n-3 Polyunsaturated Fatty Acids Increase: Thermic Effect of Food in Men with Metabolic Syndrome

PURPOSE: Effects on energy metabolism of a test meal and a two-week dietary intervention were observed in men with metabolic syndrome (MetS). Both the meal and the intervention included foods containing fish-derived n-3 polyunsaturated fats (PUFA). METHODS: Six men with MetS (46.7 ± 12.1 years, 37.2 ± 5.6 kg/m(2), mean ± standard deviation) completed two test days, separated by a 14-day dietary intervention during which they consumed at least 2.0 g per day of n-3 PUFA from supplied foods. Pre- and post-intervention measurements included body composition, resting metabolic rate (RMR), and the thermic effect of food (TEF) measured for six hours after ingestion of a test meal consisting of 1.43 g of fish-derived n-3 PUFA. RESULTS: Intakes of n-3 PUFA increased over the 14-day intervention, from 0.43 g per day ± 0.48 to 2.92 g per day ± 1.97 (p=0.013), while no changes were observed in total energy intakes, weight, body composition, or RMR (all p>0.05). The TEF increased by 51.3% (p=0.036), and the non-protein respiratory quotient decreased by 36.0% (p=0.700). CONCLUSIONS: Subjects increased their intake of fish-derived n-3 PUFA in an isocaloric manner while maintaining body weight and composition, and increased the TEF. More studies with larger sample sizes and longer intervention periods are required to confirm the use of fish-derived n-3 PUFA as a therapeutic dietary strategy for people with MetS.