In a recent study published in BMC Medicine, researchers discuss a 2023 study by Tian et al., which analyzed the J-shaped association between health and the consumption of alcohol, and address important factors to consider when interpreting this association.
Study: The relationship between alcohol consumption and health: J-shaped or less is more? Image Credit: Ievgenii Meyer / Shutterstock.com
What did the 2023 study show?
A 2023 study by a team of scientists from China led by Xia Wang used a large dataset from the National Health Interview Survey conducted between 1997 and 2014.
This data was analyzed to identify an association between light to moderate levels of alcohol consumption, as well as cause-specific and all-cause mortality among the United States population. From this data, the association formed a J-shaped curve, where low levels of alcohol consumption provide certain health benefits; however, after a certain threshold, health risks increase rapidly.
Light to moderate levels and infrequent consumption of alcohol were associated with a reduced risk of influenza, chronic lower respiratory tract diseases, cardiovascular disease, pneumonia, and Alzheimer’s disease. Light to moderate drinking also reduced all-cause mortality and mortality associated with various kidney-related diseases such as diabetes mellitus and nephrosis.
Comparatively, binge drinking or high levels of alcohol consumption was associated with a higher risk of all-cause mortality, accident-related mortality, and cancer. Importantly, J-shaped associations must be interpreted carefully after considering the various factors associated with the study methodology.
In the present study, researchers discuss the various methodological issues to consider while interpreting this J-shaped association between alcohol consumption and disease or mortality risks.
How do lifestyle habits affect the potential benefits of drinking?
The first factor to consider while interpreting J-shaped associations related to alcohol consumption is the definition of the reference group and issues of misclassification, which could lead to abstainer bias and the exclusion of ex-drinkers from the reference group definition. To circumvent this problem, many studies, including the one by Tian et al., used a reference group that comprised only lifetime abstainers.
However, a recent systematic meta-analysis that included over 100 cohort studies with close to half a million participants used lifetime nondrinkers as the reference group. To this end, no protective effects against all-cause mortality were associated with even low levels of alcohol consumption.
While interpreting the J-shaped association between alcohol consumption and health risks, one must also consider reverse causation. Individuals who abstain from drinking might already be in poor health, while those who are active and health conscious might drink in moderation while also following other practices that provide health benefits.
Socioeconomic factors might also be involved, with individuals who are active in the social and familial spheres of life, or have a higher socioeconomic status and better healthcare access, make healthier choices in life and drink in moderation. Each of these factors contribute independently to a lower risk of all-cause mortality.
Is any amount of alcohol healthy?
The beneficial effects of moderate alcohol consumption reported by Tian et al. could encourage alcohol consumption. Given that alcohol is addictive and, among susceptible individuals, even low levels of alcohol intake could lead to dependence, these results could encourage such individuals to drink, thereby leading to drastic consequences.
The theoretical minimal exposure levels of alcohol vary across individuals of different ages and regions, thus posing the problem of defining optimal alcohol consumption levels. The beneficial effects of alcohol consumption might also vary with factors such as age, as recommended alcohol consumption levels for younger individuals are close to zero.
Additionally, the beneficial effects of moderate alcohol consumption, such as those related to cardiovascular disease, might be prominent only among populations and regions where the burden related to cardiovascular disease is high.
The safe alcohol consumption threshold is not very well defined, and the set standards are often difficult to adhere to. Furthermore, the health benefits of moderate alcohol consumption may be negated by the increased risk of esophageal and oral cancers and reduced life expectancy associated with alcohol consumption.
Given that it is difficult to distinguish between the effects of various confounding factors and biases while determining the association between alcohol consumption and health, a Mendelian randomization approach was used to evaluate these correlations.
The results from the Mendelian randomization and another genetic epidemiological study reported that the role of light to moderate levels of alcohol consumption in improved cardiometabolic health was either inconclusive or non-causal. Considering this, the World Health Organization (WHO) recently released a statement that no levels of alcohol consumption can be considered safe or beneficial for health.
The current study discussed pertinent issues related to a previous study that reported a J-shaped association between light to moderate levels of alcohol consumption and health benefits.
Recent studies using genetic epidemiological and Mendelian randomization approaches to examine this association, as well as other meta-analyses, have challenged the J-shaped association between alcohol consumption and health risks. Given the various methodological and social issues associated with this finding, the WHO continues to encourage reduced alcohol consumption.
- Tsai, M. K., Gao, W., & Wen, C. P. (2023). The relationship between alcohol consumption and health: J-shaped or less is more? BMC Medicine 21(228). doi:10.1186/s12916-023-02911-w