Over the last few years we’ve been fed hints that nutraceutical mushrooms may play a role in the composition of the gut microbiome. First there was an in vitro study. Then, in August 2014, a clinical trial from Harvard Medical School found that Turkey Tail (biomass) polysaccharides acted as prebiotics in the digestive tract.
Now, a recent study in Nature Communications found that Reishi (Ganoderma lucidum) reduced obesity in mice by affecting the composition of the gut microbiome. Now, I’m not one to jump at the sight of research ‘against obesity’ as if fat-shaming. But we already knew that Reishi impacts insulin sensitivity, but microbiome alteration is a new piece of data.
Here’s how the study worked. Mice were fed a high-fat diet and gained weight. The obese mice were then given a Reishi mycelial water extract. Markers of inflammation decreased, as did body weight and fat accumulation. There were also increased levels of Treg cells in the liver after Reishi water extract supplementation. The high molecular weight polysacchardies (>300kDa) are believed to be responsible for these effects. The microbiota composition improved–particularly with the Firmicutes-to-Bacteroidetes ratio, and with decreased levels of endotoxin-producing Proteobacteria. The same effects was observed in obese mice who received fecal transplants from the Reishi-treated mice. This means that the gut microbiome was directly affected by Reishi, enough to reproduce the same effects in mice with similar baseline conditions.
This is a fascinating development. We know mushrooms positively impact immunity, and immunity and digestive health are intrinsically linked. This study sheds light on a new dimension in which mushrooms may be affecting physiology–by supporting probiotic or beneficial microflora, tightening intestinal junctions, and reducing inflammatory markers. Furthermore, the fact that Treg cells were upregulated in the liver is exciting in itself.
The micrbiome is the new frontier of research, and I can’t wait to see what happens next.
References (all available as free full text)
Pallav K, Dowd SE, Villafuerte J, Yang X, Kabbani T, Hansen J, Dennis M, Leffler DA, Newburg DS, and Kelly CP. Effects of polysaccharopeptide from Trametes versicolor and amoxicillin on the gut microbiome of healthy volunteers: a randomized clinical trial. Gut Microbes. United States; 2014;5(4):458-67.
Chang CJ, Lin CS, Lu CC, Martel J, Ko YF, Ojcius DM, Tseng SF, Wu TR, Chen YY, Young JD, and Lai HC. Ganoderma lucidum reduces obesity in mice by modulating the composition of the gut microbiota. Nat Commun. England; 2015;6:7489.