Diet and microbiome link established: Healthy diet may reduce chronic disease risk, study says
A low-quality diet was associated with potentially harmful gut bacteria, while a high-quality diet was linked to beneficial gut bacteria
17 Jul 2019 --- Research has found an association between diet quality and microbiome composition in human colonic mucosa. The study from Baylor College of Medicine in Houston, Texas, US found that a high-quality diet is linked to more potentially beneficial bacteria, while a low-quality diet is associated with an increase in potentially harmful bacteria. Published in The American Journal of Clinical Nutrition, the study sheds light on the diet-health connection with the researchers proposing that modifying the microbiome through diet could be part of a strategy to reduce the risk of chronic diseases.
“In this study, rather than looking at individual diets, we focused on dietary patterns as defined by the Healthy Eating Index (HEI)-2005 and how they relate to the microbiome,” says study author Dr. Li Jiao, Associate Professor of Medicine-Gastroenterology and member of the Dan L Duncan Comprehensive Cancer Center at Baylor College of Medicine. “In a previous study, we found that HEI-2005 is associated with a reduced risk of pancreatic cancer.”
Diet is considered to be a principal factor influencing the structure of the microbial community in the gut, which in turn affects the ability of beneficial or harmful microbes to colonize it, the researchers say. The human gut microbiome also influences nutrient uptake, synthesis of vitamins, energy harvest, chronic inflammation, carcinogen metabolism and the body’s immune and metabolic response – factors that can affect disease risk, notes Jiao.
“One new contribution to this work is that we looked at the microbiome associated with colonic mucosa,” Jiao says. “Most other studies of the human gut microbiome have used fecal samples. We looked at the colon mucosal-associated microbiome because we know that this microbiome is different from that in the fecal samples. It is also said to be more related to human immunity and the host-microbiome interaction than the microbiome in 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.In the study, the researchers used next-generation sequencing techniques to analyze the type and abundance of bacteria present in colonic mucosal biopsies. The samples were obtained endoscopically from enrolled consenting participants age 50-75, who had a colonoscopy at the Michael E. DeBakey Veterans Affairs Medical Center in Houston between 2013 and 2017. The participants were polyp-free and seemingly healthy. The participants reported their dietary consumption using a food frequency questionnaire before the colonoscopy.
The team of researchers discovered that a high-quality diet – such as the one recommended by the Dietary Guidelines for Americans which is high in fruits, vegetables and whole grains, and low in added sugar, alcoholic beverages and solid fats – is associated with a higher concentration of beneficial bacteria, such as those with anti-inflammatory properties. A poor-quality diet, on the other hand, is associated with more potentially pathogenic bacteria, such as Fusobacteria, which has been linked to colorectal cancer.
The researchers propose that the effect that diet has on the structure of bacterial communities in human colonic mucosa can lead to modifications of innate immunity, inflammation and the risk of chronic diseases.
Going forward, the researchers will conduct more trials to confirm the study findings in a larger study population. In addition, they want to investigate how bacterial products (metabolites) such as short-chain fatty acids or secondary bile acids, can modify tissue microenvironment into one that inhibits or promotes either tumor growth or the development of other diseases.
Moreover, Jiao and her colleagues are interested in investigating how the unfavorable gut microbiome in individuals consuming a poor diet would respond to tailored dietary intervention using diet, prebiotics or probiotics, as previous studies have produced mixed results.
“Other factors, such as aging, genetics or certain medications, also influence the risk of disease but we cannot modify them,” Jiao says. “Diet, on the other hand, can be modified and thus provides a strategy to develop a microbiome that promotes healthy living. We suggest that modifying the microbiome through diet may be a part of a plan to reduce the risk of chronic diseases.”
Edited by Kristiana Lalou
