Table 2.

Summary of evidence regarding dietary microRNA uptake and functionality in consumers.

Dietary microRNA Uptake and Function in Mammalian Consumers?
Evidences Against	Exogenous levels in serum are inconsistent and typically low. Various feeding studies from different labs failed to show absorption of dietary microRNAs. Target suppression is shown only in the initial study, and was not replicated by another group. In silico analyses suggest plant microRNA reads in animal tissue could be due to contamination.
Evidences For	Oral uptake of exogenous microRNAs is well-characterized in nematodes and insects (indirect evidence). Detection of fungal, bacterial, and plant derived microRNAs in mammalian circulation is consistently reported. MIR168a target suppression shown in the initial study. Detection of MIR172 in circulation and various organs in mice fed cabbages. Report of Bovine milk microsome-derived microRNAs being absorbed in humans and mice. Detection of honeysuckle derived small RNA MIR2911 in mouse circulation and urine, and report of antiviral functions of MIR2911 in vivo in mice. Report of tumor suppressing effect from orally fed synthetic tumor suppressor microRNAs with plant microRNA chemistry.