The human gut is home to an abundance of microorganisms - a whopping 1014 microbes to be exact! Altogether, the human gut microbiota harbors 100 times more genomic material than the human genome, a situation so profound that it has been referred to as the “second genome.” (1) Diet is one of the fundamental factors influencing gut microbial gene expression in the human gut. In fact, a recent study titled “Plant-Derived Exosomal MicroRNAs Shape the Gut Microbiota” indicates that the genomic material in plant foods interacts with the genome of the gut microbiota, shaping its composition and the health and function of the gut itself.
A brief review of a profound study
The research I mentioned above contains profound findings, but the wording can get confusing, so I’d like to break down the key messages of the study in this article. First, let’s briefly cover a bit of plant science.
What are plant exosomes?
Plant cells house edible nanoparticles, fine particles between 1 and 100 nanometers in diameter. These edible nanoparticles contain miRNA (a small, non-coding RNA molecule that functions in the regulation of gene expression), bioactive lipids, and proteins. These compounds are released in structures called exosomes and thereby serve as extracellular messengers mediating cell-to-cell communication in plants. However, it turns out that these exosomes don’t just influence plant physiology; when we consume plants, the plant exosomes interact with our own bodies, including our gut microbiota.
Plant genetic material promotes a healthy gut
In this study, the researchers administered plant-derived exosome-like nanoparticle (ELN) RNA (a type of genetic material) from ginger rhizomes to mice. They found that the ELN RNA was preferentially taken up by gut bacteria, particularly members of the lactic-acid producing bacterial family Lactobacillaceae, resulting in the proliferation of these beneficial bacteria while also regulating the growth of other gut bacteria. Furthermore, the genetic material in the ELN targeted various genes in Lactobacillus rhamnosus, an important member of the Lactobacillaceae family, that are involved in immune regulation and maintenance of the gut barrier. This effect suggests that edible plant exosomes may help prevent and heal intestinal permeability (aka “leaky gut”). Finally, the ginger ELN RNA also alleviated colitis in the mice, suggesting that a plant-food rich diet influences the risk of gastrointestinal inflammation at the gene level.
Genetically-modified plants and the gut microbiota
An important question brought up by this research is, if the genetic material in natural plant foods has beneficial effects on our gut microbiota, what effects might genetically-modified plant foods have? This is a concerning topic that researchers have only barely scraped the surface of. We do know from animal models that horizontal gene transfer occurs between genetically-modified organisms and gut microbiota. (2) In fact, consuming corn genetically modified to contain an insecticidal toxin from the bacterium Bacillus thuringiensis (Bt toxin) may horizontally transfer Bt toxin genes to our gut microbiota, creating a living “pesticide factory” in our digestive systems. Indeed, Bt toxin has been found in human blood, indicating that it does make its way from the gut into our systemic circulation. (3) While more research is needed, I recommend that people avoid eating genetically modified organisms because the long-term health risks, including those to the gut microbiota, are essentially unknown.
Takeaway: Eat more (non-GMO) plants to support your gut health!
While this research was conducted in mice, it suggests that edible plant genetic material may affect the biology of our gut bacteria and, subsequently, our gut health and overall well being. It is well understood that our hunter-gatherer ancestors ate a plethora of plant foods; in addition to supplying vitamins, minerals, and phytonutrients, these plants may also have shaped their gut microbiota (and thus their overall health) via unique exosome genetic material. A lack of plant foods in our diets, a feature characteristic of the Standard American Diet, may thus deprive us of the genetic programming our gut microbes need to create a healthy, resilient gut. To improve your gut health, try to eat as wide a variety of plant foods as possible. Start by trying to incorporate one new plant food into your diet each week. I’ve personally found that joining a CSA (community supported agriculture), a program offered by many organic and sustainable farms that provides you with fresh produce on a regular schedule, is an excellent way to incorporate new plant foods into your diet.