Alcohol Consumption Guidelines: International Discrepancies and Variations
Excessive alcohol intake is regarded as a detriment to health, responsible for 4% of all deaths, and playing a putative role in 60 different diseases . Drinking within the limits, at light-to-moderate amounts, has shown to reduce cardiovascular disease risk and all-cause mortality in a dose-dependent manner [2–4]. The causal nature of this observation is an intense topic of debate, and with the variability in drinking guidelines and low-risk thresholds across the literature, the ambiguity and uncertainty around alcohol and cardiovascular health remains.
We read with great interest the commentary presented by Wise  on a recent study by Wood et al in the Lancet , aimed at characterizing the risk-thresholds for lowest risk of all-cause mortality and cardiovascular disease in current alcohol drinkers. The investigators conducted individual participant-data analysis from 83 prospective studies encompassing 599 912 current drinkers. Alcohol consumption was characterized into eight predefined categories, where 1 unit equaled 8g of pure ethanol. They observed a positive and curvilinear relationship with alcohol consumption, with the lowest risk for all-cause mortality at levels of 100 g/wk. or less. Drinking above the UK and US limits conferred a reduced life expectancy for both genders at age 40, and reducing consumption to 100 g/wk. was associated with an increased life expectancy by 1-2 years at age 40 .
With growing awareness of the adverse effects of alcohol on individual and global health, low-risk consumption guidelines are an important policy consideration. However, due to the wide cross-national variations in maximum consumption allowances, discrepancies in typical serving sizes, variations in standard drink equivalents, and differences in drinking cultures, the understanding and subsequent impact of drinking guidelines in enabling safe-drinking practices could be undervalued by customers [7,8]. Since the introduction of UK’s drinking guidelines, two cross-sectional studies in the UK’s drinking population have found that the majority of the public was aware of the existence of the guidelines, however knowledge of the recommended limits was surprising low , and adherence to them was transient . In addition, only a subset tracked units of alcohol consumed in both studies. For researchers and physicians, the divergence in standard drink sizes could limit the applicability of screening instruments to other countries without adjustment, such as the World Health Organization’s (WHO) Alcohol Use Disorder Test (AUDIT), a tool for primary care physicians to identify harmful patterns of drinking in patients . In addition, there is limited data on the physician demographic regarding their knowledge and understanding of drinking metrics such as standard drinks, low-risk guidelines, and their comfortability in counselling patients on this topic .
Low-risk consumption guidelines have been defined in at least 37 countries . They are commonly reported in standard drinks (SD), which are further expressed in ounces of beer, wine, and spirits. The AUDIT and WHO assume 1 SD to be 10g of pure ethanol, with a recommendation to consume ≤2 SD per day with at least 2 non-drinking days per week . In the UK, 1 SD equates to 8g of pure ethanol, with a recommendation to not exceed 14 SD per week, spread evenly over 3 days or more . The US Dietary Guidelines define 1 SD to contain 14g of pure ethanol, 40% larger than the WHO limit, with a recommendation to consume ≤1 SD per day for women and ≤2 SD for men . In addition, the American Heart Association , American Society of Hypertension , American Stroke Association , and the American Diabetes Association  define their own drinking guidelines, in the realm of 1-2 SD per day across the societies. Even after epidemiological agreement of a light-to-moderate drinking pattern to confer the lowest risk, forming guidelines often involve judgement based on a myriad of other factors, where variability is inevitable.
The authors should be commended for their important addition to the literature , and Wise for an insightful comment . Taken together, the study by Wood et al  substantially adds to the body of alcohol and cardiovascular health literature by defining low-risk drinking thresholds.
1 O’Keefe EL, Di Nicolantonio JJ, O’Keefe JH, et al. Alcohol and CV Health: Jekyll and Hyde J-Curves. Prog Cardiovasc Dis 16 February 2018. doi:10.1016/j.pcad.2018.02.001
2 Haseeb S, Alexander B, Baranchuk A. Wine and Cardiovascular Health: A Comprehensive Review. Circulation 2017;136:1434–48. doi:10.1161/CIRCULATIONAHA.117.030387
3 Baranchuk A, Haseeb S, Alexander B. Wine Consumption and Cardiovascular Health: An Expert Opinion. International Society of Cardiovascular Pharmacotherapy 2018.http://www.iscpcardio.org/expert-opinions/wine-consumption-and-cardiovas... (accessed 1 May 2018).
