Does Moderate Alcohol Consumption Have a Role in Cardiovascular Disease Prevention?

 

Cardiology Advisor

By Crystal Wong, MD

April 27, 2017

Alcohol Consumption and Cardiovascular Disease

 

Alcohol has long been demonstrated to have toxic effects on the human body, but in recent years clinical data suggest that alcohol consumption may actually confer cardiovascular (CV) health benefits.1

 

The risk-benefit relationship observed between alcohol and CV health may be expressed as a U-shaped curve. Observational data point to better CV outcomes — which encompass CV morbidity and mortality — in people who drink moderate amounts of alcohol compared with nondrinkers. Overall CV health may be improved in moderate drinkers as well.2 On the other hand, heavy alcohol intake clearly increases the risk for coronary artery disease, stroke, and death.1

 

However, whether such a U-shaped curve truly exists has been called into question. “The majority of previous studies have typically looked at whether different levels of alcohol consumption are associated with a higher or lower risk of developing any type of cardiovascular disease,” Steven Bell, PhD, from the University of Cambridge in the United Kingdom, said in an interview with Cardiology Advisor. “However, there are lots of different types of cardiovascular disease, with distinct underlying biology, so it is not necessarily so that alcohol would affect risk of developing them all in the same way.”

 

“Grouping together disorders may therefore obscure subtle differences that may be present across diseases. This is important because it is often cited that drinking a small amount of alcohol may be ‘good for your heart,’ but if this relationship is driven by a handful of diseases, and there is no difference or even an elevated risk for a variety of other disorders, then we are not communicating the full picture so that people can make a better-informed decision about their level of alcohol intake.”

 

In addition, the nondrinking groups that have been studied were often heterogeneous and included occasional drinkers, former drinkers, and never drinkers. Former drinkers have worse CV outcomes than never drinkers, and their inclusion in the nondrinking groups may have diluted any potential benefits associated with lifelong abstention from alcohol.2

 

A Population-Based Study on Alcohol and Cardiovascular Disease

 

In an attempt to clarify some of issues associated with prior studies, Dr Bell and colleagues conducted a large, population-based cohort study evaluating the relationship between alcohol intake and several cardiovascular diseases (CVDs) that are known to arise from different pathophysiological processes.2

 

A total of 114,859 individuals with an incident CVD diagnosis were identified from linked electronic health record data. Drinking status was classified as follows: nondrinker, occasional drinker, former drinker, current moderate drinker, and heavy drinker.2

 

Evaluation of the outcomes for aggregated CVD (eg, all-cause death, coronary heart disease, CVD, and fatal CVD end points) demonstrated a J-shaped relationship, with moderate drinkers at lower risk for adverse outcomes than nondrinkers, former drinkers, and heavy drinkers.2

 

The risk for developing specific CV phenotypes was assessed using moderate drinkers as the standard for comparison. Nondrinkers, occasional drinkers, former drinkers, and heavy drinkers had higher rates of unheralded coronary death, heart failure, and peripheral arterial disease as their first CVD. However, heavy drinkers were less likely to have incident myocardial infarction (hazard ratio [HR], 0.88) and stable angina (HR, 0.93) than moderate drinkers.2

 

Nondrinkers were also more likely than moderate drinkers to experience myocardial infarction (HR, 1.32), ischemic stroke (HR, 1.12), and abdominal aortic aneurysm (HR, 1.32). Heavy drinkers were at higher risk for cardiac arrest (HR, 1.50) and intracranial hemorrhage (HR, 1.37) compared with moderate drinkers.2

 

Are the Benefits of Moderate Alcohol Intake Real?

 

While these results support the view that moderate alcohol intake provides CV health benefits, Dr Bell noted that they are not conclusive. “A definitive answer as to whether moderate drinking truly is protective will not be reached in the absence of evidence from a long-term randomized trial,” he said.

 

Michael H. Criqui, MD, MPH, from the University of California, San Diego, told Cardiology Advisor that one drawback of observational studies is that accounting for confounding factors is typically incomplete. “When people in these observational studies are looked at very carefully, people who are light to moderate drinkers tend to be in much better health beforehand, and tend to have higher levels of physical activity,” he said. “Because this study is not a clinical trial, all the differences between drinkers and nondrinkers cannot be adjusted for.”

 

Dr Criqui also pointed out that several recent observational studies showed no mortality benefit with moderate alcohol intake after adjusting for confounding factors such as health status and amount of exercise.3-5 “These studies have called into question whether or not the beneficial effects of light-to-moderate alcohol consumption are real, and you cannot make a strong claim about them being real until you have a randomized trial.”

