House of Commons - Alcohol Guidelines - Science and Technology Committee

Alcohol Guidelines - Science and Technology Committee Contents

3 The evidence base

The 1995 Sensible Drinking report

15. As explained in the previous chapter, today's alcohol guidelines arose from a review of the Government's sensible drinking message in the light of evidence which indicated that drinking alcohol might give protection from coronary heart disease.[29] The findings of the review were published in the 1995 report Sensible Drinking.[30] The Department of Health explained the process that the working group had followed:

The authors of the 1995 report drew upon a wide range of research, including epidemiological evidence, and written and oral advice of experts, as set out in the report. The report considers the harmful effects of alcohol consumption to both health and mortality and considers the evidence for its potential benefits. [...]

16. Sources of evidence to the 1995 review included relevant reports of the various Royal Colleges.[32] As mentioned in paragraph 5, these reports had re-endorsed the 1987 consumption guidelines of no more than 21 units of alcohol for men and 14 for women per week.[33]

Weekly vs. daily guidelines

17. Possibly the most significant change in the guidelines following the 1995 Sensible Drinking report was the move from providing weekly guidelines to daily guidelines. Dr Richard Harding, member of the 1995 Sensible Drinking working group, explained that the working group had thought it sensible to move away from advice based on weekly consumption in favour of daily consumption because "weekly drinking could mask episodes of heavy drinking (21 units/week could be consumed in two binges of 10 units each)". The working group also considered that it was difficult for individuals to keep account of their own consumption over a week. Furthermore, there was evidence that showed there could be benefit in regular drinking, so long as it was moderate. As a result, the working group decided to couch advice in terms of daily drinking.[34]

The Sensible Drinking report therefore stated that for men:

Regular consumption of between 3 and 4 units a day by men of all ages will not accrue significant health risk.

And for women:

Regular consumption of between 2 and 3 units a day by women of all ages will not accrue any significant health risk.

18. Two concerns were raised about the shift to daily guidance. First, the change appeared to increase the weekly "allowance" of alcohol from 21 for men and 14 for women to 28 for men and 21 for women. The Institute of Alcohol Studies (IAS) argued that the move:

Secondly, some felt that the move "appeared to endorse daily drinking".[38] This issue is examined in paragraph 49 where we look at drinking patterns.

HEALTH BENEFITS OF DRINKING ALCOHOL

19. The primary rationale for the shift to daily guidelines was evidence that regularly drinking alcohol at low quantities may confer health benefits, particularly in relation to coronary heart disease (CHD), which, according to Dr Marsha Morgan, Institute of Alcohol Studies, is where "the biggest body of evidence on the potential beneficial effects of alcohol" lies.[39]According to the 1995 Sensible Drinking report, "the evidence shows alcohol consumption confers protection from CHD mortality, starting at levels as low as 1 unit a day".[40] However, the report also cautioned that there was only a slight dose response relationship, meaning that drinking more than one to two units a day "confers only a little extra benefit" and that at very high levels of consumption, the risk of mortality increases.[41]

20. The report summarised possible biological mechanisms that would explain the beneficial effect, although it acknowledged that a causative mechanism had not been firmly established. It explained that a major cause of CHD is deposition of fatty tissues in coronary arteries, largely consisting of cholesterol, which cause narrowing or blockages of arteries. In blood, two types of protein work to either increase or decrease cholesterol levels. Simply put, low density lipoproteins (LDL) carry most of the cholesterol in blood and high density lipoproteins (HDL) remove cholesterol. It is the ratio of LDL and HDL that determines how much cholesterol is deposited in fatty tissues in arteries. The report stated that:

Another significant biological mechanism was thought to be that alcohol reduced blood clotting. Additional and less widely acknowledged mechanisms were also offered, including that alcohol:

a) might lower blood pressure;

b) caused increased blood flow;

c) could reduce coronary artery spasm induced by stress.[43]

However the report noted that "the full significance of these additional mechanisms awaits further research".[44] The submission from the International Scientific Forum and Alcohol in Moderation stated that "the message is little and often as the blood thinning effect of alcohol lasts for approximately 24 hours and one drink confers the benefit".[45] Interestingly, the report also explored the theory that the low rates of CHD in predominantly wine drinking countries could be caused by the presence of antioxidants and other constituents in wine. The report concluded that "overall, current research indicates that the major factor conferring benefit is probably alcohol rather than the other constituents of wine".[46]

21. The report highlighted other potential benefits from drinking alcohol, including mixed evidence for the effects of alcohol on stroke risks and a possible protective effect from gallstones. It had also been reported that there could be a reduced risk of non insulin-dependent diabetes, stress, rheumatoid arthritis, gastro-intestinal diseases and colds, although the report stated that "in our view, this evidence is not sufficiently strong or consistent to inform public policy".[47]

22. The theory that drinking alcohol at low quantities might confer health benefits greater than abstainers would enjoy, but that drinking alcohol at high quantities increases mortality risk is represented by the J-shaped curve. Figure 1: The J-shaped curve for all cause mortality and alcohol consumption[48]

Explanatory note: A confidence interval helps assess the likelihood of a result occurring by chance. A confidence interval represents a range of values that is believed to encompass the "true" value with high probability (usually 95%). In figure 1, this means that the wider the gaps between confidence intervals surrounding the trends for men and women, the more uncertainty there is.

