Food-Derived Xeno-microRNAs: Influence of Diet and Detectability in Gastrointestinal Tract-Proof-of-Principle Study

Scope Diet is amongst the most crucial factors contributing to the multistep process of carcinogenesis. The role of exogenous microRNAs (miRNAs) is still debatable. In this proof-of-principle work, the presence of miRNAs in a variety of foods, its stability to processing, and detectability in GI mucosa and feces are studied and the effect of short-term diet on human- or plant-derived miRNAs in feces and blood is examined. Methods and results Animal and plant miRNAs are detected in all foods irrespective of processing. Animal-derived foods showed the highest miRNA level and the lowest is found in cheese and milk. The impact of the short-term vegetarian or meat-rich diet on blood and feces miRNA is evaluated in healthy subjects using qPCR and Affymetrix profiling. Diet is not associated with changes in ultraconserved miRNAs. However, a vegetarian diet is associated with an increase of miR-168 in feces but not in blood. Overall, plant miR-168 is detectable in normal GI mucosa and in colorectal cancer. Conclusions Food provides a great source of miRNAs and diet may be associated with changes in xenomiRs. Plant-derived miR-168 is ubiquitously present in feces, normal mucosa, and cancer. Further studies are needed to evaluate the functional interaction between diet-derived miRNAs and GI tract.