GENE expression is affected by gut microbiota changes induced by diet, new research has revealed. It is currently known that while the DNA composition of genes is relatively fixed, changes in the environment are able to trigger a gene response, altering their expression via the utilisation of chemical tags located along the DNA, switching them on and off. Furthermore, although it has been discovered that the gut microbiota produce many metabolites that influence health and disease, the framework of molecular mechanisms that underlie this are, at present, unknown.
The team at the University of Wisconsin-Madison, Madison, Wisconsin, USA, sought to unveil the role of gut microbes in health, raising mice on two different diets: a diet rich in simple sugars and fats (emulating a Western diet) and one rich in plant carbohydrates (emulating a human diet rich in fruits and vegetables). A comparison of the two mice groups revealed that the Western-style diet prevented a significant amount of the epigenetic changes that occurred in the plant-rich diet. It was further discerned that a particular group of short-chain fatty acids, produced when gut bacteria ferment nutrients from plants, were partly responsible for communicating with the cells of the host mice through the epigenome.
To further test the role played by the short-chain fatty acids, the researchers raised a group of mice in a germ-free environment so they had virtually no gut microbiota. When these mice were provided with short-chain fatty acid supplements, the epigenetic changes seen in normal mice raised on a plant-rich diet were restored. One of the researchers, Prof John Denu, Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA, noted that these findings helped demonstrate that “the collection of three short-chain fatty acids produced in the plant-based diet are likely major communicators. We see that it is not just the microbe. It is microbial metabolism.”
A final intriguing discovery obtained from this research was the idea that communication between the gut microbiome and the host extended further than the colon, with evidence uncovered suggesting communication with cells in the fatty tissue of the gut and liver.
The researchers explained the differing impacts of the diets by suggesting that foods rich in fat and sugar are not necessarily a good source of nutrients for gut microbes, leading to a reduction in the diversity of the gut microbiome and consequently, decreased communication with the epigenome. Prof Denu concluded: “We are starting to understand the mechanism of how and why diet and the microbiome matter.”