Alcohol: the good, the bad, and the ugly.

Alcoholic beverages play an important role in modern Western society. In addition to their effects on health, they have profound socioeconomic implications. In 1999, approximately $116 billion was spent by consumers in the United States on alcoholic drinks. (1) Absenteeism and decreased productivity due to hangovers cost businesses and employers $148 billion annually. (2) In addition, various epidemiologic studies document that approximately half of the population between 12 and 20 years of age, slightly more than half of the population over the age of 21, (1) and as many as 79% of adults over the age of 65 consume alcohol on a regular basis. (3)

A substantial body of knowledge is emerging on the interaction between alcohol and the development and expression of a number of diseases, including cardiovascular diseases, cerebrovascular diseases, diabetes mellitus, gastrointestinal and liver diseases. (4) Our understanding of the effect of alcohol on various body systems and homeostasis has significantly increased over the past few years. It is important, however, to emphasize that most of the present research data is plagued by at least three major limitations which curtail our ability to draw firm conclusions on the relationship between alcohol consumption and various diseases.

First and foremost, the majority of available studies are either observational, epidemiologic, or case-control in nature. It is not possible, based on these studies, to determine with any degree of certainty whether an elicited relationship between alcohol consumption and diseases is actually a causal relationship, or whether the observed relationship is due to some other common denominator that had not been taken into account when the data was collected. Many of the apparent beneficial effects of alcohol on, for instance, cardiovascular diseases, may not be directly due to the alcohol consumption per se, but may be due to differences in lifestyle between those who consume alcohol in moderation and those who either do not consume alcohol at all or those who abuse it.

Differences in socioeconomic conditions, amount of physical exercise, nutritional intake, body weight index, cigarette smoking, recreational drug use, family history, and accessibility to medical care may explain some of the beneficial effects associated with moderate alcohol intake. It is also possible that those who consume alcohol in moderation and are able to maintain this level of intake have a different genetic makeup than those who either do not consume alcohol at all, or those who abuse it. This difference in genetic makeup, and not the absolute amount of alcohol intake, may be responsible for the observed differences between moderate alcohol consumers, abstainers, and alcohol abusers. This genetic difference also may be responsible for different rates of alcohol metabolism in different people. Although well-designed and conducted randomized double-blind placebo-controlled studies may provide the answer to this question, it is neither ethically permissible, nor morally justifiable to conduct such studies.

Differences in psychological makeup, and not actual alcohol intake, also may be responsible for many of the detrimental effects of drinking, especially binge drinking. Perceived invulnerability may be the trigger to binge drinking and other risky behavior. This may explain why young people are more likely to drive while intoxicated than older people. (5) and why college athletes consume alcohol more frequently than nonathletes, even though athletes are exposed to more alcohol prevention programs and should be more motivated than nonathletes to abstain from binge drinking. (6) This also may explain the findings that binge drinking is associated with an increased rate of unintended pregnancy, and that binge drinkers are more likely to drive after drinking than nonbinge drinkers. (7) About one third of high school students have ridden in a car with a driver who has been drinking, (8) and binge drinkers are more likely to be tobacco or marijuana users. (9) It therefore becomes very difficult to attribute changes in mortality and morbidity to just binge drinking in the presence of so many other factors.

The second major limiting factor relates to the quantification of alcohol consumption. There is no consensus as to how to best quantify alcohol consumption. Most studies rely on self-report by the patient. This has questionable reliability and validity. (10,11) Furthermore, alcohol consumption often varies from day to day, and the rate of alcohol metabolism may vary from individual to individual. Without being able to define a dose-response effect, it is difficult to establish the relationship between alcohol and various disease states. Although a U-shaped or J-shaped curve has been described in many instances, the lack of a valid reproducible instrument to quantify the actual alcohol intake greatly dilutes the importance of these findings, and makes it very difficult to pool the data from several studies in a meta-analysis. The impact of most of these studies is therefore quite limited.