 

Conducting a clinical trial to answer the question of whether moderate alcohol consumption is heart-healthy would be virtually impossible, according to Dr Criqui. “You would have to randomize people to light-to-moderate alcohol intake vs no alcohol intake for a long period of time. It would be very difficult to have people adhere to the assigned intervention, and you would not want to randomize teetotalers or people who have a problem with alcohol,” he said. In addition, blinding participants to the intervention would not be feasible.

 

Mendelian randomization studies, which provide more robust and less biased information than observational data, may offer some answers. Studies of this type use variations in genes known to affect alcohol metabolism — and, consequently, alcohol use — in order to examine whether alcohol intake plays a causal role in reducing CVD risk.6,7 “There is no evidence that such genes show any protection for [CVD], and that is the closest we have been able to get to a true experiment,” Dr Criqui said.

 

Although there are practical difficulties in conducting a long-term clinical trial evaluating the effect of alcohol intake on CVD at this time, Dr Bell indicated that researchers are trying to figure out how to make such a trial feasible. Drawing on lessons from nutritional interventions and short-term alcohol administration trials may help in this endeavor. Until clinical trials can be performed, he said, “it is unlikely that either proponents or opponents of the hypothesis that moderate drinking is protective will be willing to concede defeat.”

 

Doctor, Should I Drink Alcohol to Prevent Heart Disease?

 

In the absence of definitive data on the CV benefits of alcohol, both Dr Bell and Dr Criqui agree that clinicians should use a healthy dose of caution when approaching the issue of alcohol consumption with their patients.

 

“I think that advising people who choose to drink, do so in moderation remains sound advice,” Dr Bell said. “I would be very reluctant to encourage that doctors or other health workers recommend nondrinking patients take up drinking as a means of lowering their risk of developing a [CVD], as there are safer and more effective means of doing so. For example, through increasing levels of physical activity, following a healthy diet or quitting smoking.”

 

“This is a viewpoint that is also endorsed by the American Heart Association,” he added.

 

According to Dr Criqui, nondrinkers should not start drinking as a way to improve their health, given the hazards of alcohol abuse. “There have been cases of patients — former drinkers — who hear something about the benefits of alcohol, started drinking again, and now are alcoholic and having great difficulties,” Dr Criqui said. “There is a certain number of people in whom drinking will be devastating and, as a physician, you are not always sure if you are talking to one of those people or not. I think that it is problematic to talk to any person in your practice about the potential benefits of drinking.”

 

Dr Criqui also pointed out that any alcohol consumption increases the risk of some heart and vascular conditions, such as atrial fibrillation and intracranial hemorrhage. “I think it is a very difficult position for a physician to ever recommend light to moderate drinking to a patient at cardiovascular risk. It would be much wiser to recommend drugs to control blood pressure and lipids, and increased physical activity, and to leave the 2-edged sword of alcohol drinking alone.”

 

References

 

1. Fernández-Solà J. Cardiovascular risks and benefits of moderate and heavy alcohol consumption. Nat Rev Cardiol. 2015;12(10):576-587. doi:10.1038/nrcardio.2015.91

 

2. Bell S, Daskalopoulou M, Rapsomaniki E, et al. Association between clinically recorded alcohol consumption and initial presentation of 12 cardiovascular diseases: population based cohort study using linked health records. BMJ. 2017;356:j909. doi 10.1136/bmj.j909

 

3. Muscari A, Bianchi G, Conte C, et al; Pianoro Study Group. No direct survival effect of light to moderate alcohol drinking in community-dwelling older adults. J Am Geriatr Soc. 2015;63(12):2526-2533. doi:10.1111/jgs.13837

 

4. Goulden R. Moderate alcohol consumption is not associated with reduced all-cause mortality. Am J Med. 2016;129(2):180-186.e4. doi:10.1016/j.amjmed.2015.10.013

 

5. Stockwell T, Zhao J, Panwar S, Roemer A, Naimi T, Chikritzhs T. Do “moderate” drinkers have reduced mortality risk? A systematic review and meta-analysis of alcohol consumption and all-cause mortality. J Stud Alcohol Drugs. 2016;77(2):185-198. doi:10.15288/jsad.2016.77.185

 

6. Au Yeung SL, Jiang C, Cheng KK, et al. Moderate alcohol use and cardiovascular disease from Mendelian randomization. PLoS One. 2013;8(7):e68054. doi:10.1371/journal.pone.0068054

 

7. Holmes MV, Dale CE, Zuccolo L, et al; InterAct Consortium. Association between alcohol and cardiovascular disease: Mendelian randomisation analysis based on individual participant data. BMJ. 2014;349:g4164. doi:10.1136/bmj.g4164