The International Scientific Forum on Alcohol Research and Alcohol in Moderation explained that:

The greater uncertainty for women, represented by the wider confidence intervals, may be due to a lack of evidence: the Sensible Drinking report noted that "sufficient studies on all cause mortality do not exist to indicate clearly the advantages or disadvantages of alcohol to women as compared to men".[50] This issue is explored further in paragraph 29.

23. The evidence we took during this inquiry suggested that a number of experts were less convinced that alcohol caused beneficial effects in the body. For example, Sir Ian Gilmore, Royal College of Physicians, stated:

Professor Nick Heather, Alcohol Research UK, agreed, and stated:

Dr Marsha Morgan noted that "there is enormous contention [...] in general" and pointed out that "if there were to be a cardio-protective effect, it would selectively be found in middle-aged men and post-menopausal women, and you do not gain that protective effect in middle life by drinking at a younger age".[53] She also disputed the evidence for other beneficial effects of alcohol and highlighted evidence that had emerged since 1995 on alcohol-related cancer risks:

The two other areas where there have been alleged protective effects are in the development of diabetes and possibly [...] on the development of cancers. However, the evidence is very thin. There is no body of evidence like that for the cardio-protective effect. Much more important, since the guidelines were last considered in 1995, is that the major body of evidence has been on the detrimental effect of alcohol and the cancer risk, particularly for breast cancer in women, and that the risk levels are not far off the top end of the current guidelines. Although there have been some reports in the press for a protective effect about diabetes and some types of cancer, there is not a strong evidence base.

24. One reason why the beneficial effects of alcohol are disputed lies in the methods used to gather data and produce studies. To determine whether alcohol has a beneficial effect, the mortality risks of drinkers must be compared to lifelong non-drinkers, or abstainers. We heard that some studies had in fact included "sick quitters"—that is, individuals who abstained from alcohol because "they have an alcohol problem or are unwell"—in the abstainer category.[55] This would make abstainers appears less healthy and thus indicate that there could be health benefits gained from drinking alcohol. Professor Heather stated that more careful research on the cardio-protective effects of alcohol had shown that "people who were classified as lifetime abstainers were not really lifetime abstainers".[56] In response, Dr Richard Harding, member of the working group, stated that:

In addition, there are methodological difficulties that arise from proving causation; that is, whether alcohol itself confers health benefits rather than confounding factors such as eating healthily and exercising, which may be common behaviours amongst moderate drinkers. Studies may also be skewed by inaccurate reporting of alcohol consumption by individuals.[58] The Department of Health's view on the matter was that:

We asked Anne Milton MP, Parliamentary Under-Secretary of State for Public Health, whether the Government believed that alcohol had beneficial effects. She responded:

Dr Mark Prunty, Senior Medical Officer for Substance Misuse Policy, Department of Health, added:

It is true that the number of studies has increased and multiplied. There have been major reviews which have looked at the methodology underpinning those studies and questioned their robustness. [...] There is still evidence of the health benefits, particularly for coronary heart disease, but it is certainly true that the concerns about how robust the methodology is and whether there are other confounding factors has strengthened considerably, particularly in the last five to 10 years.

25. There is a lack of consensus amongst experts over the health benefits of alcohol, but it is not clear from the current evidence base how the benefits of drinking alcohol at low quantities compare to those of lifelong abstention. In addition, it seems likely that the same purported health benefits could be gained through a healthy lifestyle. Therefore we are sceptical about using the alleged health benefits of alcohol as a basis for daily alcohol guidelines for the general adult population, particularly as these benefits would apply only to men over 40 years and post-menopausal women and the guidelines are aimed at all adults.

Older people

26. As mentioned above, the CHD benefits of alcohol would be predominantly applicable to men over 40 years and post-menopausal women. In June 2011, the Royal College of Psychiatrists published a report on alcohol related harm in the elderly. The report concluded that "because of physiological and metabolic changes associated with ageing, these [Department of Health] 'safe limits' are too high for older people; recent evidence suggests that the upper 'safe limit' for older people is 1.5 units per day or 11 units per week".[62] The Institute of Alcohol Studies was critical of the report[63] and the Royal College of Physicians stated:

there is no arbitrary age when drinking patterns should be advised to change. Individual factors also contribute to the risks of alcohol consumption, including factors such as medication use, co-morbidity and frailty, as well as the physiological changes associated with ageing.

