Food supplement appears to prevent weight gain

A newly developed food supplement appears to prevent weight gain and trim fat around the waist, researchers say.

However, the chemical compound doesn't seem to help people lose pounds, and the preliminary study is so small that the findings could be misleading.

Still, it did "lower appetite and prevented weight gain in overweight people," said study co-author Gary Frost, chair of nutrition and dietetics at Imperial College London. "This is the first time that a food ingredient has been shown to decrease weight gain."

The ingredient in question contains propionate, a fatty acid that's created when fiber ferments in the colon.

Propionate "does a number of things in the body," Frost said. "It is used for energy by the colon and liver. It can be used to make glucose in the liver." And, he said, it appears to affect how much people eat by boosting signals that suppress appetite.

Fiber is considered an aid to digestion and is thought to help people feel full. But that's not certain, Frost said.

"There are lots of short-term studies that show fiber suppresses appetite but no long-term studies. We think that this is because the amount of fiber needed to be consumed to affect appetite in the long term is two to three times the current recommendation," he explained.

In the new study, researchers developed a chemical compound that includes propionate and gave it in fruit juice to half of 20 volunteers. The others got only inulin, a plant fiber.

The volunteers then got to eat as much as they wanted from a buffet. Those who'd consumed the propionate ate 14 percent less on average than others, the researchers said.

Then the researchers followed 49 overweight adults, ages 40 to 65, as they received either a propionate supplement or inulin alone and completed a six-month study.

Of the 25 who took the supplement, just one gained more than 3 percent of body weight, compared to six of the 24 who took inulin. Those who took the supplement also had less fat around their waists.

What's going on? Frost said propionate might affect signals that suppress appetite, "but we are not sure which ones." It may also affect the metabolism of fat cells, he said.

According to Frost, there were no major side effects from taking the supplement.

The study was funded by the UK Biotechnology and Biological Sciences Research Council.

Rob Knight, a professor of chemistry and biochemistry at the University of Colorado, said the supplement had a "relatively small effect" in a small number of people. And it didn't seem to lead to weight loss, even when people took in fewer calories, added Knight, who wasn't involved in the study.

It's possible, he said, that the supplement "actually makes the gut bacteria more efficient at extracting nutrients from the diet." This would be undesirable because that would lead to more weight, he noted.

Another specialist in gut bacteria, professor Harry Flint of the University of Aberdeen in Scotland, praised the study as "carefully conducted and convincing, particularly since the effects are demonstrated in human volunteers." However, he cautioned against seeing the supplement as a "magic pill."

There's no way to buy this supplement now, but Frost said researchers are working with a food company to develop a product.

The study was published Dec. 10 in the journal Gut.

In another study, this one published recently in the journal Heart, researchers found that people with midriff bulge have an increased risk of cardiac arrest -- a sudden malfunction of the heart's electrical system. This is often fatal.

Dr. Selcuk Adabag, a cardiologist at Veterans Affairs Medical Center in Minneapolis, and colleagues found that middle-age adults with the highest waist-to-hip ratio had twice the risk of sudden cardiac death compared to people with a ratio in the normal range. Cardiac arrest is linked to 300,000 deaths in the United States each year, they said.