Course Authors
James H. O'Keefe, M.D., and John H. Lee, M.D.
Dr. O'Keefe is Professor of Medicine, University of Missouri-Kansas City School of Medicine, and Director, Preventive Cardiology Fellowship Program, Mid America Heart Institute, and Dr. Lee is Fellow, Preventive Cardiology, Mid America Heart Institute, Kansas City, MO.
Within the past 12 months, Drs. O'Keefe and Lee report no conflicts of interest.
Estimated course time: 1 hour(s).
Albert Einstein College of Medicine – Montefiore Medical Center designates this enduring material activity for a maximum of 1.0 AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.
In support of improving patient care, this activity has been planned and implemented by Albert Einstein College of Medicine-Montefiore Medical Center and InterMDnet. Albert Einstein College of Medicine – Montefiore Medical Center is jointly accredited by the Accreditation Council for Continuing Medical Education (ACCME), the Accreditation Council for Pharmacy Education (ACPE), and the American Nurses Credentialing Center (ANCC), to provide continuing education for the healthcare team.
Upon completion of this Cyberounds®, you should be able to:
Discuss the health benefits and liabilities of alcohol consumption
Discuss the ideal quantities and drinking patterns for conferring health benefits
Describe the mechanisms of action whereby light to moderate alcohol consumption improves long-term cardiovascular health.
Alcohol consumption is analogous to a double-edged sword with respect to its health effects. Depending upon how it is used, alcohol is capable of cutting more deeply in either direction than perhaps any other single aspect of lifestyle. Light to moderate alcohol consumption (one-half to one drink daily for women and one to two drinks daily for men) is associated with cardio-protective benefits, whereas increasingly excessive consumption results in proportional worsening of outcomes.
Indeed a diverse and growing body of evidence indicates light to moderate alcohol use is associated with reductions in risk for a variety of common maladies including coronary heart disease (CHD), diabetes, dementia and mortality. Additionally, chronic light to moderate alcohol intake is associated with less atherosclerosis, as assessed by coronary angiography,(1) computed tomography (CT) detected coronary calcium(2) (Figure 1) and carotid ultrasound.(3) Light to moderate drinking has also been linked to a decreased prevalence of peripheral arterial disease.(4)
Figure 1. Alcohol and Coronary Calcium.
The likelihood of having extensive coronary calcification on CT scanning was reduced in those who consumed 1 to 2 drinks daily.(2)
On the other end of the spectrum, excessive alcohol intake devastates physical, mental and psychosocial aspects of health, and is the third leading cause of premature death in our society. Because many people look to their personal physician to advise them about their drinking behavior, it is incumbent upon us to be aware of the risks and benefits of alcohol use, the ideal quantities, beverages and patterns of consumption, and patients who might safely consider light to moderate alcohol, as well as those who are probably better off avoiding alcohol.
Moderate alcohol intake is defined as an average of one to two drinks per day for men and one drink per day for women. A drink is considered 12 oz beer, 5 oz of wine, 1.5 oz of 80-proof spirits, or 1 oz of 100-proof spirits, all of which contain approximately 13 to 15 grams of ethanol.
Mechanisms Whereby Alcohol Benefits or Harms Health
Light to moderate alcohol intake appears to confer its cardio-protective effects and other health benefits via two main mechanisms:
- improvements in glucose metabolism and
- increases in circulating high density lipoprotein (HDL) levels.
Accumulating evidence indicates that it is the first mechanism, changes in glucose metabolism, that best explains the powerful bi-directional, dose-related health effects of alcohol. Higher HDL levels are clearly associated with lower rates of CHD and alcohol significantly raises HDL levels.
Alcohol affects HDL in a direct and linear fashion, whereby HDL increases about 5% for each drink consumed on a daily basis(5),(6),(7),(8) (Figure 2). If HDL augmentation was the major factor in alcohol's health benefits, the reductions in CHD would be expected, like HDL, to rise in proportion to the daily dose of alcohol consumed. However, one fact is abundantly clear: though a small to moderate amount of alcohol daily may be good for health, more is definitely not better.
Figure 2. Alcohol Increases HDL Dose Dependently
Alcohol affects HDL in a direct and linear fashion, whereby HDL increases about 5% for each drink consumed on a daily basis.(5),(6),(7),(8)
In a recent cross-sectional study of 3,700 individuals in the general population of Russia, 75% of the men and 45% of the women consumed excessive amounts of alcohol. Although Russia today has a higher mean HDL level than any other country, the rates of CHD and all-cause mortality are significantly higher than those noted in comparable nations in Western Europe or the United States.(9),(10) Thus the benefits of rising HDL levels appear to be overwhelmed by the myriad toxic effects of excessive alcohol intake such as carcinogenicity, predisposition to accidents, high blood pressure and impaired myocardial function, all of which worsen proportionately when the dose of ethanol exceeds about 15 to 20 grams daily.
In contrast to the linear effects of alcohol on HDL, the effects on glucose homeostasis are nonlinear, with benefits at lower doses and harm at higher doses. Tellingly, the interaction between alcohol intake and postprandial glucose follows the same J-shaped relationship that is seen between alcohol and systemic inflammation(11) (Figure 3), and recurrently with alcohol and a wide variety of adverse health outcomes such as myocardial infarction (MI)(12) (Figure 4), non-hemorrhagic stroke<(13) (Figure 5), hypertension, congestive heart failure, dementia and all-cause mortality(14),(15) (Figure 6).
Figure 3. Alcohol and C-reactive Protein Levels.
Alcohol was associated with reduction in C-reactive protein, particularly at 5 to 7 drinks per week.(11) Reproduced with permission.
Figure 4. Alcohol Intake and Risk of MI in Men Following a Healthy Lifestyle.
Moderate alcohol intake (1-2 drinks per day) reduced the rate of myocardial infarction in this group of 8867 middle aged males already following healthy lifestyle recommendations.(12)
Figure 5. Alcohol and Stroke Risk.
Relationship between alcohol and ischemic stroke. This was fully adjusted for the usual stroke factors.(13) Reproduced with permission.
Figure 6. Alcohol and All-cause Mortality.
Reproduced with permission.
The 2007 American Diabetic Association guidelines state that "In individuals with diabetes, light to moderate alcohol intake (1 to 2 drinks per day; 15-30 g alcohol) is associated with a decreased risk of cardiovascular disease, which does not appear to result from an increase in HDL cholesterol."(16) In a recent study, 20 grams of alcohol (approximately 1.5 drinks) when consumed immediately before a meal reduced the postprandial glucose excursion by about one-third in a group of healthy young individuals(17) (Figure 7). Light to moderate alcohol consumption also improves postprandial glucose in both types 1 and 2 diabetic patients(18) (Figure 8).
Figure 7. Pre-Meal Alcohol Reduces Postprandial Glucose.
Alcohol prior to a meal reduced the postprandial glucose excursion by about one-third in a group of healthy young individuals.(17) Wine induced the most significant improvements.
Figure 8. Wine with Meal Reduces Postprandial Glucose in Patients with Type 1 Diabetes.
In this group of Type 1 diabetic patients, wine with the meal (solid black circles), substantially reduced postprandial glucose for the subsequent 12 hours, compared to subjects who drank a non-alcoholic wine placebo (open circles).(18) Reproduced with permission.
Since exaggerated post meal glucose excursions stimulate oxidative stress, inflammation and atherosclerosis, therapies such as low dose alcohol and the traditional Mediterranean diet which improve postprandial glucose are generally anti-inflammatory and cardio-protective.(19) In non-diabetic patients, moderate daily alcohol intake reduces the likelihood of developing type 2 diabetes by 30%(20) (Figure 9) and also reduces the risk of developing the metabolic syndrome.
Figure 9. Alcohol Intake and Incidence of New Type 2 Diabetes.
Reproduced with permission.
Alcohol also increases the levels of adiponectin, a protein hormone secreted by adipocytes which appears to improve lipid and glucose metabolism and increase insulin sensitivity.(21)
Ideal Drinking Patterns and Beverages
Harry Truman, one of the healthiest and long-lived of the American Presidents, started off each day, before his morning walk, with a shot of bourbon whiskey.(22) Although this unconventional drinking habit seems ill-advised, it likely contributed to Truman's health and longevity. Alcohol consumption, like exercise, is most beneficial when done daily and in moderation. On most days, the only alcohol Truman consumed was contained in his morning shot of whiskey.
