Measure for Measure: What evidence is there for UK drinking guidelines?

Dr Sally Adams, Lecturer in Health Psychology

As an alcohol researcher, a couple of questions I often get asked are “How much alcohol can I drink?” and “How much is too much?” I attempt to answer by describing the UK government weekly guidelines of no more that 21 units for males and no more than 14 units for females and the daily guidelines that state males should not regularly exceed 3-4 units per day and 1-2 units for females. I might also throw in the recommended 2-3 alcohol-free days per week. However I have recently stopped to think about the answers I give, wondering where the evidence for these guidelines came from. Inevitably this led to several other questions: Who suggested these guidelines? Are they still relevant?

Looking at the guidelines set by The Department of Health and adopted by the National Institute for Health and Care Excellence (NICE) the first question I have is; What is all this units business? Units were intended as a simple measure of the amount of alcohol in a drink and a method for comparing the alcohol content of different drinks. A unit represents 8 grams of pure alcohol and takes approximately 1 hour for the average adult to break down (i.e. for the alcohol to leave the blood).

Whilst this may be a useful measure for standardising drinks, it does not appear to improve a drinker’s knowledge about alcohol. The Office for National Statistics suggests that the general public’s understanding of what constitutes a unit has improved in recent years. Even so, only just over half of the men asked (who drank beer) were able to identify the correct number of units in half a pint. One of the problems may be that different strengths of alcohol can change the number of units in a drink. For example whilst a pint of Carlsberg (3.8%) contains just over 2 units, a pint of Stella Artois (4.8 %) has almost 3 units. Although this difference may seem small it could affect whether you’d be over the drink-drive limit.

11037565_10153750029680663_44632274546704025_nWhat is a standard pint? and how many units does it have?

Secondly, where did the notion of units and the recommended drinking guidelines come from? And what evidence is there to support the suggested amounts? Historically, weekly recommended drinking guidelines were based on evidence presented by the Royal College of Physicians (RCP) in 1987. The report offered recommendations for “sensible” drinking limits based on input from leading doctors and the evidence available at the time. However, the report does acknowledge that the research used to make these recommendations was insufficient for making confident statements about how much alcohol is safe. The resulting report and guidelines therefore represent the best judgement possible about relative risk of alcohol use at the time.

Reports that alcohol in small amounts may be protective against coronary heart disease (CHD) led to the re-examination of these guidelines. This in itself is interesting, given that evidence has shown an association between moderate drinking and lower risk of CHD, but there remains no clear evidence that alcohol causes a reduction in risk (but that’s another story). The review of drinking guidelines, based on advice from the RCP and the British Medical Association suggested the 1987 guidelines were still the most suitable for communicating risk to the public. At this review daily benchmarks for sensible drinking were also set to address concern with episodes of heavy drinking i.e. binge drinking. Guidelines recommend no more 1-2 units per day for females and no more than 3-4 unit for males. Advice to not drink for 48 hours following a binge (to allow the body to recover) was also put forward. A problem with these new recommendation is that they appear to approve daily drinking, which is potentially a risk factor for alcohol abuse and dependency. If the daily limit of 4 units for a man was drunk this would increase the weekly alcohol limit to 28 units per week, which marks over a 30 % increase on the 1987 guidelines. Perhaps most concerning is the fact these changes were not supported by a review of the evidence on drinking limits by the RCP.

Aside from minor tweaks, no real revisions of these 20-year old recommendations have been made (and this is a really long time in science and research!). However, in 2011, an inquiry into drinking guidelines was ordered by the House of Commons. This consultation included public health experts, but sadly also included members of the alcohol industry (who have a vested interest in the sale of alcohol). The inquiry led to the setting up of a working group to review the evidence for drinking recommendations, however to date the guidelines remain unchanged. Most recently the coalition government recognised the need to address poor knowledge of drinking limits and evidence that many drinkers drink above the recommended guidelines. The Chief Medical Officer has been tasked with overseeing a review of drinking guidelines that will;

…” take account of available science on how we can best communicate the risks from alcohol, improving the public’s understanding of both personal risks and societal harms”

The concerns I report at the beginning of this piece are reflected in the RCP’s call for clear, evaluated methods for communicating drinking guidelines. The RCP also recommend that guidelines should be improved to reflect the evidence based for “levels of safe drinking”, the effects of drinking frequency and the impact of ageing on drinking limits.

As an alcohol researcher and a drinker, I hope these recommendations are followed to allow drinkers to make informed choices about the amount and frequency of their alcohol use. Is there truly a “safe amount of alcohol?” and at what levels does alcohol consumption increases the risk of alcohol-related diseases? Finally is it too much to expect that these guidelines will be delivered in the near future and will be purely evidence based?