It is well established that diet influences health and disease, but the mechanisms underlying this effect are not fully understood. Shedding light on the diet-health connection, a team led by researchers at Baylor College of Medicine reports today in The American Journal of Clinical Nutrition an association between diet quality and microbiome composition in human colonic mucosa. The researchers 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. They propose that modifying the microbiome through diet may be a 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,” said corresponding 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 reduced risk of pancreatic cancer.”
Diet is considered a principal factor influencing the structure of the microbial community in the gut, which in turn significantly affects the ability of beneficial or harmful microbes to colonize it. 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, Jiao explained.
“One new contribution to this work is that we looked at the microbiome associated with colonic mucosa,” Jiao said. “Most other studies of the human gut microbiome have used fecal samples. 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.”
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 50- to 75-year-old participants 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. They reported their dietary consumption using a food frequency questionnaire before the colonoscopy