NEW STUDY. The feeding habits of brown bears go from extreme energy consumption during the summer months to a zero energy intake during winter hibernation. In a unique study of free-ranging brown bears, Swedish researchers were able to show that the bears’ dietary variation goes hand-in-hand with dramatic changes in the animal’s gut microbiota – a finding that may provide increased knowledge of how the gut microbiota affects our metabolism.
Professor Fredrik Bäckhed and his research colleagues have shown in several high-profile studies that metabolism related diseases such as diabetes, obesity and coronary heart disease are associated with bacterial changes in our guts.
Wild brown bears
In what Fredrik Bäckhed describes as “classic basic research”, he and his colleagues have mapped the seasonal variation in the gut microbiota, in sixteen wild brown bears.
The idea for the study comes from insights in dietary habits of brown bears that changes from an extreme energy intake during the summer to complete cessation during the winter, when the bear hibernates. Studies have shown that the brown bear is insulin sensitive during the summer, while it develops insulin resistance during the winter months, in order to reduce energy consumption in the body and save energy for the brain.
Seasonal changes
In the present study, which involved researchers from the Scandinavian Brown Bear Research Project, Örebro University and Duke University, it was shown that the brown bear’s gut microbiota significantly changed per season.
“During winter hibernation, the concentration of several specific molecules in the bear’s blood increase, a process that we believe reflects changes in the gut microbiota. When summer is well underway, the omnivorous bear eats varied diet, which increase microbial diversity”, says Fredrik Bäckhed.
Mice with bear microbiota
In an experiment where the bears’ gut microbiota was transferred to germ-free mice, the researchers were able to observe that mice receiving the bears’ summer gut microbiota increased their capacity to store fat.
“Especially interesting was the notion that the mice became fatter without developing insulin resistance, similar to the bears from where the microbiota was obtained,” says Bäckhed,
“The study is classic basic research and more studies are needed to arrive at any practical applications. But the bear study provides new knowledge on how gut microbiota affects our metabolism, a finding that may help us to develop bacteria based treatments in the future.”
The article The gut microbiota modulates energy metabolism in the hibernating brown bear Ursus arctos will be published in the online journal, Cell Reports, on February 4.
Link to article: http://www.cell.com/cell-reports/fulltext/S2211-1247(16)00047-4
For more information on the Scandinavian Brown Bear Research Project go to: http://bearproject.info/?lang=sv_se
TEXT: KRISTER SVAHN
Photo at top: Ole Fröbert
