The effect of seaweed enriched bread on carbohydrate digestion and the release of glucose from food

Matthew D. Wilcox,Moaz Zulali,Xing Yang,Paul Cherry,Chris J. Seal,Peter I. Chater,Edward J. Okello,Jeffrey P. Pearson

doi:10.1016/j.jff.2021.104747

Abstract

Two seaweeds; Ascophyllum nodosum and Fucus vesiculosus, were incorporated into bread at 0.5 and 2% and their effect on blood glucose in vivo and carbohydrate digestion in vitro were studied. In the five way randomised placebo controlled double blind pilot trial (n=10) each volunteer consumed 100g of available carbohydrate (from bread) and their blood glucose was measured over two hours. The breads were tested in a human digestion model and compared against control bread and control bread with the equivalent amount of seaweed. In the pilot human study the enriched breads did not cause any significant reductions in iAUC of blood glucose with average reductions of 0.1±44.4%, 8.2±19.3%, 1.0±54.3% and 2.7±31.9% for 0.5% F.vesiculosus, 0.5% A.nodosum, 2% F.vesiculosus, and 2% A.nodosum respectively. However, seaweed added alongside the control bread in vitro significantly reduced the level of carbohydrate digestion compared to the control bread. F.vesiculosus or A.nodosum can reduce carbohydrate digestion, however baking into bread reduces the effect.

Highlights

The seaweeds had a polyphenol content of 11.5 ± 4.7 mg gallic acid equivalents (GAE) /g of seaweed extracted in deionised water for Ascophyllum nodosum and 165.9 ± 59.3 mgGAE/g for Fucus vesiculosus
Polyphenol extracts of brown seaweeds have been shown to be effective against the activity of carbohydrate digesting enzymes (Roy et al, 2011; Nwosu et al, 2011; Murugan et al, 2015; Lordan, 2013; Xu et al, 2012), as well as in this study when unbaked seaweed has been tested in the model gut system (MGS), there is only limited in vivo data
All the seaweed enriched bread tested in human in this study did show a reduction in incremental area under the blood glucose curve, the reductions were not significantly different to the control bread

Summary

Introduction

Brown seaweeds are rich in polyphenols, typically between 0.1 and 1.5% (dry weight) (Schiener et al, 2015; Tabassum et al, 2016), but with Ascophyllum nodosum containing higher amounts (6% dry weight) (Parys et al, 2009; Connan, et al, 2004) and F. vesiculosus higher again (up to 20% dry weight) (Ovchinnikov et al, 2020). The major polyphenols found in brown seaweeds are phlorotannins, which are oligomers of phloroglucinol. One potential treatment to aid glycaemic control has used seaweeds and their polyphenols (Murugan et al, 2015), showing promising results in vitro (Lordan, 2013) and with Ecklonia kurome Okamura in genetically diabetic mice (Xu et al, 2012). Tar geting the action of glucosidases has been shown to be a useful method to help with glycaemic control (Kim et al, 2016)

Methods

Results

Conclusion