Do people who drink alcohol in moderation have a greater risk of early death than people who abstain? For years, a drink or two a day appeared to be linked to health benefits. But recently, scientists pointed out flaws in some of the studies that led to those conclusions, and public health warnings have escalated recently that there may be no safe level of alcohol consumption.
Now, yet another research analysis points toward that newer conclusion – that people who drink moderately do not necessarily live longer than people who abstain. The latest results are important because the researchers delved deep into data about people who previously drank but later quit, possibly due to health problems.
"That makes people who continue to drink look much healthier by comparison," said Tim Stockwell, PhD, lead author of this latest analysis and a scientist with the Canadian Institute for Substance Use Research at the University of Victoria, in a statement.
The findings were published this month in the Journal of Studies on Alcohol and Drugs.
The key to their conclusion that drinking isn't linked to longer life is based yet again on who
For the study, researchers defined "low volume drinking" as having between one drink per week and up to two drinks per day. When researchers carefully excluded people who were former drinkers and only included data for people who were younger than 55 when they joined research studies, the abstainers and low-volume drinkers had similar risks of early death. But when the former drinkers were included in the abstainer group, the low-volume drinkers appeared to have a reduced risk of death.
When researchers define which people are included in a research analysis based on criteria that don't reflect subtle but important population characteristics, the problem is called "selection bias."
"Studies with life-time selection biases may create misleading positive health associations. These biases pervade the field of alcohol epidemiology and can confuse communications about health risks," the authors concluded.
They called for improvements in future research studies to better evaluate drinking levels that may influence health outcomes, and also noted one of their exploratory analyses suggested a need to delve deeper into the effects of other outside variables such as smoking and socioeconomic status.
SOURCES:
Journal of Studies on Alcohol and Drugs: "Why Do Only Some Cohort Studies Find Health Benefits From Low-Volume Alcohol Use? A Systematic Review and Meta-Analysis of Study Characteristics That May Bias Mortality Risk Estimates."
Canadian Institute for Substance Use Research: "The research was wrong: study shows moderate drinking won't lengthen your life."