Q: I have gotten mixed messages about the effects of alcohol on the heart. Some articles indicate that alcohol harms the heart while others state that it is good for the heart. Which of these positions is correct?
A: Mixed messages concerning alcohol and the heart are unavoidable because it can have both beneficial and harmful effects.
On the positive side, moderate alcohol use (no more than two drinks a day for men and one drink daily for women) is the most potent lifestyle step possible for raising the level of protective HDL cholesterol.
A number of population studies have shown a significantly lower incidence of heart attacks among moderate drinkers compared with nondrinkers. While the lower risk is partly due to higher HDL, other possible explanations for fewer heart attacks in moderate drinkers are small reduction in the atherogenic LDL cholesterol and an alteration in blood platelet chemistry that reduces the formation of blood clots.
On the other hand, too much alcohol can have a direct toxic effect on the heart muscle, causing alcoholic cardiomyopathy that eventually results in heart failure. High intake of alcohol also can trigger heart rhythm disturbances, especially atrial fibrillation, and has been associated with an increased risk of sudden death due to cardiac causes.
Several drinks a day can raise blood pressure, an increase that directly is related to the amount of alcohol consumed. When coupled with the diminished capacity for blood clotting caused by alcohol, the higher blood pressure is associated with an increased risk of strokes resulting from bleeding into or around the brain. In a relatively small number of genetically susceptible people, moderate alcohol use can substantially raise triglyceride levels, which may increase the danger of a heart attack (and acute pancreatitis) in these individuals.
Finally, excessive alcohol can cause liver disease, and even modest drinking before driving can lead to tragic automobile accidents.
Dr. Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine.