Carbohydrates take many forms—but lately, certain ones are getting more attention: the kinds of carbs that resist digestion in the upper portion of the gastrointestinal tract and continue on to meet the gut microorganisms in the colon. Dr. Laure Bindels, Professor at Université Catholique de Louvain (Belgium), is wondering whether the health benefits of these complex carbohydrates, including resistant starch and prebiotics, can be used to help treat obesity and metabolic syndrome—and if so, the mechanisms by which they might act.
“You can improve insulin sensitivity in healthy people [with resistant starch],” says Bindels in an interview with GMFH editors. She goes on to cite trials showing that, in addition, when people with metabolic syndrome consume resistant starch, they have an easier time keeping their blood glucose levels within the normal range.
The reason resistant starch can keep blood sugar stable after a meal is because it’s less readily digestible than other starches. Resistant starch is made up of glucose molecules, which are attached to each other to form long chains. When it enters the digestive tract, it resists being broken apart into its individual glucose molecules—in part, because it contains a relatively high percentage of something called amylose. The glucose chains in amylose are wound into a tight coil, so digestive enzymes have difficulty loosening the bonds that hold them together.
But so far, Bindels notes, it’s not yet fully understood whether resistant starch can actually help people lose weight. “In obese rodents, resistant starch can improve, generally speaking, insulin sensitivity and fat mass. But in humans, I’m not aware of a study that showed that fat mass is actually improved,” explains Bindels. She says this might be because of a difference in mechanism—so the way in which resistant starch affects insulin’s control of blood sugar could involve a totally different process in the body from the way it affects weight.
Bindels continues, “Trying to understand the mechanisms of this is what has driven my scientific work for a few years now. Clearly there are several mechanisms by which resistant starch works.”
She goes on, “We found out that in rodents resistant starches can improve insulin sensitivity independently of the gut microbiota, possibly through a modulation of the bile acids,” she says. “But other beneficial effects of resistant starches may rely on their ability to modulate the gut microbiota.”
So while resistant starch isn’t a sure-fire way to lose weight for those with obesity or metabolic syndrome, it can have some positive effects on blood sugar and on the gut microbiota. Moreover, it’s easy to consume in foods like green bananas, peas, and cooked legumes—and even in foods like rice and potatoes that have been cooked and then cooled.
In her investigations into the ability of specific food components to change the manifestation of disease, Bindels is also looking at how dietary components can affect cancer-related cachexia—a condition of weakness, involving muscle wasting or weight loss.
“I’m a pharmacist by training, but as a pharmacist I don’t encourage people to take drugs if it is not absolutely necessary,” she says. “I’m convinced we can use food to change our gut’s microbial metabolism, and then have an impact on disease.”
Bindels LB, Neyrinck AM, Claus SP, et al. Synbiotic approach restores intestinal homeostasis and prolongs survival in leukaemic mice with cachexia. The ISME Journal. 2016; 10: 1456–1470.
Bindels LB, Seguar Munoz RR, Gomes-Neto JC, et al. Resistant starch can improve insulin sensitivity independently of the gut microbiota. Microbiome. 2017; 5:12.
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