Alcohol consumption and metabolic syndrome: Clinical and epidemiological impact on liver disease.

Alcohol use and the metabolic syndrome are highly prevalent in the population and frequently co-exist. Both are implicated in a large range of health problems, including chronic liver disease, hepatocellular carcinoma, and liver-related outcomes. Studies have yielded mixed results regarding the effects of mild-moderate alcohol consumption on the risk of metabolic syndrome and fatty liver disease, possibly due to methodological differences. The few available prospective studies indicated that mild-moderate alcohol use had harmful effects on liver-related outcomes. This conclusion was substantiated by systems biology analyses suggesting that alcohol may have a common effect in the systemic and multiorgan metabolic syndrome and fatty liver disease, potentiating an already existing dysregulation of common vital homeostatic pathways. Alcohol and metabolic factors are independently and jointly associated with liver-related outcomes. Indeed, metabolic syndrome increases the risk of liver-related outcomes, regardless of the alcohol intake level. Moreover, the components of metabolic syndrome appear to have additive effects on the risk of liver-related outcomes. A number of population studies have implied that measures of central/abdominal obesity, such as the waist-to-hip ratio, can predict liver-related outcomes more accurately than body mass index, also among individuals who consume harmful quantities of alcohol. Many studies even point to synergistic interactions for liver-related outcomes between harmful alcohol use and many metabolic components. This accumulating evidence showing independent, combined, and modifying effects of alcohol and metabolic factors on the onset and progression of chronic liver disease highlights the multifactorial background of liver disease in the population. The evidence suggests that more holistic approaches could be useful for risk prediction and for diagnostics and treatment planning.