Researchers from Unilever's Research and Development in the Netherlands compared the effects on hunger after drinking a meal-replacement drink with the fiber, alginate, at two different strengths and without it.
The higher concentration alginate drink reduced hunger longest -- up to nearly five hours after drinking it.
"We didn't measure calorie intake, but you would anticipate that would be translated to a relevant reduction in calorie intake," says study co-researcher Sheila Wiseman, PhD.
She cannot estimate when the new drink will be on the market. The researchers are still working out what she calls ''technical challenges" with the technology. One is to improve the ''slimy mouth feel" that can accompany a drink with a high concentration of the alginate, she tells WebMD.
Alginate is already added to some other meal replacements on the market.
The study is published in the journal Obesity.
Reducing Hunger With Alginate
Wiseman and her colleagues asked 23 volunteers to drink three different drinks on three occasions:
- A chocolate meal-replacement drink under development by Slim-Fast, a Unilever brand.
- A chocolate meal-replacement drink with 0.6% alginate.
- A chocolate meal-replacement drink with 0.8% alginate.
Each drink had about 190 calories, nearly 7 grams of fat, 10 grams of protein, and about 24 grams of carbohydrates. All had similar amounts of fiber, from 4.7 to 5.2 grams a serving.
Participants were ages 18 to 60. Their body mass indexes (BMIs) ranged from healthy to obese.
They drank one of the three drinks for breakfast. Every half-hour from the time they drank at 8 a.m. until 1 p.m. the participants rated their hunger and fullness.
The higher-concentrate alginate drink worked best to delay hunger and keep drinkers feeling full. At the five-hour mark, for instance, those who drank the comparison drink rated their fullness at 10 on scale of zero to 80. Those who drank the high-alginate drink rated it at over 20.
On the hunger rating, those who drank the higher alginate staved off hunger for at least four hours, longer than the other drinks. On a hunger scale of zero to 80, those who had the high alginate drink rated their hunger, on average, at about 68 before drinking the beverage and about 63 at 4.5 hours later. By five hours, their hunger was back to what it was before drinking it.
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.