While observational epidemiologic studies for many decades have consistently shown that moderate drinkers have a lower risk of cardiovascular diseases than do non-drinkers or heavy drinkers, the specific metabolic effects of alcohol have been little studied. In the present analysis, among almost 10,000 young adults from three population-based cohorts in Finland, associations of alcohol intake with 86 metabolic measures were assessed. Circulating lipids, fatty acids and metabolites were quantified by high-throughput nuclear magnetic resonance metabolomics and biochemical assays. The investigators found that alcohol consumption was associated with a complex metabolic signature, including aberrations in multiple biomarkers for reduced as well as elevated cardiometabolic risk; many factors showed different associations according to the estimated amount of alcohol consumed.
Among key associations found for greater alcohol intake were increases in HDL-cholesterol and its subclasses, decreases in LDL size, an increase in monounsaturated fatty acids and a decrease in omega-6 fatty acids, and lower concentrations of glutamine and citrate. For unexplained reasons, the changes in fatty acids from alcohol in this study were similar to those occurring following the administration of canola oil in other research. Some Forum reviewers pointed out that the analyses were not theory driven, and should only be used to generate hypotheses that would need to be tested in future experiments. As stated by one reviewer, the major contribution from this paper could be that it ignites the interest for experimental studies and provides new variables to be evaluated in prospective studies. In any case, the findings of this study provide valuable clues to the biologic effects on health, both favorable and adverse, related to alcohol consumption.
While not discussed by the authors, Forum members considered that the results of this paper might also be useful in providing a new approach for judging the level of alcohol intake of individuals in epidemiologic studies. At present, alcohol intake is judged almost exclusively from self-reports by subjects. Previous attempts designed to identify subjects more likely to be under-reporting their intake have shown that they may sharpen relations between estimated intake and health outcomes. Forum members believe that approaches that identify sources of bias for self-reported data, whether based on genetic, behavioral, physiological, or other information (preferably on all), might allow epidemiologists to have more precise and accurate information on alcohol intake when relating such to disease outcomes. A new approach for providing more accurate and unbiased estimates of alcohol intake is suggested by this excellent analysis.
Reference: Würtz P, Cook S, Wang Q, Tiainen M, Tynkkynen T, Kangas AJ, et al. Metabolic profiling of alcohol consumption in 9778 young adults. Int J Epidemiol 2016; pre-publication: doi: 0.1093/ije/dyw175