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ORIGINAL RESEARCH COMMUNICATION |
1 From the Department of Physiology, University of Murcia, Murcia, Spain (MG); the Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging, Tufts University School of Medicine, Boston, MA (MG, Y-CL, JS, LDP, C-QL, and JMO); the Department of Epidemiology, University of Alabama at Birmingham, Birmingham, AL (DKA); and the Department of Experimental and Clinical Pharmacology, University of Minnesota, Minneapolis, MN (MYT).
2 Supported by the Seneca Foundation from the Government of Murcia (project 02934/PI/05 to MG); the Government of Education, Science and Research of Murcia (project BIO/FFA 07/01-0004 to MG); The Spanish Government of Science and Innovation (projects AGL2008-01655/ALI to MG); and NIH (1R21AR055228-01A1, U01 HL72524, HL54776, and DK075030) and the US Department of Agriculture Research Service (53-K06-5-10 and 58–1950-9-001) to JMO and DKA. 3 Address correspondence to M Garaulet, Department of Physiology, Faculty of Biology, University of Murcia, Campus de Espinardo, s/n 30100, Murcia, Spain. E-mail: garaulet{at}um.es.
Background: Disruption of the circadian system may be causal for manifestations of the metabolic syndrome (MetS).
Objective: The objective was to study the associations of 5 CLOCK polymorphisms with MetS features by analyzing fatty acid (FA) composition from dietary and red blood cell (RBC) membrane sources.
Design: Participants (n = 1100) in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) study were included. Dietary intake was estimated with a validated questionnaire. Anthropometric and biochemical measurements and genotypes were determined. Postprandial lipids and the FA composition of RBC membranes were analyzed.
Results: CLOCK single nucleotide polymorphisms were significantly associated with obesity and individual components of MetS. For single nucleotide polymorphism rs4580704, minor allele carriers had a 46% lower risk of hypertension than did noncarriers. The monounsaturated fatty acid (MUFA) content of RBC membranes, particularly oleic acid, changed according to CLOCK genetic variants (P < 0.05). We identified significant gene-diet interactions associated with MetS at the CLOCK locus. By dichotomizing MUFA intake, we found different effects across rs4580704 genotypes for glucose (P = 0.020) and insulin resistance (P = 0.026). The protective effect of the minor allele on insulin sensitivity was only present when MUFA intake was >13.2% of energy. We also found different effects across CLOCK 3111T
C genotypes for saturated fatty acid intake (% of energy) (P = 0.017). The deleterious effect of gene variants on waist circumference was only found with high saturated fatty acid intakes (>11.8%).
Conclusions: CLOCK polymorphisms interact with FAs to modulate MetS traits. The dietary source and membrane content of MUFAs are implicated in the relations between alterations in the circadian system and MetS.