Observational studies & the health messaging merry-go-round: Moderate alcohol, once “healthy,” now “not so good for you after all”

Carolina Branson, PhD, is an associate editor with HealthNewsReview.org. Her graduate work at the University of Minnesota focused on media studies and health. 

iStock_000029453606_SmallFor years, we’ve been hearing moderate drinking is a health boon. From lowered heart disease risk to increased lifespan, the splashy headlines make for great media fodder. The problem: these stories are based on observational research.

Here at HealthNewsReview.org, we think it’s important to point out the limitations of observational research. We’ve reviewed many such stories, including attention-grabbing coverage that claims eating fiber as a teen reduces the incidence of breast cancer, to vegetarians who eat fish having a lower risk of colon cancer. At first glance, these stories don’t seem to be problematic. What’s the harm of healthy eating habits?

False security for the worried well

Well, for one, such stories may give people a false sense that they are significantly impacting their cancer risk by adopting these behaviors. For example, in our review of the story that claims vegetarians who eat fish have a lower risk of colon cancer, we note: “the story never gives readers an accurate breakdown of the primary limitations of the study, and the statistics used in the story will give readers an inflated sense of the benefits.” Such a story might distract readers from more proven methods of preventing colon cancer such as screening with colonoscopy or fecal occult blood testing — neither of which is mentioned by the coverage.

The case for alcohol is more contentious: not only are the health benefits disputed but there are also some established risks of drinking including an increase in accidents, stroke, and some cancers.

red wine

Studies purporting to show the positive effects of alcohol abound in stories such as these:

8 ways red wine keeps you healthy

Drinking alcohol for your health: 3 to 5 drinks weekly may lower risk of heart attack and heart failure

Compounds found in chocolate, red wine may lower Type 2 diabetes risk

“May lower risk of heart attack?”

“May lower Type 2 diabetes risk?”

Those are cause-and-effect statements that aren’t supported by the existing observational data.

And not surprisingly given those limitations, new research out this week paints a quite different picture:

A little alcohol may not be good for you after all

Is moderate drinking not so good for you after all? 

There’s a gaping hole in the scientific case for moderate drinking

This recent spate of stories is yet another example of the scientific merry-go-round news consumers are subject to, and another illustration of the perils of reporting superficially on observational studies.

Were the abstainers alcoholics?

In a nutshell, the new research claims that many of the studies that showed an association between moderate drinking and longevity or a reduction in heart disease combined people who used to drink but currently abstain and lifelong abstainers into the same group. So, for example, those who used to drink and are currently abstaining may also be sick (one reason for not drinking) or may have suffered from alcoholism. Those factors would make the abstainer group look less healthy in comparison with the drinkers, and would tend to skew the conclusions of such research to suggest that alcohol is healthier than it really is.

As the author of the new study, Tim Stockwell, director of the Center for Addictions Research in British Columbia points out in Bloomberg, “The research on potential health benefits of alcohol needs a more skeptical evaluation, by scientists, journalists, and the public alike”. ‘In fairness to the journals, this is a contested area, and it’s an illustration of how subjective the peer review process is,” he said. “We hope our contribution is to put the skepticism back in there.”

Words to live by.

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