title: Effect of caloric restriction with or without n-3 polyunsaturated fatty acids on insulin sensitivity in obese subjects: A randomized placebo controlled trial.
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.
  
  
  CONCLUSIONS
  Combining caloric restriction and n-3 PUFA improves insulin sensitivity, which may be related to a decrease of GIP levels.
authors.affiliation: Department of Clinical Biochemistry, Jagiellonian University Medical College, 31-501 Krakow, Poland.
authors.forename: Urszula
authors.initials: U
authors.lastname: Razny
authors.affiliation: Department of Metabolic Diseases, Jagiellonian University Medical College, 31-501 Krakow, Poland.
authors.forename: Beata
authors.initials: B
authors.lastname: Kiec-Wilk
authors.affiliation: Department of Clinical Biochemistry, Jagiellonian University Medical College, 31-501 Krakow, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Polus
authors.affiliation: Department of Clinical Biochemistry, Jagiellonian University Medical College, 31-501 Krakow, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Goralska
authors.affiliation: Department of Clinical Biochemistry, Jagiellonian University Medical College, 31-501 Krakow, Poland.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Malczewska-Malec
authors.affiliation: Department of Clinical Biochemistry, Jagiellonian University Medical College, 31-501 Krakow, Poland.
authors.forename: Dominika
authors.initials: D
authors.lastname: Wnek
authors.affiliation: Department of Clinical Biochemistry, Jagiellonian University Medical College, 31-501 Krakow, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Zdzienicka
authors.affiliation: Department of Clinical Biochemistry, Jagiellonian University Medical College, 31-501 Krakow, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Gruca
authors.affiliation: Human Development and Health Academic Unit, Faculty of Medicine, University of Southampton, Tremona Road, SO16 6YD Southampton, United Kingdom.
authors.forename: Caroline E
authors.initials: CE
authors.lastname: Childs
authors.affiliation: Department of Clinical Biochemistry, Jagiellonian University Medical College, 31-501 Krakow, Poland.
authors.forename: Maria
authors.initials: M
authors.lastname: Kapusta
authors.affiliation: Department of Clinical Biochemistry, Jagiellonian University Medical College, 31-501 Krakow, Poland.
authors.forename: Krystyna
authors.initials: K
authors.lastname: Slowinska-Solnica
authors.affiliation: 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.
authors.forename: Philip C
authors.initials: PC
authors.lastname: Calder
authors.affiliation: Department of Clinical Biochemistry, Jagiellonian University Medical College, 31-501 Krakow, Poland.
authors.forename: Aldona
authors.initials: A
authors.lastname: Dembinska-Kiec
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