Twelve weeks of supplementation with Ingredion’s Hi-Maize 260 type 2 resistant starch (RS2) were associated with significant reductions in levels of tumor necrosis factor-alpha (TNF-alpha), a marker of inflammation, but no changes were observed in other inflammatory markers, such as high-sensitivity C-reactive protein [hs-CRP], interleukin-6.
Data published in the American Journal of Clinical Nutrition indicated that the resistant starch was also associated with average decreases in heart rate of five beats per minute.
However, scientists from the University of Alabama at Birmingham, Louisiana State University, and the University of California-Davis found that the resistant starch did not lead to improvements in glycemic control, cardiovascular disease risk factors, ectopic fat, or energy metabolism.
“We report that RS2 supplementation does not improve cardiometabolic health in adults with prediabetes, although it does reduce TNF-alpha concentrations,” they wrote. “This lends support to newer evidence that high doses of fermentable carbohydrate supplementation may not always improve cardiometabolic health as so often claimed.
“Future studies are needed to determine whether there are potential subgroups of individuals—based on their baseline gut microbiota, diet composition, and other biological and environmental factors—who respond better to RS2 supplementation than others.
“This could lead to a better understanding of the potential beneficial effects of RS supplementation on metabolic health and whether such effects are modulated by diet composition or existing microbial populations in the gut.”
Starches can be divided into three groups: rapidly digestible starch (RDS, digested within 20 minutes), slowly digestible starch (SDS, digested between 20 and 120 minutes), and resistant starch (RS). The latter is not digested but is fermented in the large intestine and has 'prebiotic' properties.
Resistant starch can be found naturally in cold cooked potatoes, pasta and rice as well as baked beans and lentils.
The new study included 68 overweight adults with prediabetes, aged between 35 and 75. The participants were randomly assigned to receive daily supplements of RS2 (45 grams per day) or an equivalent amount of rapidly digestible starch amylopectin for 12 weeks.
Results showed that, compared to the control group, TNF-alpha levels decreased by an average of 2.1 picograms per mL, while heart rate also improved, but no significant differences between the groups were reported for insulin secretion, insulin sensitivity, blood pressure, cholesterol levels, or other markers of inflammation.
“Overall, we conclude that although RS2 may improve some inflammatory markers, it does not improve carbohydrate metabolism, ectopic fat, or cardiovascular disease risk factors in adults with prediabetes,” wrote the researchers.
Source: The American Journal of Clinical Nutrition
Published online ahead of print, doi: 10.1093/ajcn/nqy121
“Effect of 12 wk of resistant starch supplementation on cardiometabolic risk factors in adults with prediabetes: a randomized controlled trial”
Authors: C.M. Peterson et al.