The study – published in Cell Host & Microbe – reveals that certain strains of gut bacteria can increase the absorption of dietary fats, allowing the host organism to extract more calories from the same amount of food.
Led by senior author John Rawls from the University of North Carolina, USA, the research team explains that the presence of Firmicutes bacterial species in the gut is ‘instrumental’ in increasing fat absorption. The findings indicate that the profile of a person’s microbiota can have a very real effect on their ability to absorb fat and thereby harvest more calories from the diet, said the researchers.
"This study is the first to demonstrate that microbes can promote the absorption of dietary fats in the intestine and their subsequent metabolism in the body," said Rawls. "The results underscore the complex relationship between microbes, diet and host physiology."
"Our findings indicate that the gut microbiota can increase the host's ability to harvest calories from the diet by stimulating fat absorption," added lead researcher Dr Ivana Semova. "Another implication is that diet history could impact fat absorption by changing the abundance of certain microbes, such as Firmicutes, that promote fat absorption."
Rawls said that by obtaining a greater understanding of how specific gut bacteria are able to stimulate absorption of dietary fat, “we may be able to use that information to develop new ways to reduce fat absorption in the context of obesity and associated metabolic diseases, and to enhance fat absorption in the context of malnutrition."
The study was carried out in zebrafish, which are optically transparent when young. By feeding the fish fatty acids tagged with fluorescent dyes the researchers were able to directly observe the absorption and transport of fats in live animals, they explained.
The group then pioneered methods to grow the zebrafish larvae in the presence or absence of gut microbes.
By combining these approaches, the team was able to determine that the Firmicutes strain is instrumental in increasing fat absorption – suggesting that bacteria in the gut can have a big influence on the host's ability to absorb fat and thereby harvest calories from diet.
Further research has suggested that a high-fat diet promotes the growth of Firmicutes, the researchers said, which would then resulting in further fat absorption.
Though the study involved only fish, not humans, it offers insights that could help inform new approaches to treating obesity and other disorders, said the authors.
"The unique properties of zebrafish larvae are helping us develop a better understanding of how the intestine functions with the goal of contributing to ongoing efforts to reduce the impact of diseases associated with altered lipid metabolism, such as diabetes, obesity, and cardiovascular disease,” said Steve Farber of the Carnegie Institution, who also worked on the study.
“Our collaboration … is now focused on how specific gut bacteria are able to stimulate absorption of dietary fat. We hope to use that information to develop new ways to reduce fat absorption in the context of human diseases," Farber added.
Source: Cell Host & Microbe
Volume 12, Issue 3, Pages 277-288, doi: 10.1016/j.chom.2012.08.003
"Microbiota Regulate Intestinal Absorption and Metabolism of Fatty Acids in the Zebrafish"
Authors: Ivana Semova,Juliana D. Carten,Jesse Stombaugh,Lantz C. Mackey,Rob Knight,Steven A. Farber,John F. Rawls