Is apelin gene expression and concentration affected by dietary intakes? A systematic review

Overproduction of apelin in obesity could be one of the last protective defenses before type 2 diabetes develops. To summarize the existing evidence on the association between dietary intake and apelin gene expression and concentration. We systematically searched MEDLINE, EMBASE, and google scholar and hand-searched bibliographies, including peer-reviewed articles with English abstracts, without restriction in publication date, updated until 21 February 2016 that reported the association between dietary intake and apelin gene expression or concentration. From a total of 1075 articles, we identified 12 relevant studies. There were 6 clinical trials in human and 6 studies in animals. Overall, two of three studies conducted in humans showed that calorie-restriction diet in obese subjects decreases apelin concentration. Five animal studies reported that higher intake of fatty acids and eicosapentaenoic acid (EPA) increased apelin expression and concentration. Given the paucity of data available, the heterogeneity of study designs used, and exposures tested, no quantitative meta-analysis was justified. Based on human studies, hypocaloric diet can reduce apelin concentration in obese individuals. In addition, higher intakes of total fatty acids and EPA may increase apelin gene expression and concentration.