Some alcoholic drinks also contain substances that may have deleterious or beneficial effects. Some of these substances are known, others are not. Antioxidants, for instance, are present in many wines. Is it the alcohol or the antioxidant that is associated with beneficial effects when taken in moderation? Homemade wines, beers and spirits, and fortified wines add totally different dimensions that further cloud the issue of the effects of alcohol. The exact nature of the alcoholic drink consumed is rarely reported in most studies. Besides, more than one type of alcohol is often consumed. Ideally all these variables should be taken into consideration, and cause us to interpret findings with caution.

The third major limiting factor of many of these studies is the method used to establish a diagnosis of the various associated diseases. Different studies use different criteria to determine whether a disease is present or not. These range from self-reporting by the patient to histopathological evidence. This lack of uniformity makes it difficult to integrate findings from different studies to reach a significant conclusion.

Notwithstanding these limitations, the overarching conclusion is that although alcohol intake in moderation could be beneficial, especially as far as cardiovascular diseases are concerned, alcohol abuse and binge drinking are detrimental. It behooves health care professionals to educate the community about the deleterious effects of alcohol abuse and especially binge drinking. In this respect, it is disappointing to note that recent studies have documented an increase in reported binge-drinking episodes, (7) and that the majority of binge drinkers are not advised by their health care professionals to reduce their alcohol consumption. (12)

In this CME section, we have attempted to include a wide and representative variety of research to allow readers to draw their own conclusions. Exhaustive literature searches were performed on each topic. From the pool of articles reviewed, only the most methodologically sound studies were included. In areas where the research methodology was weak, we have picked the best possible studies. We hope that this will provide readers with the most timely and accurate information possible.

No one can earn a million dollars honestly.
--William Jennings Bryan

Accepted October 18, 2004.

Please see "Alcohol on Trial: The Evidence" on page 34 of this issue.

References

1. Foster SE, Vaughan RD, Foster WH, et al. Alcohol consumption and expenditures for underage and adult excessive drinking. JAMA 2003;289:989-995.

2. Wiese JG, Shlipak MG, Browner WS. The alcohol hangover. Ann Intern Med 2000;132:897-902.

3. Moore AA, Hays RD, Greendale GA, et al. Drinking habits among older persons: findings from the NHANES I Epidemiological Followup Study (1982-1984). National Health and Nutrition Examination Survey. J Am Geriatr Soc 1999;47:412-416.

4. Rehm J, Room R, Graham K, et al. The relationship of average volume of alcohol consumption and patterns of drinking to burden of disease: an overview. Addiction 2003;98:1209-1228.

5. Johnson FW, Gruenewald PJ, Treno AJ. Age-related differences in risks of drinking and driving in gender and ethnic groups. Alcohol Clin Exp Res 1998;22:2013-2022.

6. Nelson TF, Wechsler H. Alcohol and college athletes. Med Sci Sports Exer 2001;33:43-47.

7. Naimi TS, Brewer RD, Mokdad A, et al. Binge drinking among US adults. JAMA 2003;289:70-75.

8. Grunbaum JA, Kann L, Kinchen SA, et al. Youth risk behavior surveillance--United States, 2001. J Sch Health 2002;72:313-328.

9. Curry SJ, Ludman E, Grothaus L, et al. At-risk drinking among patients making routine primary care visits. Prev Med 2000;31:595-602.

10. Del Boca FK, Noll JA. Truth or consequences: the validity of self-report data in health services research on addictions. Addiction 2000;95 (supp 3):S347-S360.

11. Sommers MS, Dyehouse JM, Howe SR, et al. Validity of self-reported alcohol consumption in nondependent drinkers with unintentional injuries. Alcohol Clin Exp Res 2000;24:1406-1413.

12. Denny CH, Serdula MK, Holtzman D, et al. Physician advice about smoking and drinking: are US adults being informed? Am J Prev Med 2003;24:71-74.

Ronald C. Hamdy, MD, and Melissa McManama Aukerman, MS

From the James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, and the Department of Kinesiology, Pennsylvania State University, University Park, PA.

Reprint requests to Melissa McManama Aukerman, MS, Department of Kinesiology, Pennsylvania State University, 275 Recreation Building, University Park, PA 16802. Email: [e-mail]