In synthesizing these studies, it has been argued that protective effects of alcohol on health have been overestimated and that the association, instead of being causal, is due to the methodological limitations of observational studies. Chikritzhs and colleagues (2015) contend that no protective effects should be assumed in future estimates of alcohol-related burden of disease or in national drinking guidelines. Several areas of potential bias have been identified that could lead to spurious associations, including misclassifying former drinkers as abstainers, residual or unmeasured confounding, and selection biases (Naimi, Brown, Brewer et al. 2005; Fillmore, Stockwell, Chikritzhs et al. 2007; Chikritzhs, Fillmore and Stockwell 2009; Klatsky and Udaltsova 2013; Goulden 2016; Naimi, Stockwell, Zhao et al. 2017). Whether moderate alcohol consumption confers health benefits to current drinkers continues to be a topic of strong debate in the scientific literature (Chikritzhs, Stockwell, Naimi et al. 2015; Mukamal, Clowry, Murray et al. 2016; Britton and Bell 2017; Naimi, Stockwell, Saitz et al. 2017; Rabin 2018).