27. The International Scientific Forum on Alcohol Research and Alcohol in Moderation considered that despite suggestions that older people should drink below daily guidelines, "moderate, regular consumption within the guidelines helps protect against cardiovascular disease, cognitive decline and all cause mortality, especially among post menopausal women and men over 40".[65] Sir Ian Gilmore, Royal College of Physicians, considered there was a rationale for setting lower limits for older people, based on their "propensity to fall" as well as the prevalence of other diseases.[66] However, he brought the question back to the issue of complexity:

28. As the Government provides guidelines for specific population groups such as children and pregnant women already, we consider that there could be merit in producing guidelines for older people, balancing evidence of beneficial effects of alcohol with evidence of increased risks. We deal with the issues of guideline complexity further in the next chapter.

Women and alcohol

LOWER GUIDELINES

29. The 1995 report Sensible Drinking recognised the difficulties of providing guidelines for women and alcohol, stating that "the problems of giving accurate advice and information about sensible drinking are nowhere more evident than in this area", explaining that while the broad spectrum of alcohol-related disease and social problems was similar for both sexes, there was a "less secure scientific literature from which to make conclusions about women as compared with men".[68]The report considered physiological differences between men and women and health risks to women such as coronary heart disease, breast cancer and liver disease. The tendency for women to drink less than men at that time was also considered. The report stated that there was, in particular, "very little data linking high levels of consumption in women with a variety of alcohol related diseases".[69] The conclusion was that it was not possible to produce an authoritative statement about women and alcohol as the scientific evidence did not allow that clarity. However, the report stated there was "sufficient indication from the physiology and the patterns of illness for women overall to be advised to drink at lower levels than men".[70]

30. We were interested in exploring whether the basis for the guidelines for women were still considered to be scientifically sound, 16 years after the Sensible Drinking report was published. Dr Marsha Morgan explained that:

Aside from a minority, such as the Association of Small Direct Wine Merchants, who stated that "suggesting 2-3 units of alcohol a day for women or 3-4 alcohol units a day for men without reference to body size [...] is akin to having driving speed limits of 20-30 MPH for women or 30-40 MPH for men",[72] most of the written submissions we received did not challenge the advice that women should be advised to drink less than men, based on health risks. In fact, it appeared that even more evidence had emerged to support this since 1995. For example, Dr Morgan explained that "since the guidelines were last considered in 1995, [...] the major body of evidence has been on the detrimental effect of alcohol and the cancer risk, particularly for breast cancer in women".[73] However, Dr Harding suggested that as women "are exposed to the risk of cardio-vascular diseases" after the menopause, "the benefit that they gain from moderate consumption after the menopause would outweigh any increased risk of cancer".[74]

31. The issue of whether alcohol confers health benefits has already been discussed in paragraph 19. We are content that there is sufficient physiological and epidemiological evidence on health risks to support the retention of lower drinking guidelines for women in general.

DRINKING DURING PREGNANCY

32. The Sensible Drinking report's advice on alcohol and pregnancy was that "to minimise risk to the developing foetus, women who are trying to become pregnant or are at any stage of pregnancy, should not drink more than 1 or 2 units of alcohol once or twice a week, and should avoid episodes of intoxication".[75] In 2006, the UK Chief Medical Officers published revised guidelines taking into account a report commissioned by the Department of Health on the fetal effects of prenatal exposure.[76] The UK Chief Medical Officers advised that "pregnant women or women trying to conceive should avoid drinking alcohol; if they do choose to drink, to minimise the risk to the baby, they should not drink more than one to two units of alcohol once or twice a week and should not get drunk".[77] In England, this was followed by guidance from the National Institute for Health and Clinical Excellence (NICE) in 2007, who advised that the risks of miscarriage in the first three months of pregnancy mean that it is particularly important for a woman not to drink alcohol at all during that period.[78] A slight divergence of advice occurs in Scotland, where the Scottish Chief Medical Officer's current advice on alcohol and pregnancy is that "there is no 'safe' time for drinking alcohol during pregnancy and there is no 'safe' amount".[79]

