(Before It's News)
Study only finds microRNA in small amounts
The new study from the National Food Institute and partners consists of two parts: In the first part the researchers have analyzed available microRNA sequencing data from 824 human blood and tissue samples to see if they contain genetic material that could have been derived from food.
“The study shows that genetic material from our food is not absorbed into our bodies.”
The analysis shows that microRNAs from other organisms than humans are only present in 17% of the tissue samples and in 69% of the blood samples, but in negligible amounts (0.001%) compared to the total amount of microRNA present in the samples. Moreover, the overwhelming majority of the identified foreign microRNA comes from organisms, which humans rarely eat, but which are often used in laboratory experiments and animal testing, such as rats and insects.
In the second part researchers studied blood samples from animals that have been fed certain feed to see whether the samples contain microRNA from that particular feed. The researchers have been unable to find evidence that microRNA from the feed had entered the animals’ blood stream.
More @ The body does not absorb genetic material from our food – DTU Food
Survey of 800+ datasets from human tissue and body fluid reveals XenomiRs are likely artifacts
miRNAs are small 22 nucleotide RNAs that can post-transcriptionally regulate gene expression. It has been proposed that dietary plant miRNAs can enter the human bloodstream and regulate host transcripts, however these findings have been widely disputed. We here conduct the first comprehensive meta-study in the field, surveying the presence and abundances of cross-species miRNAs (xenomiRs) in 824 sequencing datasets from various human tissues and body fluids. We find that xenomiRs are commonly present in tissues (17%) and body fluids (69%), however the abundances are low, comprising 0.001% of host human miRNA counts. Further, we do not detect a significant enrichment of xenomiRs in sequencing data originating from tissues and body fluids that are exposed to dietary intake (such as liver). Likewise, there is no significant depletion of xenomiRs in tissues and body fluids that are relatively separated from the main bloodstream (such as brain and cerebro-spinal fluids). Interestingly, the majority (81%) of body fluid xenomiRs stem from rodents, which are rare human dietary contributions, but common laboratory animals. Body fluid samples from the same studies tend to group together when clustered by xenomiR compositions, suggesting technical batch effects. Last, we performed carefully designed and controlled animal feeding studies, in which we detected no transfer of plant miRNAs into rat blood, or bovine milk sequences into piglet blood. In summary, our comprehensive computational and experimental results indicate that xenomiRs originate from technical artifacts rather than dietary intake.
Wenjing Kang, Claus Heiner Bang-Bertelsen, Anja Holm, Anna Houben, Anne Holt Müller, Thomas Thymann, Flemming Pociot, Xavier Estivill, Marc R. Friedländer, RNA Journal 2017