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

Urszula Razny; Beata Kiec-Wilk; Anna Polus; Joanna Goralska; Malgorzata Malczewska-Malec; Dominika Wnek; Anna Zdzienicka; Anna Gruca; Caroline E Childs; Maria Kapusta; Krystyna Slowinska-Solnica; Philip C Calder; Aldona Dembinska-Kiec

doi:10.1016/j.bbacli.2015.05.001

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

BBA Clin. 2015 May 22:4:7-13. doi: 10.1016/j.bbacli.2015.05.001. eCollection 2015 Dec.

Affiliations

¹ Department of Clinical Biochemistry, Jagiellonian University Medical College, 31-501 Krakow, Poland.
² Department of Metabolic Diseases, Jagiellonian University Medical College, 31-501 Krakow, Poland.
³ Human Development and Health Academic Unit, Faculty of Medicine, University of Southampton, Tremona Road, SO16 6YD Southampton, United Kingdom.
⁴ Human Development and Health Academic Unit, Faculty of Medicine, University of Southampton, Tremona Road, SO16 6YD Southampton, United Kingdom; NIHR Southampton Biomedical Research Centre, University Hospital Southampton NHS Foundation Trust and University of Southampton, Tremona Road, SO16 6YD Southampton, United Kingdom.

Abstract

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/m(2)) 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.

Keywords: AUC, area under curve; BMI, body mass index; Caloric restriction; DHA, docosahexaenoic acid; Docosahexaenoic acid; EPA, eicosapentaenoic acid; Eicosapentaenoic acid; GIP, glucose dependent insulinotropic polypeptide; IGI, insulinogenic index; Insulin resistance; NEFA, non esterified fatty acids; OGIS, oral glucose insulin sensitivity index; OGTT, oral glucose tolerance test; Obesity; PC, phosphatidylcholine; PUFA, polyunsaturated fatty acids; n-3 polyunsaturated fatty acids.