33. It is generally accepted that high alcohol consumption levels can be harmful during pregnancy.[80] However, the expert views we received suggested that no "safe limit" of alcohol consumption had been identified and that a great deal of uncertainty remains.[81] This scientific uncertainty can be used to produce contrasting but equally probable statements: (i) there is no evidence for a level of risk-free drinking during pregnancy;[82] and (ii) drinking one to two units once or twice a week has not been shown to be harmful.[83] Faced with this uncertainty, the development of policy and provision of definitive advice is difficult[84] and a precautionary approach is clearly attractive to health advice providers. For example, the Royal College of Obstetricians and Gynaecologists highlighted that the positions of its counterparts in the USA, Canada, Australia and New Zealand were, based on factors such as insufficient evidence and a lack of consensus, to encourage abstinence during pregnancy.[85] The UK's Chief Medical Officers (CMOs) reviewed the guidelines for drinking during pregnancy in 2006 and produced updated guidelines that encouraged abstinence but also provided advice for women who chose to drink. We are satisfied that the CMOs have recently reviewed the evidence base and consider that the current guidance adequately balances the scientific uncertainty with a precautionary approach. However, we note that the Scottish CMO has adopted different advice. Consistency of advice across the UK would be desirable.

Sources of scientific advice

34. Sources of scientific advice to Government on alcohol guidelines include the Chief Medical Officers and NICE. We asked Sir Ian Gilmore whether the Government used advice from a wide enough range of sources, and he responded:

The Minister told us that the Department of Health monitors the evidence base "in a variety of ways", both by using its own internal experts and commissioning external advice and support from various bodies.[87] Chris Heffer, Deputy Director, Alcohol and Drugs, Department of Health, described some of the "bespoke" research that had been commissioned by the Department in recent years, including on pricing, licensing and other alcohol policies. However, he noted that "we have not, to my knowledge, done specific research on the guidelines of particular health risks".[88]

35. The Institute of Alcohol Studies suggested that the Government establish a working group, "with representation of health experts, to regularly review the evidence base and provide scientific advice for public health messaging on alcohol".[89] Dr Harding said that although all of the relevant information is published in the literature, "what is needed is a mechanism that brings it all together in a fair and balanced way, so that sensible public health messages can be crafted".[90] He suggested that a review of the relationship between alcohol consumption and disease was "overdue" and recommended the establishment of "a multidisciplinary team, involving experts in the appropriate fields [for example] alcohol misuse, epidemiology, public health, heart disease, dementia, and social science, who are knowledgeable about the current scientific data and who are capable of taking a broad overview".[91] The Department of Health stated that it was "not currently planning a formal review of the guidelines, but would be willing to consider this if it were felt to be useful".[92]

36. When we announced our inquiry into alcohol guidelines in July 2011, there was some media speculation about the possibility of increasing the guideline limits. This appeared to be based on international comparisons with countries that set higher drinking limits in public guidelines as well as the claim that the Royal College of Physicians' 1987 guidelines were "plucked out of the air".[93] However, none of our expert witnesses recommended an increase, and several were in fact adamant that the guidelines should not be increased.[94] Dr Richard Harding also cautioned against relying on international comparisons.[95] When we asked the Minister whether the guidelines should be lowered, she responded: "I do not believe that there is currently any evidence available that would suggest that we ought to alter those guidelines".[96]

37. We have heard sufficient concerns from experts to suggest that a thorough review of the evidence on alcohol and health risks is due. The Department of Health and the devolved health departments should establish a nationwide working group to review the evidence base and use the findings of the review to provide advice on whether the guidelines should be changed. In the meantime, we consider that there does not appear to be sufficient evidence to justify increasing the current drinking guidelines.

29 Department of Health, Sensible Drinking: Report of an inter-departmental working group, 1 December 1995 Back

30 Department of Health, Sensible Drinking: Report of an inter-departmental working group, 1 December 1995 Back

31 Ev 27, paras 1-2 Back

32 Ev 27 [Department of Health] para 1; The Royal College of General Practitioners, Alcohol: a balanced view , 1987; The Royal College of Psychiatrists, Alcohol: our favourite drug, 1986; and The Royal College of Physicians, A Great and Growing Evil: the medical consequences of alcohol abuse, 1987 Back

33 Department of Health, Sensible Drinking: Report of an inter-departmental working group, 1 December 1995, Annex E Back

34 Ev 48 [Dr Richard Harding] para 26 Back

35 Department of Health, Sensible Drinking: Report of an inter-departmental working group, 1 December 1995 Back

36 Department of Health, Sensible Drinking: Report of an inter-departmental working group, 1 December 1995 Back

37 Ev 74 [Institute of Alcohol Studies] para 1 Back

38 Ev w32 [Grampian Alcohol and Drugs Partnerships] para 3.1.2 Back

39 Q 10 Back

40 Department of Health, Sensible Drinking: Report of an inter-departmental working group, 1 December 1995, para 5.5 Back