The interaction between the dietary inflammatory index and MC4R gene variants on cardiovascular risk factors

Background: Previous studies have shown that the minor allele (C allele) for melanocortin 4 receptor (MC4R) rs17782313, may be associated with incidence of obesity and the risk of cardiovascular diseases (CVDs). Moreover, inflammation caused by the diet has been shown to have, potentially, unfavorable effects on CVD risk. This study used a linear regression model to investigate the interactions between the dietary inflammatory index (DII) and MC4R gene variants on markers of CVD. Methods: This comparative cross-sectional study was conducted on 266 Iranian women with overweight and obesity. A food frequency questionnaire (FFQ) with 147 items was used to assess dietary intakes. Individuals were categorized into three groups based on rs17782313 genotype. Participants were also divided into four groups based on DII score. Results: Higher quartiles of DII were associated with lower levels of high density lipoproteins (HDL) (p = 0.01) and higher levels of triglycerides (TG) (p = 0.04). There was a significant difference between genotypes for insulin (p < 0.001), HOMA index (p < 0.001), total body mineral content (p = 0.03), and bone mineral content (BMC) (p = 0.04). Our findings also showed significant interactions between DII score and rs17782313 polymorphism on total cholesterol, total body mineral content, BMC, soft lean mass (SLM), fat free mass (FFM) (p = 0.03), skeletal muscle mass (SMM), and basal metabolic rate (BMR). Conclusion: Higher DII scores were associated with lower HDL levels and higher TG levels, respectively; whilst significant differences were observed between the genotypes of rs17782313 for insulin and HOMA index, total body mineral content, and BMC. These results highlight that dietary compositions, gene variants, and their interaction, should be considered in CVD risk assessment.