1. IntroductionMetabolic syndrome i

1. Introduction
Metabolic syndrome is a widely accepted concept that includes the constellation of various metabolic abnormalities and confers an increased risk for cardiovascular events and death.1 It has become a major problem in public health because the prevalence of metabolic syndrome in adult is around 20–25% all over the world.2 Although there are many therapeutic options for managing metabolic syndrome, lifestyle modification remains the primary therapy for the disease.3
Alcohol consumption is one of the most prevalent lifestyle habits throughout the world. Previous research has suggested that alcohol consumption is an influencing factor for metabolic syndrome. However, available literature on the association between alcohol consumption and metabolic syndrome are inconsistent and controversial, of which the protective, detrimental or J-shaped associations have been reported. Such controversy may be attributed to the complex effects of alcohol consumption on each component of metabolic syndrome.4 and 5
Combined with early epidemiological studies, the real pattern of alcoholic beverages consumption on risk of metabolic syndrome has not been clearly elucidated. An earlier meta-analysis on the association between alcohol consumption and metabolic syndrome is also limited in establishing causality for including only cross-sectional data.6 As a result, the aim of the present meta-analysis is to assess the overall association between alcohol consumption and incident metabolic syndrome and to obtain a causality of the risk.