Possible Changes to the U.S. Dietary Guidelines for Alcohol
July 9, 2010
Commentary
by Dr. Tim Naimi
The alcohol section of the new Dietary Guidelines Advisory Committee report (PDF) could represent a radical departure from the 2005 Dietary Guidelines1 if its conclusions are reflected in the final Dietary Guideline for alcohol scheduled to come out later this year. The proposed increase in daily drinking guidelines that would be defined as “moderate” drinking, the lack of randomized studies on the health effects of alcohol consumption, and potentially dangerous public health messages are some of the reasons these proposed changes are concerning – and worth your time to submit comments by July 15.
The current Dietary Guidelines for alcohol provides drinking guidelines outlining the safest way to consume alcohol for the full range of the U.S. population that already drinks alcohol: up to 2 drinks per day for men and up to 1 drink per day for women (2/1 daily consumption guidelines). However, the new Advisory Committee report proposes that 2/1 consumption guidelines be based on average, rather than daily, consumption. Furthermore, the report would explicitly define “moderate” drinking as drinking up to 4 drinks per day for men and 3 drinks for women (4/3 daily consumption guidelines), so long as the average limits are not exceeded.
If most drinkers drank on a daily basis, then 2/1 daily guidelines would be identical to the proposed 2/1 average guidelines. But this is not how most people drink in the U.S. For example, among men and women who drink an average of <2/1 drinks, respectively, more than three-quarters consume alcohol only 2-3 days per week or less.2 Therefore, with respect to the proposed guidelines, most persons’ consumption on any given day would not be constrained by the proposed new weekly (i.e. “average”) guideline, but would only be affected by the new daily guideline. So in fact the net effect of the proposed change amounts to an endorsement for most men to consume up to 4 drinks and for most women to consume up to 3 drinks on days they actually consume alcohol.In any event, the proposed change represents a doubling of the daily guideline for men, and a tripling of the daily guideline for women. Although drinking 4 drinks for men and 3 drinks for women falls just short of thresholds that define ‘binge’ drinking and is not generally pathologic, relaxing guidelines that might cause some to increase their drinking to these levels is neither safe nor desirable from a public health perspective. Specifically, drinking at these levels results in impairment-level blood alcohol concentrations (BACs) for most drinkers, including legal intoxication-level BACs (0.08% or greater) for some, particularly women.3 Furthermore, epidemiologic studies confirm that drinking 4/3 drinks (or to BACs typically associated with 4/3 consumption) is associated with increased risk for unintentional injuries, including motor vehicle crashes.4-6 And daily consumption exceeding the current Dietary Guidelines is also associated with chronic disease outcomes such as hypertension and overweight.7 Even among those who consume an average of <2/1 drinks, the report offers no evidence (nor are we aware of any) that drinking 4 or 3 drinks during drinking days is safer for any health outcome compared with consuming fewer drinks.
The current (2005) Dietary Guidelines explicitly discourage anyone from beginning to drink or drinking more frequently on the basis of health considerations.1 But the tone of this new report creates an impression that alcohol consumption is a viable therapeutic option to be considered and/or discussed with one’s physician. To date, however, there have been no (zero) randomized controlled trials (RCTs) of low-dose alcohol and any mortality or morbidity outcome. RCTs are the level of evidence required to approve a new pharmaceutical agent, and should be for an agent that is also a leading health hazard and recognized human carcinogen.8, 9 Furthermore, there is good evidence that existing observational studies of “moderate” drinking are likely confounded in ways that bias results in favor of moderate drinkers.10-12 The bottom line is that reams of consistent observational studies can be consistently wrong and lead to erroneous conclusions with mortal consequences, as in the case of hormone replacement therapy.13, 14
Relaxing guidelines delineating “moderate” drinking is not like recommending someone take more vitamins. Alcohol is the third leading preventable cause of death in the U.S.,15 and causes many net excess deaths even assuming a cardio-protective effect among those with low average consumption.16 In addition, there are risks associated with even low levels of consumption (e.g., breast cancer),17 and others who begin to drink or who increase their consumption may encounter alcohol-related problems or end up drinking excessively. Therefore, in the absence of data from randomized trials and on the basis of practical public health considerations, the proposed change to the Dietary Guidelines is a prescription for ill health and adverse social consequences.