Swine consuming 15 g of the resistant starch product per day over the course of 30 days were 54% less resistant to insulin than placebo-fed controls, reported researchers from the University at Buffalo (USA), King’s College London (UK), and the University of Manitoba (Canada).
The pigs consuming the resistant starch (RS) also experienced a 28% increase in total HDL cholesterol particles, compared to placebo, according to findings published in the Journal of Dietary Supplements.
“Data from this study suggest that in addition to the more well-characterized effect of RS intake in lowering blood glucose and improving insulin sensitivity, the consumption of RS may be beneficial in lipid management strategies by enhancing HDL particle number,” wrote the researchers, led by Dr Todd Rideout.
The researchers fed 12 Yorkshire pigs a synthetic Western diet (where fat accounts for 32.5% of calories compared to 11% in a standard diet) and randomly divided them into two groups: A placebo group; or 10 grams per day of RS per day. Swine are considered an excellent model for studying the human gut.
After 30 days, results showed that, compared to placebo, total HDL particles were 28 % higher in the RS group. In addition, fasting serum glucose was significantly lower, while insulin resistance, measured using the homeostatic model assessment (HOMA-IR), was improved without a change in insulin.
The researchers also reported a 141% increase in levels of the hormone GLP-1 (glucagon-like-peptide 1) following RS supplementation, compared to placebo. GLP-1 has several known functions, including appetite suppression and improved utilization of endogenous insulin, and is produced by cells in the intestine in response to fermentation.
“RS is indeed a highly fermentable substrate for colonic microbes, and we have previously characterized the fermentation of different varieties of RS in pigs compared with more well-characterized soluble (guar gum) and insoluble (cellulose) fibers,” they wrote. “Therefore, it is likely that the glucose-lowering effects of RS may be associated with selective stimulation of the microbiome, a scenario that has received recent research attention.”
The researchers concluded: “Additional studies should be pursued to further investigate the impact of RS supplementation on lipoprotein distribution in humans and to determine whether the observed increase in HDL particles number is paralleled by an increase in reverse cholesterol transport.”
Derek McLaren, VP of MSPrebiotics Inc., said that while he appreciates the value of pre-clinical animal model research, he is particularly excited about the soon-to-be-published human clinical data. “We’re very excited by the results and we can’t wait to share them with the public!”
Source: Journal of Dietary Supplements
Volume 14, Issue 3, Pages 334-345, doi: 10.1080/19390211.2016.1229371
“Dietary Resistant Starch Supplementation Increases High-Density Lipoprotein Particle Number in Pigs Fed a Western Diet”
Authors: T.C. Rideout et al.