Diet is important in maintaining human health, but its underlying mechanism is not yet fully understood. Now, a team of researchers sheds light on the connection of diet and health, and it has something to do with the microbiome composition in human colonic mucosa.
The investigators at Baylor College of Medicine report the link between diet quality and microbiome structure and composition in the colonic mucosa, providing insight into the mechanism behind how diet impacts health.
It is known that the intestinal microbiome plays an important role in modulating chronic disease risk. The study, which was published in The American Journal of Clinical Nutrition, shows that diet plays an equally significant role in shaping the microbiome, hence, affects overall health.
The researchers found that a high-quality or a healthy diet is associated with potentially beneficial bacteria and in contrary, a poor diet is linked to an increase in potentially pathogenic bacteria. Hence, they encourage that one way to modify the microbiome is through diet, which can be an approach to lower chronic disease risk.
The gut microbiome
The human gut microbiome consists of tens of trillions of resident microorganisms, including bacterial There are more than 1,000 different species of bacteria with more than 3 million genes, which is 150 times more than the human genes.
Microbiome in human gut. Image Credit: Alpha Tauri 3D Graphics / Shutterstock
Recently, a growing body of knowledge proves the benefits of gut microbiome to health. There is also a growing interest in the capability to modify the gut microbiota. For instance, a change in diet alters the microbial composition.
Diet is a major factor affecting the microbial community structure in the gut. In turn, it can affect the ability of both the beneficial and harmful microorganisms to colonize it. Aside from that, the human gut flora can impact nutrient uptake, energy harvest, vitamin synthesis, carcinogen metabolism, chronic inflammation, metabolic response, and body’s immune system response. All these factors impact the risk of developing chronic diseases.
"One new contribution to this work is that we looked at the microbiome associated with colonic mucosa. Most other studies of the human gut microbiome have used fecal samples,” Dr. Li Jiao, associate professor of medicine-gastroenterology and member of the Dan L Duncan Comprehensive Cancer Center at Baylor College of Medicine, explained.
“We looked at colon mucosal-associated microbiome because we know that this microbiome is different from that in the fecal samples, and it is said to be more related to human immunity and the host-microbiome interaction than the microbiome in fecal samples,” she added.
Dietary quality affects gut flora
To land to the findings of the study, the researchers utilized modern sequencing techniques to study the bacterial community composition living in colonic mucosal biopsy samples. They analyzed the bacterial structure using the 16S rRNA gene (V4 version) sequencing in 97 colonic mucosal biopsies obtained from colonoscopy samples of different colon segments from 34 patients. These patients, who were healthy and polyp-free, underwent colonoscopy at the Michael E. DeBakey Veterans Affairs Medical Center in Houston from 2013 to 2017.
The team found that a good quality diet, which is recommended by the Dietary Guidelines for Americans, positively impacts the abundance of beneficial bacteria in the gut. These bacteria species are those with anti-inflammatory properties, which can help reduce the risk of chronic diseases.
The Dietary Guidelines for Americans recommends eating a diet with most of the calories from grains, vegetables, fruits, lean meats, poultry, fish, and low-fat dairy products.
On the other hand, eating a poor-quality diet has been linked to the abundance of potentially-harmful bacteria, including Fusobacteria, a type of bacteria associated with colorectal cancer.
The team also wants to investigate how a potentially harmful gut microbiome in people who consume an unhealthy diet would benefit from diet modification and use of prebiotics or probiotics.
The researchers said that nonmodifiable factors like aging ang genetics also influence disease risk, but they can’t be modified. Meanwhile, diet is an excellent factor that can be modified, providing a good tactic to develop a microbiome to promote overall health.
Liu, Y., Ajami, N., El-Serag, H., Hair, C., Graham, D., White, D., Chen, L., Wang, Z., Plew, S., Kramer, J., Cole, R., Hernaez, R., Hou, J., Husain, N., Jarbrink-Sehgal, M., Kanwal, F., Ketwaroo, G., Natarajan, Y., Shah, R., Velez, M., Mallepally, N., Petrosino, J., and Jiao, Li. (2019). Dietary quality and the colonic mucosa–associated gut microbiome in humans. The American Journal of Clinical Nutrition. https://academic.oup.com/ajcn/advance-article-abstract/doi/10.1093/ajcn/nqz139/5530748?redirectedFrom=fulltext