Selected gene – polyunsaturated fatty acid interactions and risk of obesity

Objective: Although there are indications for a regulatory effect of polyunsaturated fatty acids (PUFAs) on the association between single nuclear polymorphisms (SNPs) and the risk of obesity, scientific evidence in humans is still scarce. The present analysis investigates such associations using data on polyunsaturated fatty acids in red blood cell membranes (RBC). Subjects and Methods: Within the second Bavarian Food Consumption Survey (cross-sectional, population-based), 568 adult men and women provided a blood sample. Fatty acid composition of RBC membranes was analyzed by means of gas chromatography. Genotyping was performed for 19 candidate genes associated with obesity, including cytokines, adipokines, neurotransmitters and transcription factors. In addition, plasma interleukin-6 (IL-6) concentrations were analyzed. For the statistical analysis an additive unconditional logistic regression model was chosen. Results: About 20% of the study participants were classified as obese (BMI ≥30kg/m²). Several significant gene-PUFA interactions were found indicating an obesity risk modulatory effect of PUFA by gene variants of interleukin-2 (IL-2), IL-6, IL-18, tumor necrosis factor receptor family member 1B (TNFRSF1B), TNFRSF21, leptin receptor (LEPR) and adiponectin (ADIPOQ). After stratification by genotype, the strongest effects were found for rs2069779 (IL-2) and all PUFA as well as for rs1800795 (IL-6) and linoleic or arachidonic acid. The obesity risk for minor allele carriers significantly decreased with increasing fatty acid content. The PUFA-IL-6 interaction was also reflected in the plasma IL-6 concentrations. Conclusion: These findings give further evidence for obesity risk affecting gene-PUFA interactions. However, the observational nature of the study and its small sample size ask for careful interpretation and replication in a second, independent and larger study.