Reinforcing the Point that Moderate Alcohol Use Does Not Add to Life Expectancy
It is now understood that the past studies indicating that low levels of alcohol use were protective and modestly extended life were flawed. This has been the case for a few years now; the research noted here is just hammering home that point in a more robust way. The fundamental problem is that people can stop drinking for health reasons, and thus the cohort of abstainers tends to contain more sick individuals with a higher mortality risk than is the case for the moderate intake cohort. Problems of this nature, simple in hindsight but essentially ignored for years, bedevil many areas of epidemiological study. There were very similar issues in studies indicating a protective effect for being moderately overweight in later life, for example.
Studies linking moderate drinking to health benefits suffer from fundamental design flaws. The major issue: Those studies have generally focused on older adults and failed to account for people's lifetime drinking habits. So moderate drinkers were compared with "abstainer" and "occasional drinker" groups that included some older adults who had quit or cut down on drinking because they'd developed any number of health conditions. That makes people who continue to drink look much healthier by comparison. And in this case, he noted, looks are deceiving.
For the analysis, researchers identified 107 published studies that followed people over time and looked at the relationship between drinking habits and longevity. When the researchers combined all the data, it looked like light to moderate drinkers (that is, those who drank between one drink per week and two per day) had a 14% lower risk of dying during the study period compared with abstainers.
Things changed, however, when the investigators did a deeper dive. There were a handful of "higher quality" studies that included people who were relatively young at the outset (younger than 55, on average) and that made sure former and occasional drinkers were not considered "abstainers." In those studies, moderate drinking was not linked to a longer life. Instead, it was the "lower quality" studies (older participants, no distinction between former drinkers and lifelong abstainers) that did link moderate drinking to greater longevity.