News Release Distributed 01/27/14
BATON ROUGE, La. – Fiber is an essential part of any healthy diet, and it may be the key to success for people looking to lose weight. A fermentable fiber known as resistant starch, which is found in peas, beans, lentils and some grain products, could help lower body fat, according to Michael Keenan, an associate professor in the LSU AgCenter's School of Nutrition and Food Sciences.
Keenan said there are three speeds at which starches digest: fast, slow and resistant. While fast- and slow-digesting starches are broken down in the small intestine and release energy to the body, resistant starch resists being digested.
Keenan is studying how body fat is affected by consuming resistant starch, which is lower in energy and ferments in the large intestine. These two qualities could aid weight loss and have other health benefits, he said.
There are two ways resistant starch helps lower fat levels. First, resistant starch contains less energy than fast- and slow-digesting starches, which means fewer calories. The other benefit is fermentation — foods that resist digestion in the small intestine move to the large intestine, where they ferment.
During fermentation, fermentable fibers such as resistant starch feed bacteria that have been shown to be beneficial to human health, Keenan said. Fermentation produces more of these beneficial bacteria, which can affect body fat and glucose levels in a way that encourages weight loss. He said the bacteria can also affect hormones that influence energy balance and food intake because of fatty acids produced by fermentation.
Not everyone responds to resistant starch, however. Some rodents used in Keenan's study did not seem to produce enough bacteria as a result of eating resistant starch in corn to significantly affect their level of body fat.
In any case, it is important to consume a variety of types of fibers and meet the requirement for fiber, which ranges from 21 to 38 grams a day depending on age and sex, according to the Mayo Clinic. Keenan said people should eat fermentable and nonfermentable fiber because each type has its own benefits.
Keenan's work thus far has been with rodents in a lab setting and is supported by a $94,000 grant from Ingredion Inc., a food ingredients producer located in Illinois. Keenan is also participating in human resistant starch studies funded by a total of $1.6 million of grants in studies led by Eric Ravussin, a researcher at the Pennington Biomedical Research Center, and in collaboration Roy Martin, a scientist with the University of California at Davis.