**5.2 Stability and survival of plant miRNAs to the gastrointestinal tract in mammals**

In a second approach to cross-kingdom approach, as far as was known, there was no major evidence demonstrating the survival of exogenous miRNAs to the gastrointestinal (GI) system, blood, or organs in mammals. Plant-derived MIR172 was detected in a range of 2–72 hours and remained stable in organs, tissues, feces, and blood in mice after being fed total RNA from *Brassica oleracea* in amounts between 10 and 50 μg, administered orally, suggesting the survival of exogenous miRNAs to the GI system, organs, and blood in mammals [36]. Subsequently, in another study in humans [10], 16 miRNAs from plants were evaluated and detected after ingestion (ath-MIR156a, ath-MIR157a, ath-MIR162a, ath-MIR167a, ath-MIR168a, ath-MIR172a, ath-MIR172a, ath-MIR390a, osa-MIR528, ppt-MIR894, ath-MIR166a, ath-MIR158a, ath-MIR159a, ath-MIR160a, ath-MIR163a, ath-MIR169a, ath-MIR824). The concentrations of plant miRNAs were measured by qRT-PCR, in nine volunteers administered orally with 2.5 L of watermelon juice and 2.5 kg total mixture of other fruits, finding the presence of exogenous miRNAs (MIR156a, MIR157a, MIR162a, MIR167a, MIR168a, MIR172a, MIR390a, MIR528, MIR894, and MIR166a) in serum for up to 9 hours, demonstrating that a variety of exogenous plant miRNAs can be found in human plasma following ingestion.
