Alcohol and cardiovascular disease
Excessive alcohol intake is associated with an elevated risk of alcoholic liver disease (ALD), heart failure, some cancers, and accidental injury, and is a leading cause of preventable death in industrialized countries. However, extensive research has shown that moderate alcohol intake is associated with health benefits, including less cardiovascular disease, diabetes, hypertension, and lower all-cause mortality.
An understanding of the inverse relationship between alcohol consumption and atherosclerosis was understood as early as 1904. The observation of a lower risk of cardiovascular disease (CVD) in France despite a diet rich in saturated fat was labeled the French Paradox. While much concerning this paradox remains unclear, some have suggested that the higher consumption of red wine in France results in lower CVD. Although the reduced incidence of CVD disease associated with moderate alcohol consumption is well established, many physicians have been wary of promoting the use of alcohol for this benefit considering the many negative effects of excessive alcohol consumption.
- Possible mechanisms of alcohol cardioprotection 1
Debate over research methods 2
- Ex-drinkers versus never-drinkers 2.1
- Studies on possible confounding effects 2.2
- Confirmation of Cardioprotection 2.3
- References 3
- Further reading 4
- External links 5
Possible mechanisms of alcohol cardioprotection
Extensive epidemiological studies have demonstrated the cardioprotective effect of alcohol consumption. However the mechanism by which this occurs is not fully understood. Research has suggested several possible mechanisms, 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.
Debate over research methods
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 Dr. 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.
Dr. Arthur Klatsky noted that the flaw pointed out by Fillmore existed in one of his early studies of alcohol consumption, but that his later studies illustrating a protective effect of moderate alcohol consumption did not contain this flaw. 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.
This question of confusion of abstainers with previously heavy drinkers in epidemiologic studies is overcome with studies showing dose response effects. That is, higher amounts of alcohol consumption seem associated with greater cardiovascular benefit. Cardiology associations recommend that people who are currently nondrinkers should not start drinking alcohol.
Studies on possible confounding effects
Some have suggested the cardioprotective effects of alcohol consumption could be explained by confounding variables. For example moderate drinkers might have more healthful lifestyles, higher economic status, better dietary habits, better healthcare, or higher educational levels, etc. However, when these and other factors are considered, the cardioprotective effects of alcohol are still evident.
Confirmation of Cardioprotection
Multiple studies on moderate alcohol consumption have now reconfirmed earlier suspected cardioprotection findings. A 2006 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 myocardial infarction." 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. A multicenter randomized diet study published in 2013 included over 7000 persons at risk to develop cardiovascular disease, and found that a Mediterranean-diet, including an encouragement to daily wine consumption in habitual drinkers, led to decreased cardiovascular events by about 30%. The study was halted prematurely since the health benefits were so dramatic.
- World Health Organization (2004). Global Status Report on Alcohol 2004 (PDF). Geneva.
- Centers for Disease Control and Prevention (CDC) (September 2004). "Alcohol-attributable deaths and years of potential life lost—United States, 2001". MMWR. Morbidity and Mortality Weekly Report 53 (37): 866–70.
- O'Keefe JH, Bybee KA, Lavie CJ (September 2007). "Alcohol and cardiovascular health: the razor-sharp double-edged sword". Journal of the American College of Cardiology 50 (11): 1009–14.
- Cabot, R.C. (1904). "The relation of alcohol to arterioscleroisis". Journal of the American Medical Association 43: 774–775.
- B. Simini (2000). "Serge Renaud: from French paradox to Cretan miracle". The Lancet 355 (9197): 48.
- Paul E Ronksley, Susan E Brien, Barbara J Turner, Kenneth J Mukamal, William A Ghali "Association of alcohol consumption with selected cardiovascular disease outcomes: a systematic review and meta-analysis" BMJ 2011;342:d671
- Tolstrup Janne, Jensen Majken K, Anne Tjønneland, Overvad Kim, Mukamal Kenneth J, Grønbæk Morten (2006). "Prospective study of alcohol drinking patterns and coronary heart disease in women and men". BMJ 332: 1244–1248.
- Davidson DM (October 1989). "Cardiovascular effects of alcohol". West. J. Med. 151 (4): 430–9.
- Ely SW, Berne RM (March 1992). "Protective effects of adenosine in myocardial ischemia". Circulation 85 (3): 893–904. This paper appears to say nothing about alcohol
- Facchini F, Chen YD, Reaven GM (February 1994). "Light-to-moderate alcohol intake is associated with enhanced insulin sensitivity". Diabetes Care 17 (2): 115–9.
