Excessive alcohol intake has been associated with an elevated risk of liver disease

Liver disease

Liver disease is a broad term describing any single number of diseases affecting the liver.-Diseases:* Hepatitis, inflammation of the liver, caused mainly by various viruses but also by some poisons , autoimmunity or hereditary conditions...

, heart failure, some cancer

Cancer

Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...

s, and accidental injury, and is a leading cause of death in industrialized countries. However, research suggests that moderate alcohol intake is associated with some health benefits, among them a decreased risk of cardiovascular disease

Cardiovascular disease

Heart disease or cardiovascular disease are the class of diseases that involve the heart or blood vessels . While the term technically refers to any disease that affects the cardiovascular system , it is usually used to refer to those related to atherosclerosis...

.

An early study of the relationship between alcohol consumption and atherosclerosis

Atherosclerosis

Atherosclerosis is a condition in which an artery wall thickens as a result of the accumulation of fatty materials such as cholesterol...

 was published in 1904. Public awareness of the supposed French paradox

French paradox

The French Paradox is the observation that French people suffer a relatively low incidence of coronary heart disease, despite having a diet relatively rich in saturated fats...

in the early 1990s stimulated increased interest in the subject of alcohol and heart disease.

Processes whereby moderate alcohol consumption might benefit cardiovascular health

Given the epidemiological evidence that moderate drinking reduces heart disease, it becomes important to examine how alcohol might confer its cardiovascular benefits. Research suggests that moderate consumption of alcohol improves cardiovascular health in a number of ways, including the following.

I. Alcohol improves blood lipid profile.

A. It increases HDL ("good") cholesterol.

B. It decreases LDL ("bad") cholesterol.

C. It improves cholesterol (both HDL and LDL) particle size

II. Alcohol decreases thrombosis (blood clotting).

A. It reduces platelet aggregation.

B. It reduces fibrinogen (a blood clotter).

C. It increases fibrinolysis (the process by which clots dissolve).

III. Alcohol acts through additional ways.

A. It reduces coronary artery spasm in response to stress.

B. It increases coronary blood flow.

C. It reduces blood pressure.

D. It reduces blood insulin level.

E. It increases estrogen levels

There is a lack of medical consensus about whether moderate consumption of beer, wine, or distilled spirits has a stronger association with heart disease. Studies suggest that each is effective, with none having a clear advantage. Most researchers now believe that the most important ingredient is the alcohol itself.

The American Heart Association has reported that "More than a dozen prospective studies have demonstrated a consistent, strong, dose-response relation between increasing alcohol consumption and decreasing incidence of CHD (coronary heart disease). The data are similar in men and women in a number of different geographic and ethnic groups. Consumption of one or two drinks per day is associated with a reduction in risk of approximately 30% to 50%".

Heart disease is the largest cause of mortality in the United States and many other countries. Therefore, some physicians have suggested that patients be informed of the potential health benefits of drinking alcohol in moderation, especially if they abstain and alcohol is not contraindicated. Others, however, argue against the practice in fear that it might lead to heavy or abusive alcohol consumption. Heavy drinking is associated with a number of health and safety problems.

Ex-drinkers versus never-drinkers

A logical possibility is that some of the alcohol abstainers in research studies previously drank excessively and had undermined their health, thus explaining their high levels of risk. To test this hypothesis, some studies have excluded all but those who had avoided alcohol for their entire lives. The conclusion remained the same in some studies: moderate drinkers are less likely to suffer heart disease. A paper concludes, "In this population of light to moderate drinkers, alcohol consumption in general was associated with decreased MI [myocardial infarction ] risk in women; however, episodic intoxication was related to a substantial increase in risk."

An analysis by sociologist Kaye Fillmore and colleagues failed to find significant support. Analyzing 54 prospective studies, the authors found that those studies which were free of the potential error (including former drinkers in the abstaining group) did not demonstrate significant cardiac protection from alcohol, although they continued to exhibit a J-shaped relationship in which moderate drinkers were less likely (but not at a statistically significantly level of confidence) to suffer cardiac disease than lifelong abstainers. The instructor of nursing says research is needed that looks at the reasons people abstain, which hers did not do.

Cardiologist Dr. Arthur Klatsky notes that Fillmore's study, which she freely acknowledges proves nothing but only raises questions, is itself seriously flawed. To overcome the inherent weaknesses of all epidemiological studies, even when properly conducted, he calls for a randomized trial in which some subjects are assigned to abstain while others are assigned to drink alcohol in moderation and the health of all is monitored for a period of years.

Lifestyle as a possible confounder

Another possibility is that moderate drinkers have more healthful lifestyles (making them healthier), higher economic status (giving them greater access to better foods or better healthcare), higher educational levels (causing them to be more aware of disease symptoms), etc. However, when these and other factors are considered, the conclusion again remains the same: moderate drinkers are less likely to suffer heart disease.

Tests of alternative hypotheses

A study concluded, "Even in men already at low risk on the basis of body mass index, physical activity, smoking, and diet, moderate alcohol intake is associated with lower risk for MI [myocardial infarction]." Other research also addresses this question.

Another study found that when men increased their alcohol intake from very low to moderate, they significantly reduced their risk of coronary heart disease. The study monitored the health of 18,455 males for a period of seven years.

These and similar studies reduce the possibility that it is not alcohol itself that reduces the risk of cardiovascular disease.

Understanding specifically how alcohol improves cardiovascular health and reduces disease also significantly increases scientific confidence in the health benefits of moderate drinking.

External links

• USDA Dietary Guidelines for Americans 2005: Chapter 9 Alcoholic Beverages