Genetic Variation in the Beta 3-Adrenoreceptor Gene (Trp64Arg Polymorphism) and Its Influence on Anthropometric Parameters and Insulin Resistance Under a High Monounsaturated versus a High Polyunsaturated Fat Hypocaloric Diet

Abstract

Objective: The aim of our study was to investigate the role of Trp64Arg polymorphism of the beta 3-adrenergic receptor (beta 3-AR) gene on metabolic changes and weight loss secondary to a high monounsaturated fat versus a high polyunsaturated fat hypocaloric diet in obese subjects. Material and Methods: A population of 260 obese subjects was analyzed. In the basal visit, patients were randomly allocated for 3 months to either diet M (high monounsaturated fat hypocaloric diet) or diet P (high polyunsaturated fat hypocaloric diet). Results: There were no significant differences between the positive effects (on weight, body mass index, waist circumference, fat mass) in either genotype group with both diets. With diet P and in genotype Trp64Trp, glucose levels (-6.7 ± 12.1 vs. -1.2 ± 2.2 mg/dl; p < 0.05), total cholesterol (-11.2 ± 8.1 vs. -1.0 ± 7.1 mg/dl; p < 0.05), low-density lipoprotein (LDL) cholesterol (-9.7 ± 10.1 vs. -2.2 ± 8.1 mg/dl; p < 0.05), triglycerides (-11.7 ± 13.1 vs. +1.7 ± 10.3 mg/dl; p < 0.05), homeostasis model assessment for insulin resistance (HOMA-R; -0.7 ± 1.1 vs. -0.3 ± 2.1 units; p < 0.05) and insulin levels (-1.8 ± 4.6 vs. -1.0 ± 9.1 mIU/l; p < 0.05) decreased. Conclusion: The metabolic effect of weight reduction by the two hypocaloric diets is greatest in subjects with the normal homozygous beta 3-AR gene. Improvements in total cholesterol, LDL cholesterol, triglyceride, glucose, insulin and HOMA-R levels were better than in the heterozygous group.