BACKGROUND: Research has long found 'J-shaped' relationships between alcohol consumption and certain health outcomes, indicating a protective effect of moderate consumption. However, methodological limitations in most studies hinder causal inference. This review aimed to identify all observational studies employing improved approaches to mitigate confounding in characterizing alcohol-long-term health relationships, and to qualitatively synthesize their findings.
METHODS: Eligible studies met the above description, were longitudinal (with pre-defined exceptions), discretized alcohol consumption, and were conducted with human populations. MEDLINE, PsycINFO, Embase and SCOPUS were searched in May 2020, yielding 16 published manuscripts reporting on cancer, diabetes, dementia, mental health, cardiovascular health, mortality, HIV seroconversion, and musculoskeletal health. Risk of bias of cohort studies was evaluated using the Newcastle-Ottawa Scale, and a recently developed tool was used for Mendelian Randomization studies.
RESULTS: A variety of functional forms were found, including reverse J/J-shaped relationships for prostate cancer and related mortality, dementia risk, mental health, and certain lipids. However, most outcomes were only evaluated by a single study, and few studies provided information on the role of alcohol consumption pattern.
CONCLUSIONS: More research employing enhanced causal inference methods is urgently required to accurately characterize alcohol-long-term health relationships. Those studies that have been conducted find a variety of linear and non-linear functional forms, with results tending to be discrepant even within specific health outcomes.
TRIAL REGISTRATION: PROSPERO registration number CRD42020185861.
BACKGROUND: Studies evaluating alcohol consumption and cardiovascular diseases have shown inconsistent results.
METHODS: We performed a systematic review of peer-reviewed publications from an extensive query of Ovid MEDLINE, Ovid Embase, Ovid Cochrane Database of Systematic Reviews, Scopus, and Web of Science from database inception to March 2022 for all studies that reported the association between alcohol consumption in terms of quantity (daily or weekly amounts) and type of beverage (wine, beer or spirit) and cardiovascular disease events.
RESULTS: The study population included a total of 1,579,435 individuals based on 56 cohorts from several countries. We found that moderate wine consumption defined as 1-4 drinks per week was associated with a reduction in risk for cardiovascular mortality when compared with beer or spirits. However, higher risk for cardiovascular disease mortality was typically seen with heavier daily or weekly alcohol consumption across all types of beverages.
CONCLUSIONS: It is possible that the observational studies may overestimate the benefits of alcohol for cardiovascular disease outcomes. Although moderate wine consumption is probably associated with low cardiovascular disease events, there are many confounding factors, in particular, lifestyle, genetic, and socioeconomic associations with wine drinking, which likely explain much of the association with wine and reduced cardiovascular disease events. Further prospective study of alcohol and all-cause mortality, including cancer, is needed.
Over the past several decades, the prevalence of cardiovascular disease (CVD) has nearly doubled, and alcohol has played a major role in the incidence of much of it. Alcohol has also been attributed in deaths due to infectious diseases, intentional and unintentional injuries, digestive diseases, and several other non-communicable diseases, including cancer. The economic costs of alcohol-associated health outcomes are significant at the individual as well as the country level. Risks due to alcohol consumption increase for most cardiovascular diseases, including hypertensive heart disease, cardiomyopathy, atrial fibrillation and flutter, and stroke. The widespread message for over 30 years has been to promote the myth that alcohol prolongs life, chiefly by reducing the risk of coronary heart disease (CHD). Lack of universal advice and stringent policy measures have contributed towards increased uptake and easy availability of alcohol. The WHO has called for a 10% relative reduction in the harmful use of alcohol between 2013-2025. However, lack of investment in proven alcohol control strategies, as well as persistence of misinformation and industry interference, have hindered the efforts of public health professionals to make sufficient progress in reducing alcohol related harms and death.