Dietary fibre from edible seaweeds: Chemical structure, physicochemical properties and effects on cholesterol metabolism

Abstract This brief review outlines the chemical structure, physicochemical properties and effects of seaweed polysaccharides on serum cholesterol levels. Some seaweed polysaccharides are used by the food industry as texture modifiers because of their high viscosity and gelling properties. In Asia, seaweeds have been used for centuries in salads, soups and as low-calorie dietetic foods. The dietary fibre which constitutes 25–75% of the dry weight of marine algae and represents their major component, is primarily soluble fibre. Nowadays, dietary fibre from different sources is known to decrease the risk of coronary heart disease, mainly due to its characteristics of dispersibility in water (water-holding capacity), viscosity, binding ability, absorptive capacity, faecal bulking capacity and fermentability in the alimentary canal. Indigestible viscous seaweed polysaccharides such as alginates, carrageenans and funorans, which are capable of forming ionic colloids, have shown positive effects on serum lipid levels in rats. The capacity of seaweed polysaccharides to lower serum cholesterol levels seems to be due to their ability to disperse in water, retain cholesterol and related physiologically active compounds and inhibit lipid absorption in the gastrointestinal tract.