4 Rehm J, Roerecke M. Cardiovascular effects of alcohol consumption. Trends Cardiovasc Med 2017;27:534–8. doi:10.1016/j.tcm.2017.06.002
5 Wise J. Study backs alcohol UK limit of six glasses of wine a week. BMJ 2018;361:k1630. doi:10.1136/bmj.k1630
6 Wood AM, Kaptoge S, Butterworth AS, et al. Risk thresholds for alcohol consumption: combined analysis of individual-participant data for 599 912 current drinkers in 83 prospective studies. The Lancet 2018;391:1513–23. doi:10.1016/S0140-6736(18)30134-X
7 Mäkelä P, Montonen M. Low-risk drinking guidelines to reduce alcohol-related harm: Delphi survey to explore aspects ‘beyond epidemiology’. Addict Res Theory 2018;0:1–11. doi:10.1080/16066359.2018.1434155
8 Baranchuk A, Alexander B, Haseeb S. Drinking red wine is good for you — or maybe not. The Washington Post. 2017.https://www.washingtonpost.com/national/health-science/drinking-red-wine... (accessed 1 May 2018).
9 Rosenberg G, Bauld L, Hooper L, et al. New national alcohol guidelines in the UK: public awareness, understanding and behavioural intentions. J Public Health:1–8. doi:10.1093/pubmed/fdx126
10 Stevely AK, Buykx P, Brown J, et al. Exposure to revised drinking guidelines and ‘COM-B’ determinants of behaviour change: descriptive analysis of a monthly cross-sectional survey in England. BMC Public Health 2018;18:251. doi:10.1186/s12889-018-5129-y
11 Higgins-Biddle JC, Babor TF. A review of the Alcohol Use Disorders Identification Test (AUDIT), AUDIT-C, and USAUDIT for screening in the United States: Past issues and future directions. Am J Drug Alcohol Abuse 2018;0:1–9. doi:10.1080/00952990.2018.1456545
12 Haseeb S, Alexander B, Baranchuk A. Response by Haseeb et al to Letter Regarding Article, “Wine and Cardiovascular Health: A Comprehensive Review”. Circulation 2018;137:1880–1. doi:10.1161/CIRCULATIONAHA.117.033086
13 Kalinowski A, Humphreys K. Governmental standard drink definitions and low-risk alcohol consumption guidelines in 37 countries. Addiction 2016;111:1293–8. doi:10.1111/add.13341
14 Babor TF, Higgins-Biddle JC. Brief intervention for hazardous and harmful drinking: a manual for use in primary care. World Health Organization. 2001.http://apps.who.int/iris/bitstream/10665/67210/1/WHO_MSD_MSB_01.6b.pdf
15 Department of Health. UK chief medical officers’ alcohol guidelines review: summary of the proposed new guidelines. 2016.https://assets.publishing.service.gov.uk/government/uploads/system/uploa...
16 US Department of Health and Human Services. Dietary Guidelines for Americans 2015–2020. New York, NY: Skyhorse Publishing Inc; 2015.
17 American Heart Association. Alcohol and Heart Health. 2015.http://www.heart.org/HEARTORG/HealthyLiving/HealthyEating/Nutrition/Alco... (accessed 1 Mar 2018).
18 Hypertension ASo. My blood pressure guide - HTN risks. Steps Blood Press. Control Am. Soc. Hypertens. 2012.http://www.ashus. org/ASH-Patient-Portal/Get-Information/HTN-Risks.aspx.
19 Furie KL, Kasner SE, Adams RJ, et al. Guidelines for the Prevention of Stroke in Patients With Stroke or Transient Ischemic Attack: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association. Stroke 2011;42:227–76. doi:10.1161/STR.0b013e3181f7d043
20 American Diabetes Association. Food & Fitness - Alcohol. Food Fit. Am. Diabetes Assoc. 2013.http://www.diabetes.org/food-and-fitness/food/what-can-i-eat/making-heal...
Competing interests: No competing interests