The relationship between the human microbiome, diet and health is increasingly understood thanks to recent research that highlights its impact on inflammatory and metabolic diseases and pregnancy. Studies published in ‘Nature‘ and ‘Nature Medicine’ have shown how the activity of the microbiome and its interaction with the human host influence pathologies such as inflammatory bowel disease (IBD), prediabetes and the risk of preterm birth.
A Stanford Medicine study, published in Nature Metabolism, identifies how byproducts of fiber digestion, specifically short-chain fatty acids such as propionate and butyrate, exert an epigenetic effect on gene expression. These molecules, produced by the gut microbiome, not only modulate cell proliferation and apoptosis, but also have a significant anticancer impact.
Michael Snyder, professor of Genetics at Stanford and leader of the research, highlights the importance of this finding: «We found a direct link between fiber consumption and the modulation of genetic function with anti-cancer effects. “This mechanism could be widespread, since short-chain fatty acids can travel throughout the body.”
When we eat fiber, the gut microbiome produces short-chain fatty acids. These compounds are more than a source of energy for us: they have long been suspected of indirectly affecting genetic function. The researchers tracked how the two most common short-chain fatty acids in our gut, propionate and butyrate, altered gene expression in healthy human cells, in treated and untreated human colon cancer cells, and in mouse intestines.
They found direct epigenetic changes in specific genes that regulate cell proliferation and differentiation, along with apoptosis, or preprogrammed cell death processes, all of which are important in interrupting or controlling the uncontrolled cell growth that underlies cancer.
“We found a direct link between fiber consumption and the modulation of gene function that has anticancer effects, and we believe that this is likely a global mechanism because the short-chain fatty acids that result from the digestion of fiber can travel throughout the body,” explains Snyder.
“In general, people’s diets are very low in fiber, which means that their microbiome is not fed properly and cannot produce as many short-chain fatty acids as it should. “This is not good for our health.”
Given the worrying rates of colon cancer in younger adults, the study’s findings could also stimulate debate and research into the possible synergistic effects of diet and cancer treatment.
“By identifying the genetic targets of these important molecules, we can understand how fiber exerts its beneficial effects and what goes wrong during cancer,” adds Snyder.
On the other hand, the Integrative Human Microbiome Project (iHMP) has shed light on the interaction between the microbiome and the human host under specific conditions.
In the case of IBD, researchers from Harvard University and the Broad Institute of MIT analyzed 132 patients and a healthy control group. They identified alterations in the intestinal microbiome, changes in the host and in molecules derived from the microbiome that are related to outbreaks of diseases such as ulcerative colitis and Crohn’s disease.
Complete remission
“Our results allow us to predict future outbreaks of the disease, which could facilitate early interventions or therapies that promote complete remission,” says Curtis Huttenhower, leader of the study.
A second study led by Michael Snyder and his team at Stanford explored how microbial interaction in prediabetes can predict the transition to type 2 diabetes. By analyzing 106 people over four years, the researchers identified molecular and microbial patterns that could serve as early markers of the disease.
These findings reinforce the importance of a high-fiber diet and a healthy microbiome in preventing and managing various diseases. Furthermore, they highlight how deep analysis of the microbiome and its interaction with the human host can pave the way towards new personalized therapies and prevention strategies.
Science continues to show that taking care of our microbiome is not just a fad, but a necessity to ensure a better quality of life and long-term well-being.
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