A randomised crossover placebo-controlled trial investigating the effect of brown seaweed (Ascophyllum nodosum and Fucus vesiculosus) on postchallenge plasma glucose and insulin levels in men and women

Appl Physiol Nutr Metab. 2011 Dec;36(6):913-9. doi: 10.1139/h11-115. Epub 2011 Nov 16.


This study examined the impact of brown seaweed on post-load plasma glucose and insulin concentrations in men and women. Twenty-three participants (11 men, 12 women) aged 19-59 years were recruited in this double-blind, randomized, placebo-controlled crossover study. The test product consisted of a commercially available blend of brown seaweed (Ascophyllum nodosum and Fucus vesiculosus) with known inhibitory action on α-amylase and α-glucosidase activities (InSea²). Two 250 mg seaweed capsules and 2 placebo capsules were consumed on each occasion 30 min prior to the consumption of 50 g of carbohydrates from bread. Plasma glucose and insulin concentrations were measured over a period of 3 h postcarbohydrate ingestion at predetermined time points. Both treatments were separated by a 1-week washout period. Data were analysed using mixed models for repeated measures. Compared with placebo, consumption of seaweed was associated with a 12.1% reduction in the insulin incremental area under the curve (p = 0.04, adjusted for baseline) and a 7.9% increase in the Cederholm index of insulin sensitivity (p < 0.05). The single ingestion of 500 mg of brown seaweed had no significant effect on the glucose response (p = 0.24, adjusted for baseline). Glucose and insulin responses were similar between men and women. Consumption of the seaweed capsules was not associated with any adverse event. These data suggest that brown seaweed may alter the insulin homeostasis in response to carbohydrate ingestion.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Ascophyllum / chemistry*
  • Cross-Over Studies
  • Dietary Carbohydrates / metabolism
  • Double-Blind Method
  • Enzyme Inhibitors / adverse effects
  • Enzyme Inhibitors / therapeutic use
  • Female
  • Fucus / chemistry*
  • Glycoside Hydrolase Inhibitors
  • Humans
  • Hyperglycemia / prevention & control*
  • Hyperinsulinism / prevention & control*
  • Hypoglycemic Agents / adverse effects
  • Hypoglycemic Agents / therapeutic use*
  • Male
  • Middle Aged
  • Phytotherapy / adverse effects
  • Plant Extracts / adverse effects
  • Plant Extracts / therapeutic use*
  • Postprandial Period
  • Seaweed / chemistry*
  • Young Adult
  • alpha-Amylases / antagonists & inhibitors


  • Dietary Carbohydrates
  • Enzyme Inhibitors
  • Glycoside Hydrolase Inhibitors
  • Hypoglycemic Agents
  • Plant Extracts
  • alpha-Amylases