Alginates, traditionally used as thickeners, emulsifiers and stabilisers in food processing to make everything from ice cream to onion rings, have been found to have bioactive properties too. They act by restricting fat digestion and absorption into the body. This could enable them to be used in products to help people to "feel fuller" after eating them.
According to Jeffrey Pearson, professor of molecular physiology at the university of Newcastle, speaking at a recent Leatherhead Food Research food innovation day, certain alginates (but not all) act as potent inhibitors of pancreatic lipase and therefore have "great potential" to be used as an intervention in weight management and obesity. Lipase is an enzyme, which helps break down fat molecules in the human digestive system.
His team at Newcastle used a model gut system to investigate digestion in the mouth, stomach and small intestine. They demonstrated that alginate is released from bread used as a delivery system in the intestinal phase where lipase is most active. Greggs the bakery produced the bread, which contained 4% by weight of alginates, used by Pearson's researchers in subsequent human trials.
Promisingly, the human studies also demonstrated that alginates had no adverse effects on people, notably bowel "leakage", which has been a problem with other weight management products. The only negative effects were an increased thirst when a lot of alginate bread was consumed and a temporary increase in flatulence in the first week of consumption.
Pearson suggested that this research could lead to the development of foods that helped consumers achieve "health by stealth". "Nobody wants to eat healthy diets unless they are forced to," remarked Pearson.
"A lot of people felt fuller when they had alginate bread for food in the morning," he reported. The alginate bread is similar in appearance to ordinary bread, he said. "In all trials, people preferred alginate bread to ordinary bread since it had a good mouthfeel, better moisture and is easier to chew," he added. It also improves bread shelf-life.
If commercially successful products were to be developed, it might change the views about eating bread held by some sections of the population. "Women see bread as the devil in disguise when trying to lose weight," said Pearson.
However, as successful products emerge, there are commercial issues that remain to be resolved. "The big problem is the cost, because alginate is not cheap," said Pearson.