Modest alcohol consumption decreases the risk of non-alcoholic fatty liver disease: a meta-analysis of 43 175 individuals

SILVIA C. SOOKOIAN; GUSTAVO O. CASTAÑO; CARLOS J. PIROLA

GUT - AN INTERNATIONAL JOURNAL OF GASTROENTEOROLOGY AND HEPATOLOGY

B M J PUBLISHING GROUP

Lugar: Londres; Año: 2014 vol. 63 p. 530 - 532

0017-5749

Epidemiological studies suggested that the prevalence and the disease severity of nonalcoholic fatty liver disease (NAFLD) are lower for people who drink modest amounts of alcohol than those who are abstainers. Nevertheless, the evidence is still inconclusive because some recently published studies [1] showed that modest alcohol consumption increases hepatic fat without increasing the risk of advanced fibrosis. Remarkably, we also found in the Argentinean population that modest alcohol consumption (MAC) has a beneficial effect not only on NAFLD but on various components of the metabolic syndrome, including body mass index (BMI), blood pressure, HOMA-IR, and C-reactive protein levels. Accordingly, NAFLD and NASH prevalence, liver enzymes, and inflammatory markers were also lower in subjects who took modest amounts of alcohol than those who are abstainers (Table 1). Hence, we propose to take advantage of meta-analysis to estimate from published data the effect of MAC on the odds of having NAFLD to give a quantitative assessment of this relationship. Thus, we addressed two different relevant clinical questions. Is MAC associated with lower prevalence of NAFLD? Data regarding MAC and NAFLD was extracted from eight heterogeneous (I2:80.7, p<0.0001) studies [1-8] that were meta-analyzed along with our own data; the analysis included 43,175 adult individuals (30,791 non drinkers and 12,384 modest drinkers). The analysis showed that MAC was associated with a significant protection from the odds of having NAFLD in both fixed (OR 0.688, 95% CI: 0.646?0.733, p<10−8) and random models (OR 0.684, 95% CI: 0.580?0.806, p<10−5), regardless of studies being general population or hospital-based ones (Figure 1). This beneficial effect seems to be independent of covariates such as BMI (meta-regression analysis showed that this association was independent of BMI (slope= 0.01, p<0.44), but is much influenced by sex. Of note, among women (n: 12,459), the protective effect of MAC on NAFLD was surprisingly higher (about 53%), when compared with men (about 30%). The female paradox is an interesting finding of our study because, while a large body of evidence suggest that women require less amount of alcohol to cause liver toxicity [9], MAC has a stronger protective effect on NAFLD in women. Is MAC associated with lower prevalence of NASH among those with NAFLD? MAC was found to have a significant protective effect on the development of NASH in both fixed and random model (OR 0.501, 95% CI: 0.340?0.740, p<0.0005), without any evidence of heterogeneity (p: NS, I2: 0), data from 822 patients (550 non drinkers and 272 modest drinkers) diagnosed by liver biopsy in our population and 2 additional studies [2;10]. Thus, NAFLD patients who had MAC were more likely to have simple steatosis as opposed to NASH than abstainer patients. In conclusion, quantitative evidence showed that MAC is associated with a significant protective effect of about 31% on the risk of having NAFLD. Even more remarkable, MAC was associated with an average protective effect of about 50% on the risk of developing an advanced disease stage. Future research agenda still remains open, looking for answers from cohort prospective studies elucidating the exact role of modest alcohol consumption on the natural history of NAFLD. In addition, further exploration in future epidemiological studies should answer the question of whether different kinds of beverages are equally beneficial and are equally able to protect against NAFLD. Meanwhile, the deleterious effects of excess drinking must always be highlighted to NAFLD patients, but they might be allowed to drink low amounts of alcohol, including a narrow window between maximum protection and harm, which is not the same in men and women.