How a modern myth arose from multiple layers of conflicts of interest.
While there is no doubt that heavy alcohol use is bad for you, the idea that moderate alcohol use (defined as greater than one drink a day for women and two drinks a day for men) is good for you has grown in popularity over the past century. In this blog, we’ll look at where this idea came from, how multiple layers of conflicts of interest perpetuated it, and what unbiased research has to say about the health effects of moderate drinking.
Humans' relationship with alcohol is long and complicated. Studies of the human genome suggest that people have been ingesting alcohol for millions of years and intentionally fermenting alcoholic beverages for 9,000 years (a full thousand years before bread was invented). Both the potential benefits and risks of alcohol have also been described for thousands of years.
On the positive side, alcohol may have been a safer choice for drinking than water prior to purification efforts. In addition, alcohol has had numerous medical applications (brandy was considered an essential medication in the 1800s as an anesthetic, antiseptic, and stimulant), and more recent research suggests moderate drinking could have benefits for conditions including cardiovascular disease, diabetes, and longevity.
On the negative side, although the clinical term alcoholism only arose in the mid-1800s, the problems of both acute drunkenness and long-term heavy use have also been described for thousands of years. While chronic heavy alcohol use is well-established to cause liver disease, heart failure, and stroke, there is also growing evidence that even moderate alcohol use may increase the risk of certain cancers, including esophageal, breast, and colon cancer.
The idea that moderate drinking may be good for you came from Raymond Pearl, a trailblazing epidemiologist who in a 1924 study found that the relationship of alcohol to health followed a “J” shaped curve, with 1-2 drinks per day being the sweet spot for health benefits. The idea that moderate alcohol use is good for you went largely unchallenged, particularly in the popular press, up until about 5 years ago when a series of studies and reports challenged this status quo including:
Reanalysis of data on the J-shape curve suggests that this association may be spurious and due to other factors (see my blog on the dangers of reading too much into correlations). For example, moderate drinkers tend to engage in other positive health activities and many people practicing complete abstinence were former heavy drinkers. Rigorous studies that account for these confounds have failed to find a specific benefit for moderate drinking.
Several new large studies clearly document the risks and contributions of alcohol use to cancer, suggesting the potential benefits of low to moderate alcohol use are nonexistent for most people although small benefits may be seen based on age (more benefits for older people), gender (more dangerous for males), and ethnicity/geography (more benefits for higher risk of cardiovascular disease as a cause of death). These and other studies have led the World Health Organization to conclude that no level of alcohol consumption is safe for health.
Revelations that funding from the alcohol industry has been associated with biased research studies and reporting, including the premature discontinuation of a $100 million dollar study on alcohol and health that was shown to have serious design flaws and biases.
So why is the “common knowledge” that moderate alcohol is good for you still so common?
Conflicts of interest.
A conflict of interest occurs when an individual’s (or company’s) personal interests may be at odds with other work-related or societal obligations. Regarding research, this conflict of interest can lead to conscious and unconscious decisions that create bias.
Some of the many layers of conflicts of interest we see in “the moderate alcohol is good for you” story include:
The Alcohol Industry
The alcohol industry clearly has a strong profit motive that can override other obligations to the public good. In the case of research, the industry’s desire to grow profit (e.g. use research as a marketing tool) almost always trumps the industry’s desire to learn more about the safety and effectiveness of their product (e.g. use research to better understand reality). Choices made by industry in research that bias results include funding investigators who are friendly to the industry, making study design choices that favor certain outcomes, and not reporting results that contradict marketing goals. This potential bias is true in all industries, including the pharmaceutical industry.
There are a few biases we can see in researchers. The most obvious is financial. This can range from unscrupulous researchers who make a living as tools of certain industries to sincere researchers who are struggling for funding and trying to build their careers. The less obvious culprit is reputational where a researcher may make biased choices in their work (or even fabricate data) in order to write a paper that will advance their reputation and career.
As a case in point, as I was researching this blog, I came across a review article that had very different conclusions from other things that I was reading. Although initially subtle, it appeared to me to be biased towards alcohol and have a goal of sowing doubt. I quickly scrolled to the disclosure statement at the end of the article and found, not surprisingly, that the author was “a consultant for the alcohol industry.” Had this been the only article I looked at, this would have been a very different (and biased) blog!
As with researchers, the media has two main conflicts, both of which tie to their business model.
The first is their need to attract an audience. This leads to a bias to prioritize surprising, sensational (and often outrageous) research that generates enticing headlines. As an example, they know they will get viewers or clicks with “Surprising new superfood will help you lose weight” or “Is a cancer-causing substance in your child’s lunchbox?” no matter how bad the science is. Many reporters also distort and exaggerate real research to create what they see as newsworthy stories. I have personal experience being interviewed for a local TV news show on a “Parkinson’s Breakthrough” where the reporter wanted me to say that a basic science finding at our university was going to cure Parkinson’s. It was clear she had no interest in what I had to say and she ended up cutting 95% of our interview and put what little was left of what I said out of context to make her story.
The second is their need to attract and keep advertisers. While this relates to the size of their audience it may also lead them to NOT report on stories that could be unpopular with advertisers. Notably, research on the dangers of alcohol was more likely to be reported by independent media (e.g. National Public Radio) than media dependent on beer advertisements.
Doctors and other healthcare providers are not above conflicts of interest. Pertinent to the alcohol story, doctors enjoy telling people what they want to hear. Beyond telling patients it is OK to have a few drinks, this can also manifest in overemphasizing the benefits of treatments and minimizing the chances of bad outcomes. An important second conflict of interest is secondary gains from recommending certain treatments (e.g. surgeons who get paid more for more surgeries, doctors who get kickbacks for prescribing certain medications).
We are all prone to believe and prefer stories that support our views and our lifestyles to research that challenges them. Part of the popularity of the “moderate alcohol is good for you narrative” is that many of us enjoy alcohol and this story justifies our choices. We can further reinforce our own wrong views through confirmation bias by purposefully seeking information that supports our ideas and downplaying research that challenges them.
The key take-home lesson from this blog is to watch out for conflicts of interest when reading about research or making health-related decisions. Assume that no one is immune from conscious or unconscious biases. It never hurts to ask “What does this reporter, researcher, doctor, industry…” have to gain by me buying this product or story?
Regarding alcohol, I always encourage readers to draw their own conclusions and do their own searches, but would add that regular, moderate alcohol consumption may not be as good for you as was once thought.