A new study published in the journal Cell Host and Microbe has discovered that a fatty diet promotes the growth of the microbes that boost digestion and absorption. The research, which is one of the first to focus on microbes in the upper gastrointestinal tract, found that a calorie-dense western diet can enhance expansion of microbes which, by enabling the production and secretion of digestive enzymes into the small bowel, break down dietary fat and enable calorie-dense foods to be rapidly absorbed.
“These bacteria are part of an orchestrated series of events that make lipid absorption more efficient,” said the study’s senior author, Eugene B. Chang, director of the NIH Digestive Diseases Research Core Center at the University of Chicago Medicine. “Few people have focused on the microbiome of the small intestine, but this is where most vitamins and other micronutrients are digested and absorbed.”
“Our study is one of the first to show that specific small-bowel microbes directly regulate both digestion and absorption of lipids,” he added. “This could have significant clinical applications, especially for the prevention and treatment of obesity and cardiovascular disease.”
The study involved germ-free, chamber-bred mice that had no intestinal bacteria, and “specific pathogen free (SPF)” mice, which were healthy but harboured non-disease causing microbes. The germ-free mice were unable to digest or absorb high-fat foods even when fed a high-fat diet, and did not gain weight. The researchers found increased lipid levels in their stool.
The SPF mice that received a high-fat diet did experience weight gain. This diet quickly boosted the abundance of certain microbes in the small intestine, including microbes from the Peptostreptococcaceae and Clostridiaceae families. “Our study found that, at least in mice, a high-fat diet can profoundly alter the microbial makeup of the small intestine,” said Chang. “Certain dietary pressures, such as calorie-dense foods, attract specific bacterial strains into the small intestine. These microbes are then able to allow the host to digest this high-fat diet and absorb fats.”
The study’s authors concluded that: “This work has important implications in developing approaches to combat obesity.” Kristina Martinez-Guryn, one of the lead authors said: “The most important takeaway overall is the concept that what we eat – our diet on a daily basis – has a profound impact on the abundance and the type of bacteria we harbour in our gut. These microbes directly influence our metabolism and our propensity to gain weight on certain diets.”
Although only an early study, Martinez-Guryn added, “our results suggest that maybe we could use pre- or probiotics or even develop post-biotics to enhance nutrient uptake for people with malabsorption disorders, such as Crohn’s disease.”