Morales D., Shetty S.A., López-Plaza B., Gómez-Candela C., Smidt H., Marín F.R., Soler-Rivas C. Modulation of human intestinal microbiota in a clinical trial by consumption of a β-D-glucan-enriched extract obtained from Lentinula edodes. European Journal of Nutrition. 2021;60(6):3249–3265.
Rationale
Shiitake β-glucans reach the colon largely intact — a candidate prebiotic. This trial measured whether 8 weeks of a β-glucan extract shifts the microbiota, with lipid and inflammatory markers alongside.
Methods
A double-blind placebo-controlled parallel RCT: 52 participants with untreated moderate hypercholesterolemia consumed food products containing the shiitake β-D-glucan mix (10.4 g/day BGE, ≈3.5 g/day β-glucans) or placebo for 8 weeks. Lipids, inflammatory markers (IL-1β, IL-6, TNF-α, oxLDL) and fecal microbiota were profiled.
Results
Lipids and inflammatory markers did not change significantly. The colonic microbiota, however, shifted differently than under placebo — with individual genera correlating with cholesterol-metabolism markers. The intervention was safe and pushed participants' fiber intake to recommended levels.
Conclusions
A null on lipids/inflammation but a real microbiota modulation — shiitake β-glucans act on the gut ecosystem even where systemic markers stay flat.
Worth noting
The microbiota-vs-lipids dissociation is the lesson: measurable ecological effect, no clinical-marker effect in 8 weeks — the timescale or the dose may simply be wrong for lipid endpoints. n=52 moderate-hypercholesterolemia is a reasonable test population; honest nulls like this keep the catalog credible.