Genetic variants influence the response of body composition and insulin resistance to dietary monounsaturated fatty acids consumption
Obesity and insulin resistance (IR) control is a requisite for reducing the risk of several non-communicable disease states. Although monounsaturated fatty acids (MUFA) advantageously affect obesity and IR risk, inter-individual variations in the responses of obesity and IR to dietary MUFA have been identified. Single-nucleotide polymorphisms (SNPs) profoundly influence such responsiveness; however, the effects of the interactions between dietary MUFA and genetic factors on obesity and IR have been scarcely tested in intervention studies. The objective of the present research was to investigate the impact of genetic variability on responsiveness of body fat mass and IR measure to a high level of dietary MUFA. In a randomized, crossover, controlled-feeding trial, 124 adults with abdominal obesity consumed one of three oils (20% of total energy) each for six weeks, separated by a four-12 week washout. Oils included two-high-MUFA oils, conventional canola and high-oleic canola, and a low-MUFA high-saturated fatty acid (CONTROL) oil blend. In this study, no significant differences were observed in changes in body weight, fat mass, or measures of glycemic control and IR following the consumption of any of the three treatments. However, results reveal that SNPs within obesity-related genes contributed to shaping the degree of body fat response to dietary MUFA. The consumption of high-MUFA diets induced significant reductions in various regions of fat mass in the LPL rs13702-CC, PPARα rs6008259-AA, and ADIPOQ rs266729-GG carriers compared to the opposing genotypes. Further, the CONTROL diet promoted fat mass reductions in participants possessing the FTO rs9939609-A, APOE4, ADRB2 rs1042714-GG, and LIPC rs6083-GG variants, but not in individuals carrying the other genotypes. SNPs within IR-associated genes were found to modify the response of IR measure to dietary fatty acid modification; improvement in insulin sensitivity measures was observed upon consumption of the CONTROL diet compared to the high-MUFA diets in the homozygotes of either the FABP1 rs2241883-CC or the IRS1 rs7578326-GG genotype compared to corresponding genotypes. These findings advance knowledge of the inherited basis by which alleviation of obesity and IR may be achieved in response to dietary fatty acid modification, hence launching an important step towards an era of personalized nutrition.