How Alginate Reduces Hunger
''Alginate is a fiber extracted from seaweed," Wiseman tells WebMD. "It's used as a sort of gelling agent in pudding."
The alginate studied was in liquid form. Once it reaches the acidic environment of the stomach, she says, the release of calcium in the stomach makes it gel.
"You swallow a drink but get this solid gel formed in the stomach," she says.
The gel is thought to slow down the emptying of food from the stomach. It may also distend the stomach. It mimics the effect of eating solid food, she tells WebMD.
Alginate in Drinks: Feeling Full
The study results are promising, says Lona Sandon, RD, assistant professor of clinical nutrition at the University of Texas Southwestern Medical Center in Dallas.
She reviewed the study results for WebMD but was not involved in the research.
"Meal-replacement drinks can be a valuable tool for some people trying to lose weight," she tells WebMD. "They can help control portions and calories. However, one of the biggest problems is that people complain of hunger within a few hours. Liquids typically empty from the stomach very quickly. Adding the right type and amount of alginate as an ingredient appears to help keep people feeling full longer."
However, she says, some other research finds that chewing is important for feeling satisfied. "Most people don't feel satisfied on liquid meal replacements," she says. "They tend to be more effective when in bar form."
The 30% hunger reduction found in the new study is probably enough to be noticeable, says Sandon, a spokeswoman for the American Dietetic Association. It might make the difference between feeling hungry an hour before your typical lunchtime or getting through to lunchtime without feeling very hungry, she says.