Small fragments of genetic material from vegetables we eat could be altering our genes, according to a study carried out by scientists in China.
The researchers, from Nanjing University, found plant microRNAs (small fragments of RNA) in blood samples taken from humans, and a number of other plant-eating animals. The two most common types of microRNA detected in the blood samples (MIR156a and MIR168a) are found in rice and cruciferous vegetables, such as broccoli; suggesting the microRNAs had come from foodstuffs.
Professor Chen-Yu Zhang, senior author of the study, said in an email to MSNBC: 'Plant microRNAs may represent essential functional molecules in food and herbal medicine, and also provide a novel therapeutic strategy for the treatment of diseases'.
MicroRNAs are known to be a useful way of fine-tuning gene expression in the body, or indeed in plants. However, until now plant microRNAs had been thought to only be effective at regulating plant genes, and similarly human microRNAs effective only on human genes.
The idea that microRNAs in food could survive being digested is also novel. However, this was confirmed by the researchers when they detected plant microRNAs in the blood of mice that had been fed rice.
Professor Zhang, whose research was published in Cell Research, theorised that if the plant microRNAs were able to make it through to the bloodstream, they might also be controlling the expression of genes in the body.
This theory was supported when the researchers found that injecting mice with MIR168a caused an increase in low-density lipoprotein (LDL) – often referred to as 'bad' cholesterol. This was due to the MIR168a silencing a gene that would usually help break down LDL.
Professor Zhang believes that microRNAs from plants we eat could be affecting us, stating that the rise in LDL caused by MIR168a could 'possibly increase the risk of metabolic syndrome'.
Other researchers are more sceptical. Dr Petr Svoboda, of the Institute of Molecular Genetics in the Czech Republic told MSNBC that levels of plant microRNAs in humans are typically lower than those used in this study, stating that the low levels are unlikely to have any physiological effect in the human body.
In any case, some commentators have predicted that this research may lead to scientists designing therapeutic plants and diets in the future. Professor Ed Stellwag, an evolutionary biologist at East Carolina University told New Scientist: 'You can bet this will create an absolute flurry of research activity as scientists race to discover how genetic information in our food changes our health'.