- Langer RD, Criqui MH, Reed DM (March 1992). "Lipoproteins and blood pressure as biological pathways for effect of moderate alcohol consumption on coronary heart disease". Circulation 85 (3): 910–5.
- Mennen LI, Balkau B, Vol S, Caces E, Eschwege E (April 1999). "Fibrinogen: a possible link between alcohol consumption and cardiovascular disease?". Arterioscler Thromb Vasc Biol 19 (4): 887–92.
- Paassilta M, Kervinen K, Rantala AO; et al. (February 1998). "Social alcohol consumption and low Lp(a) lipoprotein concentrations in middle aged Finnish men: population based study". BMJ 316 (7131): 594–5.
- Rimm EB, Williams P, Fosher K, Criqui M, Stampfer MJ (December 1999). "Moderate alcohol intake and lower risk of coronary heart disease: meta-analysis of effects on lipids and haemostatic factors". BMJ 319 (7224): 1523–8.
- Thun MJ, Peto R, Lopez AD; et al. (December 1997). "Alcohol consumption and mortality among middle-aged and elderly U.S. adults". N. Engl. J. Med. 337 (24): 1705–14.
- Zhang QH, Das K, Siddiqui S, Myers AK (April 2000). "Effects of acute, moderate ethanol consumption on human platelet aggregation in platelet-rich plasma and whole blood". Alcohol. Clin. Exp. Res. 24 (4): 528–34.
- Wang Z, Barker TH, Fuller GM (December 1999). "Alcohol at Moderate Levels Decreases Fibrinogen Expression In Vivo and In Vitro". Alcohol Clin Exp Res 23 (12): 1927–32.
- Steinberg D, Pearson TA, Kuller LH (June 1991). "Alcohol and atherosclerosis". Ann. Intern. Med. 114 (11): 967–76.
- Mukamal KJ, Mackey RH, Kuller LH; et al. (July 2007). "Alcohol consumption and lipoprotein subclasses in older adults". J. Clin. Endocrinol. Metab. 92 (7): 2559–66.
- Rimm EB, Klatsky A, Grobbee D, Stampfer MJ (March 1996). "Review of moderate alcohol consumption and reduced risk of coronary heart disease: is the effect due to beer, wine, or spirits". BMJ 312 (7033): 731–6.
- Barefoot JC, Grønbæk M, Feaganes JR, McPherson RS, Williams RB, Siegler IC (August 2002). "Alcoholic beverage preference, diet, and health habits in the UNC Alumni Heart Study". Am J Clin Nutr 76 (2): 466–472.
- Pearson, Thomas A. "Alcohol and Heart Disease." 1996;94:3023-3025"Circulation". Archived from the original on 25 January 2006. Retrieved 2006-01-30.
- Dorn JM, Hovey K, Williams BA, Freudenheim JL, Russell M, Nochajski TH, Trevisan M (May 2007). "Alcohol drinking pattern and non-fatal myocardial infarction in women". Addiction 102 (5): 730–9.
- Fillmore KM, Kerr WC, Stockwell T, Chikritzhs T, Bostrom A (April 2006). "Moderate alcohol use and reduced mortality risk: Systematic error in prospective studies" (PDF). Addict Res Theory 14 (2): 101–132.
- Russell, Sabin (2010-08-28). "UCSF points out flaw in studies tying alcohol to heart health". The San Francisco Chronicle.
- Mukamal KJ, Chiuve SE, Rimm EB (2006). "Alcohol Consumption and Risk for Coronary Heart Disease in Men With Healthy Lifestyles". Arch Intern Med 166 (19): 2145–50.
- Sesso HD, Stampfer MJ, Rosner B, Hennekens CH, Manson JE, Gaziano JM (2000). "Seven-Year Changes in Alcohol Consumption and Subsequent Risk of Cardiovascular Disease in Men". Arch Intern Med 160 (17): 2605–12.
- "Alcohol drinking patterns have different CHD outcomes in men and women". BMJ 332 (7552): 0–c. May 2006.
- Tolstrup J, Jensen MK, Tjønneland A, Overvad K, Mukamal KJ, Grønbaek M (May 2006). "Prospective study of alcohol drinking patterns and coronary heart disease in women and men". BMJ 332 (7552): 1244–8.
- USDA Dietary Guidelines for Americans 2005: Chapter 9 Alcoholic Beverages