Effect of Hydrocolloids on Lowering Blood Glucose

There is growing interest in lowering the post-prandial blood glucose response (PPG) to carbohydrate-rich meals, to help reduce risks of chronic cardiometabolic diseases. Starch digestibility is mainly determined by the intrinsic starch characteristics such as amylose/amylopectin ratio and the botanical source. Processing factors such as cooking, baking and cooling also determine the glycaemic effects. Much effort has been dedicated to transforming rapidly digestible starch (RDS) into slowly digestible starch (SDS) by changing the properties of the starch, but this is complicated by the simultaneous formation of resistant starch (RS), which in large amounts can lead to gastrointestinal complaints. Hydrocolloids contain colloid particles, either digestible such as starch or indigestible such as gums (viscous/gelling fibres), dispersed in water. SDS content can be increased by adding hydrocolloids which are viscous (such as guar gum) or gel-forming (alginates, pectins) under gastrointestinal conditions, and these can lower PPG. Both the viscosifying and gelling potential of these hydrocolloids are related to their concentration and intrinsic properties e.g., the hydrodynamic properties, molecular weight, and solubility. In addition, the hydrodynamic properties of the gums depend on the solvent nature and environment i.e. food matrix and composition of gastrointestinal fluid and mechanical forces exerted by the body. Lastly, in vitro methods are an inexpensive tool to evaluate the properties of hydrocolloids under gastrointestinal conditions, to screen and prioritize hydrocolloid-containing materials for clinical testing of their PPG-lowering efficacy, and clarify their mechanism of action, which can be used to further optimise effects.