South Dakota State
University
The secret ingredient
is in the flour, but its impact lies within the gut.
Adding resistant
starch to the diets of people with metabolic syndrome can improve bacteria in
the gut, according to research from South Dakota State University.
These changes help lower bad cholesterol and decrease inflammation associated with obesity.
These changes help lower bad cholesterol and decrease inflammation associated with obesity.
The American Heart
Association estimates that 34 percent of Americans have metabolic syndrome, a
combination of conditions which significantly increases their risk of
developing heart disease and Type 2 diabetes.
This is the first
study to examine the prebiotic impact of resistant starch type 4 known as RS4
-- a nondigestible, chemically modified wheat fiber -- in individuals with
metabolic syndrome, explained associate professor Moul Dey of the Department of
Health and Nutritional Sciences.
Unlike regular starch,
RS4 works as a functional fiber, Dey explained. Because it is not broken down
in the upper gastrointestinal tract, RS4 is fermented by the gut bacteria in
the colon. This produces new substances, such as short-chain fatty acids, that
have functions related to health.
"Human bodies harbor more bacterial cells than their own and therefore what we eat is not just for us but also for our bacteria," Dey said. "How well we feed them contributes to how well they take care of our health. That's where RS4 can help."
The results were
published in today's Scientific Reports, a Nature Publishing Group
academic journal.
The research was supported by MGP Ingredients, the National
Institutes of Health and the U.S. Department of Agriculture funding through the
South Dakota Agricultural Experiment Station. Funding agencies had no role in
the study design or outcome.
Using ingredient in
real food
The study focused on
12 women and 8 men with metabolic syndrome from 2 Hutterite colonies in eastern
South Dakota. These individuals had abdominal obesity accompanied by two of
four other conditions -- high blood pressure, high blood sugar levels or
diabetes, high level of triglycerides in the blood stream and low levels of
good cholesterol. Twelve participants were on medications for one or more of
these conditions.
The starch was
incorporated into the intervention group's flour. All the meals in this
communal setting are prepared from scratch and every meal contains one or two
flour-based items.
"As the study was
blinded, they didn't even realize they were doing anything different, yet they
were improving their health," Dey said. "Our hypothesis was that
adding RS4 in the diet makes bacteria happy and increases the health benefit of
the food people normally eat. The beauty of this study is that it showed this
is possible in a real-life setting."
Unlike most dietary
intervention studies, the researchers used a free-living community style
environment and made minimal modifications to the participants' habitual diet.
A healthy diet and
lifestyle can reduce the risks associated with metabolic syndrome. But,
altering lifelong habits and adhering to dietary guidelines in the long run is
difficult. "This is where stealth ingredients, like RS4, make a lot of
sense," Dey pointed out. However, she added, "making healthy
lifestyle choices remains critical."
The intervention was
conducted in two 12-week sessions with a two-week hiatus. This allowed
researchers to switch the intervention and control groups so that each group
served as its own control. Stool and blood samples were collected and a DXA
scan to evaluate body composition was done before and after the intervention.
Doctoral candidate
Bijaya Upadhyaya, master's student Robert Juenemann and postdoctoral researcher
Sailendra Nichenametla worked on the research. This work also involved
collaboration with U.S. Food and Drug Administration scientist Ali Reza
Fardin-Kia. Other SDSU collaborators were assistant professor Lacey McCormack,
professor Jeffrey Clapper of animal science and professor Bonnie Specker,
director of the E.A. Martin Endowed Program in Human Nutrition.
Decreasing
cholesterol, improving gut bacteria
Use of resistant
starch decreased all types of cholesterols. The participants' baseline
cholesterol levels were not high, in part, because of the medications they were
taking. Despite that, the average total cholesterol of the participants dropped
significantly after the intervention. In addition, the researchers observed a
small decrease in average waist circumference and body fat percentage.
DNA analysis of stool
samples using next-generation sequencing showed a change in the gut bacterial
community structure after the intervention. "Essentially, consuming RS4
improved the balance of bacteria in the gut, some of which correlated with
improved indicators of metabolic health as well as with increased levels of
short chain fatty acids."
Currently, RS4 is only
available to food manufacturers for use as a fiber ingredient. Dey hopes that
one day consumers will be able to buy flour fortified with RS4.