The ethanol in a drink, rather than other non-alcoholic components of wine, beer or spirits, appears to be the major factor in conferring the health improvements.(5),(23) Red wine has been shown to have higher levels of anti-oxidants compared to white wine and other forms of alcohol.(24) Additionally, wine, more so than beer or spirits, has been associated with improvements in autonomic tone, as measured by heart rate variability.(25) Yet, the emerging scientific consensus suggests that the specific alcoholic beverage is less important with respect to its health effects than the quantity of alcohol consumed and pattern of drinking.(26)
Light to moderate amounts of ethanol, like exercise, will increase insulin sensitivity and glucose metabolism for the ensuing 12 to 24 hours. Accordingly, daily low dose ethanol consumption is associated with better health than less frequent consumption.(5),(23),(27),(28),(29) In a large epidemiologic study, a 37% reduction in CHD was noted among those who drank 5 to 7 days per week compared to those who drank less than once per week.(5) This may reflect the fact that alcohol-induced improvements in insulin sensitivity, HDL cholesterol and inflammation are temporary -- reverting back to baseline within 24 hours.(27)
Some studies demonstrate that the health benefits of alcohol are most apparent when it is consumed before or during a meal(28) and the reduction in postprandial glucose documented with light to moderate drinking lends biologic plausibility to this premise.(8) Indeed, regular light to moderate alcohol consumption with or before the evening meal is a tradition shared by many cultures with exceptionally good health and longevity. This drinking pattern maximizes the health benefits by aligning the alcohol-stimulated insulin sensitizing and glucose lowering effects to coincide with the largest postprandial glucose excursion of the day.
Despite Mark Twain's opinion as regards "Everything in moderation, including moderation," studies indicate that even occasional excessive alcohol intake presents a health threat. Binge drinking (≥5 drinks per drinking day) increases risk of MI, all-cause mortality and other adverse outcomes even in otherwise light drinkers.(5),(28),(29),(30) The MONItoring of trends and determinants in Cardiovascular disease (MONICA) Project reported that male binge drinkers had a two-fold increase risk for acute MI and all-cause mortality compared to those who did not drink at all.(31) MONICA also revealed that men who consumed one or two drinks daily had a 50% reduction in risk of acute MI compared to non-drinkers.
Recommendations Regarding Alcohol Consumption
It is tempting, based on the current wealth of evidence showing remarkably consistent J-shaped associations between alcohol intake and a variety of adverse health outcomes, to recommend small daily doses of alcohol (for example, 1 drink per day) to non-drinkers with or at high risk for CV disease and/or diabetes. Guidelines for sensible drinking developed in England stated: "Middle aged or elderly men and post-menopausal women who drink infrequently or not at all may wish to consider the possibility that light drinking may benefit their health."(26) It might be reasonable for a physician to make this recommendation to patients well known to him or her who have no personal or family history of prior substance abuse, no history of depression or bipolar disorder and who are non-smokers. However, light to moderate drinking cannot be generally recommended in an unselective manner even to patients with CV disease.
Sobering data caution that light to moderate daily alcohol is a slippery slope across which many people cannot safely navigate. Heavy alcohol use is the cause of much distress and morbidity both at the personal and societal levels. Alcohol abuse, the third largest preventable cause of death, is responsible for killing more than 100,000 Americans annually.(32) Recent reports suggest that alcohol abuse and binge drinking may be on the rise, especially among young people.(32) Excess intake increases risks for motor vehicle accidents, stroke, cardiomyopathy, cardiac dysrhythmia, sudden cardiac arrest, suicide, cancer (most notably of the breast and gastrointestinal tract), cirrhosis, fetal alcohol syndrome, sleep apnea and all-cause mortality.(5),(28),(29),(30)
The current American Heart Association guidelines advise individuals not to start drinking if they do not already drink alcohol because it is difficult to predict in which people alcohol abuse might become a problem.(15) Until we have more randomized outcome data, as well as tools for predicting susceptibility to problem drinking, it would seem prudent to encourage physicians and patients to focus on more innocuous interventions to prevent CHD.
"It has long been recognized that the problems with alcohol relate not to the use of a bad thing, but to the abuse of a good thing."
-- Abraham Lincoln