Drinking alcohol has been conclusively linked to many adverse health consequences.
However, the exact relationship between lower levels of alcohol consumption and health outcomes is more complicated.
Despite decades of investigation, whether any level of alcohol intake is "safe" is still hotly debated.
But some studies have demonstrated a so-called J-shaped association between drinking alcohol moderately and longevity.
In other words, a small amount of alcohol might be less dangerous to health than both excessive intake and total abstinence — particularly, it seems, in regard to cardiovascular health.
Is moderation the key?
Other researchers have questioned whether this J-shaped association is a true reflection of reality. The way in which older studies were conducted has been called into question, and without large-scale, long-term studies, it is difficult to paint an accurate picture.
So, to dig a little deeper into this relationship, scientists at Queen's University Belfast in the United Kingdom — led by Andrew Kunzmann — dove into data from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial.
This trial provided access to the detailed information of almost 100,000 participants throughout the United States who were followed for an average of 8.9 years. Their results are published this week in the journal PLOS Medicine.
Across the study, there were 9,559 deaths and 12,763 primary cancers. All individuals took a diet history questionnaire that included information about their drinking habits. Each participant was assigned a group based on alcohol consumption. These included:
- lifetime never drinkers (LN) — no alcohol consumption
- infrequent drinkers (ID) — one or fewer drinks per week
- light drinkers (LD) — one to three drinks per week
- heavy drinkers (HD) — two to three drinks per day
- very heavy drinkers (VHD) — three or more drinks per day
A J-shaped interaction
Again, the team found evidence of a J-shaped interaction between health outcomes and alcohol. Of the groups outlined above, LD had the lowest mortality risk.
This means that those who drank one to three drinks per week had less risk than both those who drank less alcohol each week and those who drank more.
When the scientists investigated lifetime cancer risk, they found a linear relationship between the amount of alcohol consumed and risk; each drink per day increased the risk of cancer.
However, when cancer risk and mortality were analyzed together, LD still had the lowest risk of all groups.
The authors mention certain limitations to the study. For instance, the analysis only included older adults, and there was no way to control for differences in socioeconomic background.
The study authors conclude, "This study provides further insight into the complex relationship between alcohol consumption, cancer incidence, and disease mortality and may help inform public health guidelines."
Kunzmann is quick to note that this study shouldn't be taken as evidence to support the protective effects of drinking in moderation.
Current U.S. alcohol guidelines advise that men drink no more than two drinks each day, and that women drink no more than one per day. The authors hope that these latest findings will help to inform future updates to these guidelines.