guest post by April wilson smith, master of public health
A study published in August in The Lancet, one of the world’s most prestigious medical journals, surveyed data from 195 countries on alcohol consumption and health risks, and concluded that “The level of alcohol consumption that minimized harm across health outcomes was zero standard drinks per week.”
For those of us who are concerned enough about our health to use nutritional software to monitor our diets, that is important news. While some of us abstain entirely, many of us consume some amount of alcohol. Some of us have favored red wine for the health benefits it has long been reported to have in reducing risk of cardiovascular disease. Should we rethink our alcohol consumption based on this new study?
The article, entitled “Alcohol use and burden for 195 countries and territories, 1990 – 2016: a systematic analysis for the Global Burden of Disease Study 2016” analyzes the results of almost 592 observational studies on alcohol use and disease, and used 694 sources of data to estimate levels of alcohol consumption.
When attempting to apply the results of a study like this to one’s own personal health decisions, there are several important factors to consider.
First, observational studies look at data that occurs naturally in a population: it studies what people are doing without intervention from researchers. This is very different from a clinical trial, in which researchers assign one group to modify their behavior in some way (such as taking an investigational medication or changing their diet) and another group (the control group) to do what they would do under normal circumstances. When deciding if a drug is safe, researchers have to go through many levels of clinical trials in which other factors about a person’s health (called confounders) are accounted for, so that to the extent possible the only thing that is being measured is the effect of the new drug on the research subject. In the case of alcohol consumption, a clinical trial would have some participants drink no alcohol, others drink a small amount, others drink more, and then analyze their health outcomes over a long period of time. The research subjects would be the same in every other respect other than their alcohol consumption, in as much as possible. They would be from the same country, of the same sex or equally balanced, have the same starting point for health risks, including other health indicators such as obesity and smoking status, and also have approximately the same socioeconomic status and access to health care. Their alcohol consumption would have to be accurately measured over a long period of time, and if there are two things that we know people rarely report accurately, they are calorie intake and alcohol consumption. For practical reasons as well as ethical ones, this is an impossible study to undertake. So researchers must rely on observational data.
The new study has many advantages, one of them being that it does not rely solely on self-report of alcohol consumption, but looks at alcohol sales as well, and attempts to account for purchases by tourists and consumption of home-brewed beverages. It looked at 23 health outcomes, including cancers. While most Americans have heard that there may be benefits to moderate alcohol consumption for risk of cardiovascular disease, some are unaware that alcohol consumption raises the risk of some cancers. This worldwide study found that the relative risk of developing some cancers went up with the amount of alcohol consumed. They found that alcohol seemed to decrease risk of ischaemic heart disease and diabetes for women over 60 in high socioeconomic status countries, but argued that these risks were offset by the other risks of alcohol consumption, such as cancer, injuries, and infectious diseases. When put together, the risk of death from all causes that could be attributed to alcohol consumption (called attributable risk) went up with the number of drinks consumed, even going from 0 to 1 per day.
That would seem to argue against the now conventional wisdom in North America that a glass of wine with dinner is good for your heart. And even if it’s good for your heart, would you rather put yourself at higher risk of cancer?
Herein lies the problem with trying to apply large observational studies to one’s own diet. At younger ages, the largest causes of alcohol attributable death worldwide were road injuries, self-harm and tuberculosis. This tells us two things: first, that driving drunk and drinking so much that you fall or otherwise hurt yourself are extremely dangerous. You probably already knew that. You may not have known that excessive alcohol use contributes to risk of death from tuberculosis. People who drink too much are both more likely to contract TB and more likely to die of it, due to liver toxicity complications of treatment and lower immune function. However, tuberculosis is much more of a danger in lower socioeconomic status areas of the world than in in the developed world. In the under 50 age range, tuberculosis was the largest cause of alcohol attributable deaths in low socioeconomic status countries.
Alcohol Use Disorders are the primary cause of alcohol attributable deaths in higher socioeconomic status countries for women ages 15-49. For men in that age range in richer countries, transport injuries and Alcohol Use Disorders were the main cause of alcohol attributable deaths. The pattern of drinking that leads to road collisions, injuries and Alcohol Use Disorders is vastly different from one or two glasses of wine with dinner or at a social occasion, so this data does not seem to indicate light drinking for younger people in high socioeconomic status areas is particularly dangerous.
