Research results published in the journal Cell Research provide evidence that small bits of genetic material from ingested plants may regulate gene expression in animals. (for the original paper, see Ref 1 below; and summaries of these findings can be found in refs. 2 & 3 below)
These small bits of plant genetic material are called micro RNAs (miRNA).
Briefly, these very small pieces of RNA are found in both animals and plants. They “…were recently revealed as master chief regulators of gene expression in all organisms.” (from ref 2 below)
These micro RNAs regulate gene expression by interfering with translation. They do so by binding to complementary regions of specific message RNAs (mRNAs) to prevent translation of these mRNAs into proteins.
In other words, miRNAs may inhibit or prevent the final outcome of gene expression by interfering with the final step, that is, protein biosynthesis.
Because of this, small RNAs have been recognized as significant factors in the regulation of gene expression in both animals and plants.
But is it possible that the small RNAs present in the plant material you eat may actually affect the regulation of your own genes?
This is the question was investigated by researchers at the Nanjing University of Life Sciences, and their answer appears to be: YES!
They also investigated the presence of these plant-derived miRNAs in mice fed with either rice or mouse chow. The rice-fed mice had a higher levels of plant-derived miRNAs compared to the mice fed with chow. And when the researchers added plant miRNAs to the chow, this resulted in higher plant miRNAs in the mouse serum.
Cooking the rice had no effect. That is, the plant-derived miRNAs apparently survived not only the digestive process, but also cooking temperatures.
Apparently what happens is that the plant-derived miRNAs are absorbed by the cells in the intestines. These intestinal cells then package the miRNAs and secrete them into the bloodstream.
What are the implications?
Well, of course, the main implication is that the cooked or uncooked plant material you eat may actually affect the regulation of some of your genes through the effects of plant-derived miRNAs.
Does meat also contain miRNAs? You bet! Indeed, meat miRNA content may be at much higher levels compared to plant material.
All of this adds a whole new twist to the phrase “You are what you eat”.
If natural miRNAs that you ingest can be absorbed by your body and have effects on your gene regulation, what about artificial genes present in GMOs?
Indeed, one of the new strategies that genetic engineers have been using in pest control is through the use of small RNAs in genetically-modified crop plants to interfere with the production of specific proteins in insects and nematodes. (see ref 2)
Now that there is evidence that such small RNAs may actually be absorbed from ingested cooked or uncooked plant material and may be active in humans could have major implications on the use transgenic plants for food.
Though the implications of this report are far-reaching, it’s important to keep in mind that it’s a single study.
I’m sure other labs are actively engaged in attempting to confirm and to expand on these results.
Nevertheless, the more things we learn about the nature of plants, the more things get interestinger and interestinger.
1. Zhang, L., et al. (2011) “Exogenous plant MIR168a specifically targets mammalian LDLRAP1: evidence of cross-kingdom regulation by microRNA.” Cell Research, advance online publication 20 September 2011; doi: 10.1038/cr.2011.158.
2. Vaucheret, H. and Y. Chupeau (2011) “Ingested plant miRNAs regulate gene expression in animals.” Cell Research, advance online publication 25 October 2011; doi: 10.1038/cr.2011.164. (Full Text)
3. Science Daily, (Sept. 19, 2011) “Plant miRNAs Could Enter Host Blood and Tissues Via Food Intake, Study Suggests.” (Full Text)
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