Effect of caloric restriction with or without n-3 polyunsaturated fatty acids on insulin sensitivity in obese subjects: A randomized placebo controlled trial

摘要

Background Caloric restriction and n-3 polyunsaturated fatty acid (PUFA) supplementation protect from some of the metabolic complications. The aim of this study was to assess the influence of a low calorie diet with or without n-3 {PUFA} supplementation on glucose dependent insulinotropic polypeptide (GIP) output and insulin sensitivity markers in obese subjects. Methods Obese, non-diabetic subjects (BMI 30–40 kg/m2) and aged 25–65 yr. were put on low calorie diet (1200–1500 kcal/day) supplemented with either 1.8 g/day n-3 {PUFA} (DHA/EPA, 5:1) (n = 24) or placebo capsules (n = 24) for three months in a randomized placebo controlled trial. Insulin resistance markers and {GIP} levels were analysed from samples obtained at fasting and during an oral glucose tolerance test (OGTT). Results Caloric restriction with n-3 {PUFA} led to a decrease of insulin resistance index (HOMA-IR) and a significant reduction of insulin output as well as decreased {GIP} secretion during the OGTT. These effects were not seen with caloric restriction alone. Changes in {GIP} output were inversely associated with changes in red blood cell {EPA} content whereas fasting {GIP} level positively correlated with HOMA-IR index. Blood triglyceride level was lowered by caloric restriction with a greater effect when n-3 {PUFA} were included and correlated positively with fasting {GIP} level. Conclusions Three months of caloric restriction with {DHA} + {EPA} supplementation exerts beneficial effects on insulin resistance, {GIP} and triglycerides. General significance Combining caloric restriction and n-3 {PUFA} improves insulin sensitivity, which may be related to a decrease of {GIP} levels.