Glucokinase regulatory protein genetic variant interacts with omega-3 PUFA to influence insulin resistance and inflammation in metabolic syndrome.

UNLABELLED: Glucokinase Regulatory Protein (GCKR) plays a central role regulating both hepatic triglyceride and glucose metabolism. Fatty acids are key metabolic regulators, which interact with genetic factors and influence glucose metabolism and other metabolic traits. Omega-3 polyunsaturated fatty acids (n-3 PUFA) have been of considerable interest, due to their potential to reduce metabolic syndrome (MetS) risk. OBJECTIVE: To examine whether genetic variability at the GCKR gene locus was associated with the degree of insulin resistance, plasma concentrations of C-reactive protein (CRP) and n-3 PUFA in MetS subjects. DESIGN: Homeostasis model assessment of insulin resistance (HOMA-IR), HOMA-B, plasma concentrations of C-peptide, CRP, fatty acid composition and the GCKR rs1260326-P446L polymorphism, were determined in a cross-sectional analysis of 379 subjects with MetS participating in the LIPGENE dietary cohort. RESULTS: Among subjects with n-3 PUFA levels below the population median, carriers of the common C/C genotype had higher plasma concentrations of fasting insulin (P = 0.019), C-peptide (P = 0.004), HOMA-IR (P = 0.008) and CRP (P = 0.032) as compared with subjects carrying the minor T-allele (Leu446). In contrast, homozygous C/C carriers with n-3 PUFA levels above the median showed lower plasma concentrations of fasting insulin, peptide C, HOMA-IR and CRP, as compared with individuals with the T-allele. CONCLUSIONS: We have demonstrated a significant interaction between the GCKR rs1260326-P446L polymorphism and plasma n-3 PUFA levels modulating insulin resistance and inflammatory markers in MetS subjects. Further studies are needed to confirm this gene-diet interaction in the general population and whether targeted dietary recommendations can prevent MetS in genetically susceptible individuals. TRIAL REGISTRATION: ClinicalTrials.gov NCT00429195.

The effect of the plasma n-3/n-6 polyunsaturated fatty acid ratio on the dietary LDL phenotype transformation - insights from the LIPGENE study.

BACKGROUND & AIMS: LDL phenotype B is associated with obesity, insulin resistance, hypertriglyceridemia and oxidative stress. The effect of plasma n-3/n-6 PUFA ratio on LDL phenotype transformation was investigated. METHODS: Patients with metabolic syndrome (n=99) received one of four isocaloric diets: (A) High-fat (38% energy) SFA-rich diet (HSFA); (B) High-fat (38% energy), MUFA-rich diet (HMUFA); (C), low-fat (LF) (28% energy), high-complex carbohydrate diet with 1.24g/d oleic sunflower oil (LFHCC) and (D): low-fat (28% energy), high-complex carbohydrate diet, with 1.24g/d LC n-3 PUFA (LFHCC n-3) for 12 weeks. Analysis of plasma lipid profile and LDL phenotype was done pre- and post-interventions. RESULTS: Post-dietary change of LDL density was a main effect observed in all groups. LFHCC n-3 and HFMUFA diets resulted in favorable alteration of LDL phenotype from B to A and decreased LDL density. In contrast, increased LDL density was observed in HSFA and LFHCC groups. The plasma pre-n3/n6 PUFA, Apo E change and pre-Apo CIII/CII ratios explained in 65% the post-dietary change of LDL density in diet LFHCC n-3 consumers. CONCLUSIONS: Study demonstrates efficacy of dietary n-3 PUFA to modify pro-atherogenic to less atherogenic LDL phenotype in patients with metabolic syndrome. Study identifier at ClinicalTrials.gov was NCT00429195.