory) & per serving (optional)
  2. Chief Medical Officers’ daily guidelines for lower-risk consumption
  3. Pregnancy warning (in text or as a graphic)
  4. Mention of "drinkaware.co.uk" (optional)
  5. Responsibility statement (e.g. “please drink responsibly”) (optional)
Further detailed specifications about the labelling scheme are available from the "Alcohol labelling tool kit".[7]

Drinks companies had pledged to display the three mandatory items on 80% of drinks containers on shelves in the UK off-trade by the end of December 2013.[7] A report published in Nov 2014, confirmed that UK drinks producers had delivered on that pledge with a 79.3% compliance with the pledge elements as measured by products on shelf. Compared with labels from 2008 on a like-for-like basis, information on Unit alcohol content had increased by 46%; 91% of products displayed alcohol and pregnancy warnings (18% in 2008); and 75% showed the Chief Medical Officers’ lower risk daily guidelines (6% in 2008).[8]

Quantities[edit]

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.[9] Such statements may be misleading because they do not reflect differences in strength of the various kinds of wines, beers, and spirits.

Chart showing alcohol unit count for drink size and ABV

Beers[edit]

Wines[edit]

Fortified wines[edit]

Spirits[edit]

Most spirits sold in the United Kingdom have 40% ABV or slightly less. In England 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[citation needed]), which contains 1.4 units of alcohol at 40% ABV. Sellers of spirits by the glass must state the capacity of their standard measure in ml.

Alcopops[edit]

Time to metabolise[edit]

On average, it takes about one hour for the body to metabolise (break down) one unit of alcohol. However, this can vary with body weight, sex, age, personal metabolic rate, recent food intake, the type and strength of the alcohol, and medications taken. Alcohol may be metabolised more slowly if liver function is impaired.[12]

Recommended maximum[edit]

From 1992 to 1995 the UK government advised that men should drink no more than 21 units per week, and women no more than 14.[13] (The difference between the sexes was due to the typically lower weight and water-to-body-mass ratio of women[citation needed].) The Times reported in October 2007 that these limits had been "plucked out of the air" and had no scientific basis.[14][15]

This was changed after 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.[citation needed] Since 1995 the advice was 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.[16]

An international study[17] of about 6,000 men and 11,000 women for a total of 75,000 person-years found that people who reported that they drank more than a threshold value of 2 units of alcohol a day had a higher risk of fractures than non-drinkers. For example, those who drank over 3 units a day had nearly twice the risk of a hip fracture.

See also[edit]

Notes[edit]

  1. ^ Even though the sizes of wine glasses are defined in UK law, the terms "large", "medium", "standard" etc are not defined in law.

References[edit]

  1. ^ "Alcohol guidelines, Eleventh Report of Session 2010–12" (PDF). UK Parliament. House of Commons, Science and Technology Committee. 7 December 2011. p. 7. Retrieved 13 February 2015. 
  2. ^ "Drinkaware - What is an alcohol unit?". 
  3. ^ a b c "How long does alcohol stay in your blood?". NHS Choices. Retrieved 11 February 2015. 
  4. ^ "Alcohol Labelling". Retrieved 11 February 2015. 
  5. ^ "The Alculator". 
  6. ^ a b "Alcohol Labelling pledge". Dept of Health (UK). Retrieved 13 February 2015. 
  7. ^ a b "UK Alcohol Health Labelling". Portman Group. Portman Group. Retrieved 13 February 2015. 
  8. ^ "Drinks companies achieve voluntary alcohol labelling target". Portman Group. Portman Group. Retrieved 13 February 2015. 
  9. ^ "Alcohol and the athlete". BUPA. Archived from the original on 7 June 2007. Retrieved 29 July 2007. 
  10. ^ The volume of the drink in litres multiplied by its percentage strength in ABV give the number of units. In this case, 0.568 × 5.2 gives 2.95, i.e., almost 3 units.
  11. ^ "Question:- "How much alcohol is there in WKD vodka blue?"". Retrieved 27 April 2013. 
  12. ^ UK NHS:How long does alcohol stay in your blood?, reviewed 2013
  13. ^ "Health Effects of Alcohol". Drinkaware.co.uk. Retrieved 27 May 2013. 
  14. ^ Drink limits ‘useless’, The Times, 20 October 2007
  15. ^ The great alcohol myth, The Guardian, 26 January 2009
  16. ^ "Sensible drinking". NIdirect Government Services. 2013. Retrieved 27 May 2013. 
  17. ^ 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. 

External links[edit]