Dietary Fiber Better Digested With The Help Of Gut Bacteria
January 20, 2014

Researchers Identify Process By Which Gut Bacteria Process Dietary Fiber

redOrbit Staff & Wire Reports - Your Universe Online

Scientists from the US, the UK, Canada and Sweden have discovered how our bodies process dietary fiber, a substance which can improve digestion and help people control their weight by making them feel full faster.

In the January 19 edition of the journal Nature, researchers from the Royal Institute of Technology (KTH), the University of British Columbia (UBC), the University of York and the University of Michigan Medical School explain how the complex dietary carbohydrates found in fruits and vegetables are metabolized by gut bacteria.

According to the researchers, there are roughly 100 trillion microbiota (bacteria living in human intestines) in the average person’s body, and they all play a vital role in human metabolism and overall well-being. One specific type of gut bacteria, Bacteroidetes, is responsible for digesting a type of complex sugar known as xyloglucans.

This sugar comprises up to one-fourth the dry weight of dietary fruit and vegetables, including onions, lettuce and tomatoes, and fully understanding the processes by which microbiota digest complex carbohydrates can help shed new insight on several different nutritional issues, such as the effect of prebiotics and probiotics on the body.

“While they are vital to our diet, the long chains of natural polymeric carbohydrates that make up dietary fiber are impossible for humans to digest without the aid of our resident bacteria,” explained senior author and UBC professor Harry Brumer. “This newly discovered sequence of genes enables Bacteroides ovatus to chop up xyloglucan, a major type of dietary fiber found in many vegetables.”

B. ovatus and its complex system of enzymes provide a crucial part of our digestive toolkit,” he added. “The next question is whether other groups in the consortium of gut bacteria work in concert with, or in competition with, Bacteroides ovatus to target these, and other, complex carbohydrates.”

Based on a survey of public genome data from 250 adults, Brumer and his co-authors reported that approximately 92 percent of the population possesses bacteria with a variant of this gene sequence. The findings could lead to tailored gut bacteria transplants in order to improve intestinal health following illness or antibiotic use.

“Despite our omnivorous diet, humans aren't well equipped to eat complex plant matter; for this we rely on our gut bacteria. This work is helping us to understand the science of that process,” said professor Gideon Davies, who led the research at the University of York.

“The possible implications for commerce and industry extend beyond the realm of human nutrition, however,” he added. “The study of how enzymes break down plant matter is also of direct relevance to the development of processes for environmentally-friendly energy solutions such as biofuels.”