Mushrooms, gut microbiota and cancer: a scoping review with qualitative synthesis
By Kirsten Chick - Nutrition Science and Practice
Abstract
Background
Cancer is a leading cause of death worldwide. The use of mushrooms alongside conventional treatment is popular within integrative oncology, and in exploring their cancer-preventative action, attention has turned to the role of mushroom-driven changes to gut microbiota.
Aim
The aim of this paper is to map and synthesise the evidence that examines the impact of mushrooms on cancer-related immunological processes due to their potential interaction with the gut microbiota.
Methodology
PubMed, the Cochrane Library and the Allied and Complementary Medicine Database were searched using the primary search terms “Cancer”, “Microbiota” and “Mushrooms”. Relevant data were tabulated, and studies were critically appraised and qualitatively analysed.
Findings
139 studies were screened and 23 identified (20 murine, one in vitro, one in silico, and one cross-sectional). The most frequent mushroom and cancer studied were Ganoderma lucidum and colorectal cancer, respectively. 85% of murine studies found evidence of tumour reduction, and 12 studies found changes to cytokines. Twenty-two studies reported gut microbiota changes, eight of which found changes to diversity, two identified changes to the Firmicutes/Bacteroidetes ratio, and four found restored cancer-related pathways in gene pathway enrichment analysis. Six studies found increased short chain fatty acids (SCFAs) produced by gut microbiota, and this may play a key cancer-preventative role. One study identified cancer- preventative pathways via computer modelling of mushrooms and human gut microbiota.
Conclusion
In mice, mushrooms resulted in favourable changes to tumour measurements, SCFA activity and gut microbiota gene pathway enrichment. Inconsistent changes were reported in other outcomes, and the complexity of the gut microbiome and immunity makes these findings difficult to interpret. Results from murine studies are difficult to extrapolate to humans, and human studies are lacking. In silico research may prove invaluable as technologies progress, and it is suggested that cancer clinical trials using mushrooms consider taking stool samples to analyse for gut microbiota and SCFAs. The findings of this review are insufficient to inform any kind of treatment protocol, and further research is recommended.
