Two specific kinds of dietary fiber could lead to weight loss if taken daily over a long term, according to a new study conducted at the University of Illinois College of Agricultural, Consumer and Environmental Sciences.

Despite research suggesting that certain dietary fibers can increase the presence of beneficial gut bacteria and reduce the risk of colon cancer, type 2 diabetes and other diseases, many people don't get the daily recommended amount.

The new study led to a novel finding, which involved a shift in the ratio of Bacteroidetes to Firmicutes, in which Bacteroidetes overtook the latter.

"This was of particular interest to us because other research has shown that having more Bacteroidetes may be beneficial because the higher that proportion is, the individual tends to be leaner.

With higher Firmicutes, that individual tends to be more obese," says Dr. Hannah Holscher, a U of I postdoctoral researcher and registered dietician in animal sciences.

In the current study, a team led by Dr. Kelly Swanson, a U of I professor of nutrition, built on his previous research, in which researchers had worked with 20 healthy male participants whose average fiber intake was 14 grams per day and given them snack bars.

The control group received fiberless snack bars and the two test groups ate either bars that contained 21 grams of polydextrose -- a common fiber food additive -- or bars with 21 grams of soluble corn fiber.

Using fecal samples from the aforementioned study, they conducted DNA sequencing to examine the spectrum of bacterial genetic information in the fecal microbiota.

In addition to the shift in the ratio of species, whole-genome sequencing data revealed shifts in the functional capacity of the microbiota associated with fiber intake.

For example, Dr. Holscher remarks on a decrease in genes associated with protein metabolism, which likely explains the reduced protein fermentation that occurred in the digestive tracks of participants who consumed fiber supplements.

"We don't know if there is any causality for weight loss, but studies have shown that having a higher fiber diet is protective against obesity. It's an exciting shift and helps to drive researchers to study these fibers as part of a weight loss diet."

Polydextrose and soluble corn fiber are typically found in packaged foods such as cereal, cereal bars and baking mixes.

According to Dr. Holscher, food production companies are interested in including them because they are lower in calories and do not deter from the taste or texture of their products.

The study was published in the American Journal of Clinical Nutrition.