Fish oil supplemented for 9 months does not improve glycaemic control or insulin sensitivity in subjects with impaired glucose regulation: a parallel randomised controlled trial

Louise F Clark, M C Thivierge, Claire A Kidd, Susan C McGeoch, Prakash Abraham, Donald W M Pearson, Graham Horgan, Grietje Holtrop, Frank Thies, Gerald E Lobley

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

The effects of fish oil (FO) supplementation on glycaemic control are unclear, and positive effects may occur only when the phospholipid content of tissue membranes exceeds 14% as n-3 PUFA. Subjects (n 36, thirty-three completed) were paired based on metabolic parameters and allocated into a parallel double-blind randomised trial with one of each pair offered daily either 6 g of FO (3·9 g n-3 PUFA) or 6 g of maize oil (MO) for 9 months. Hyperinsulinaemic-euglycaemic-euaminoacidaemic (HIEGEAA) clamps (with [6,6 2H2 glucose]) were performed at the start and end of the intervention. Endogenous glucose production (EGP) and whole-body protein turnover (WBPT) were each measured after an overnight fast. The primary outcome involved the effect of oil type on insulin sensitivity related to glycaemic control. The secondary outcome involved the effect of oil type on WBPT. Subjects on FO (n 16) had increased erythrocyte n-3 PUFA concentrations >14%, whereas subjects on MO (n 17) had unaltered n-3 PUFA concentrations at 9%. Type of oil had no effect on fasting EGP, insulin sensitivity or total glucose disposal during the HIEGEAA clamp. In contrast, under insulin-stimulated conditions, total protein disposal (P=0·007) and endogenous WBPT (P=0·001) were both increased with FO. In an associated pilot study (n 4, three completed), although n-3 PUFA in erythrocyte membranes increased to >14% with the FO supplement, the enrichment in muscle membranes remained lower (8%; P<0·001). In conclusion, long-term supplementation with FO, at amounts near the safety limits set by regulatory authorities in Europe and the USA, did not alter glycaemic control but did have an impact on WBPT.

Original languageEnglish
Pages (from-to)75-86
Number of pages12
JournalBritish Journal of Nutrition
Volume115
Issue number1
Early online date5 Nov 2015
DOIs
Publication statusPublished - 14 Jan 2016

Keywords

  • Aged
  • Blood Glucose
  • Dietary Fats, Unsaturated
  • Dietary Supplements
  • Double-Blind Method
  • Erythrocytes
  • Fasting
  • Fatty Acids, Omega-3
  • Female
  • Fish Oils
  • Gluconeogenesis
  • Glucose Clamp Technique
  • Humans
  • Insulin
  • Insulin Resistance
  • Male
  • Middle Aged
  • Proteins
  • Journal Article
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

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