The results, published in the Journal of Nutritional Biochemistry, also showed that the acorn and sago prebiotics improved gut integrity, reducing so-called ‘leaky gut’ and inflammation.
The scientists reported an increase in hypothalamic signals in the brain, which is known to be important in regulating of metabolism in the body. This result indicated a potential role of the gut-brain axis.
“Our study discovered non-digestible fibers/prebiotics after extensive screening process from acorn and sago,” Hariom Yadav, PhD, Group Leader, Gut Microbiome and Metabolic Diseases at Wake Forest Medical Center in North Carolina and corresponding author on the study, told NutraIngredients-USA.
“Interestingly, these fibers are very efficiently fermentable by both human and mice gut microbiota, and increases the beneficial bacteria and produce beneficial metabolites like short chain fatty acids. Decreased short chain fatty acids are common in several human diseases like diabetes, obesity, aging, cancer and autoimmune diseases. Hence increasing the production of short-chain fatty acids by using our prebiotics can benefit these health ailments.”
Dr Yadav continued: “We also found that feeding of these prebiotics to obese/diabetic mice decreased leaky gut and inflammation. Leaky gut condition and inflammation are root cause of several human diseases including, obesity, diabetes and aging.
“Interestingly, several of these benefits were better in our acorn and sago prebiotics when we compared to a very well standard prebiotics called inulin.”
Glenn Gibson, Professor of Food Microbiology and head of Food Microbial Sciences at the University of Reading in the UK, and a pioneer and world-renowned expert in prebiotics, described the study as “interesting”.
Commenting independently, Prof Gibson told NutraIngredients-USA: “This study shows the potential health application of prebiotics in terms of markers of Metabolic Syndrome and its associated risk. The use of prebiotics from natural sources is relevant but needs confirmation in human studies. The same applies to the health aspects investigated here where mice were the model used.
“Having said that, in vitro studios with human feces seem to confirm the prebiotic effect - indicating that in vivo trials may also be positive in this regard.”
Prebiotics are defined as “a substrate that is selectively utilized by host microorganisms conferring a health benefit” (ISAPP, published in Nature Reviews Gastroenterology & Hepatology, 2017, Vol 14, pp. 491–502)
Dr Yadav and his co-workers isolated water soluble, non-digestible polysaccharides from acorn, quinoa, sunflower, pumpkin and sago seeds, and tested them in both in vitro by fermentation with the microorganisms in human feces and in vivo with lab mice.
The in vitro tests showed that the polysaccharides from acorns and sago were the more interesting to advance to the mouse studies. This was based on the observation that both acorns and sago extracts increased the abundance of Bacteriodetes and decreased the abundance of Firmicutes in fecal samples taken from heart failure patients.
Moving on to study acorn and sago polysaccharides in mice consuming a high-fat diet (a model for the Western diet in humans). The effects were compared with an established prebiotic, inulin.
The data from the mouse study showed that all three prebiotic treatments ameliorated the detrimental effects associated with a high-fat on glucose intolerance and insulin resistance. Interestingly, the novel prebiotics from acorns and sago were “comparatively superior to those seen in inulin-fed mice”.
All three prebiotics led to increases in levels of short chain fatty acids (SCFAs) in the murine guts.
Additional analysis showed that gut permeability and inflammatory markers in the mucosal layer of the intestine were “significantly reduced upon prebiotics feeding in [high fat diet]-fed mice”.
Prebiotic administration was also found to be linked to increases in hypothalamic energy signaling.
“[W]e demonstrate a new set of prebiotics from novel sources that could be exploited to ameliorate obesity and type 2 diabetes via modulating gut-microbiome-brain axis,” wrote Dr Yadav and his co-workers.
“Although these exciting results established that selected prebiotics are fermentable by human-gut microbiome and produce beneficial SCFAs using ex-vivo human fecal culture system, however, such effects might be different when directly fed to humans, hence further clinical studies are warranted to determine the such effects.”
Source: Journal of Nutritional Biochemistry
Published online ahead of print, doi: 10.1016/j.jnutbio.2019.01.011
“Prebiotics from acorn and sago prevent high-fat diet-induced insulin resistance via microbiome-gut-brain axis modulation”
Authors: S. Ahmadi et al.