The picture gets a little more blurry after age 50. While drunk driving and falling down stairs while intoxicated remain poor health behaviors, the risk of cancer starts to go up. This is also the age when risk of cardiovascular disease increases, so it’s a time when some may consider light alcohol consumption a health benefit. For ischemic heart disease, researchers found a mildly J shaped curve, meaning that a small amount of alcohol conferred lower risk than zero consumption, but as consumption continued to rise beyond a minimal amount, risk increased. However, as one ages, the risk of cancer increases. Cancers were a large proportion of causes of alcohol-attributable deaths in high socioeconomic status nations for those over 50, at 27.1% for women and 18.9% for men. So should you decrease your cardiovascular risk through other means such as exercise and maintaining a low weight, but minimize your cancer risk by keeping wine off the table?
Again, it’s not so simple. A study of 195 countries can not take into account confounding factors such as environmental quality, poverty, stress, social support structures, access to and quality of healthcare, and patterns of drinking. India, for example, is a culture that has historically frowned on alcohol consumption, and even outlaws alcohol in some states. However, India has high rates of binge drinking, which is much more dangerous due to risk of injuries and catching communicable diseases, than frequent light or moderate drinking. Societal attitudes toward drinking have a powerful effect on drinking patterns, and the most prohibitionist nations also tend to have the highest rates of binge drinking, as opposed to cultures where alcohol consumption in moderation is a normal and accepted part of family and social life, a topic covered extremely well by addiction expert and long term thorn in the side of American advocates of abstinence, Dr. Stanton Peele.
The benefits of alcohol consumption have often been attributed to its role as an aid in relaxation and socializing. If you find socializing in a circle of those who drink moderately relaxing, or you and your adult family members enjoy a glass of wine with the family dinner, then moderate alcohol consumption may be good for your health. If your circle of friends relaxes by binge drinking and driving home, you might find yourself living longer if you choose a different circle or friends or volunteer to be the permanent designated driver and abstain. As the experience of those who never consumed alcohol or once did but gave it up confirms, there are infinite ways to socialize and relax without alcohol, just as there are infinite ways to socialize or relax without marijuana, ice cream, or a jacuzzi.
The results of a study of such a broad population that is unable to control for key confounders are impossible to apply to individual health decisions. However, this study has raised awareness about the contribution of alcohol to cancer risk, which may cause some to do further research into their own personal risk factors. For those who drink enough to put themselves at risk of injury or drunk driving, this study only confirms what they already knew: alcohol is a major risk factor for injury and no one should ever get behind the wheel while under the influence.
Study authors argue that “These results suggest that alcohol control policies might need to be revised worldwide, refocusing efforts to lower overall population-level consumption.” I would argue that this conclusion does not follow from the evidence presented. First, as Peele discusses, prohibitionist policies do not necessarily lead to lower levels of consumption, and often lead to more dangerous patterns of consumption. Second, unsafe patterns of drinking such as binge drinking or Alcohol Use Disorders are to blame for many more deaths than light drinking. Scaring people who drink lightly or occasionally will do nothing to address the health issues of injuries and liver damage that follow from heavy drinking, nor will they address the mental health issues that often drive heavy drinking.
For those of us whose health is our main priority, this study offers little actionable information. If you enjoy a glass of wine or a pint of beer in the context of a healthy lifestyle that involves monitoring your nutrition, exercise, and biometrics, as well as regular medical care and avoiding high risk situations, this study should not cause alarm. If you were already drinking more than recommended limits (which also vary from culture to culture: in the US, no more than 1 drink per day for women and 2 per day for men is recommended; in Canada, it’s no more than 2 drinks a day for women and 3 drinks a day for men), then you should examine your habits, have your liver enzymes tested, and consider if life circumstances are pushing you to drink more than you’d prefer for your long term health. Drinking a little more than one ideally would is often a signal that stress is too high or other coping mechanisms are lacking – both of which can damage your health. There is no magical line that one crosses over and becomes a problem drinker or “alcoholic” (a term that is entirely a social construction, not a medical one): if you’re drinking to numb feelings of stress, anxiety or depression or because you feel pressure from partners or peers to drink, your health will thank you for addressing those issues.
So if you’re entering a four ounce glass of wine in your daily Cronometer Diary as you read this, there is no need for alarm, any more than there would be if you were entering a small piece of dark chocolate. As the saying credited to Paracelsus goes, “The dose makes the poison.” Don’t eat too much, don’t drink too much, and don’t read too much into the popular press hype about the latest medical study.
Citation:
GBD 2016 Alcohol Collaborators. Alcohol use and burden for 195 countries and
territories, 1990-2016: a systematic analysis for the Global Burden of Disease
Study 2016. Lancet. 2018 Sep 22;392(10152):1015-1035.
