Researchers discover reduced intestinal microbiota in bears that eat human food

American scientists have found that consuming human food has a clear effect on the microbiome of black bears. This is relevant as wild animals are increasingly eating human food.

Researchers from North Carolina State University and Northern Michigan University found that wild bears, which ingested a lot of processed foods, showed much less diversity in the microbial ecosystems in their intestines.whole bacteria found in the gastrointestinal tract).

“We would like to know if the same is true for wildlife, due to the increasing overlap between human habitats and areas where wildlife lives.”

“We know that a ‘Western’ diet can reduce microbial diversity in the intestines of humans, mice and other species, potentially adversely affecting their health,” said Erin McKenney, co-author of the study and assistant professor of applied ecology. at NC Stat. “We would like to know if the same is true for wildlife due to the increasing overlap between human habitats and areas where wildlife lives. It could affect their ability to get nutrients from their traditional wild diet if they stop. to eat human food. ‘

“To see if this is really true for wildlife, we wanted to assess the impact of human nutrition on the intestinal microbiome of wild mammals, and specifically black bears,” said lead author of the study Sierra Gillman, PhD student at the University of Groningen University of Washington.

The study was published in Journal of Mammalogy.

intestinal samples

The researchers conducted the study in the state of Michigan, where hunters are allowed to hunt bears “to entice” large quantities of human food, such as sugary breakfast cereals and sweets, to leave. Hunters can do this for weeks or months at a time in certain places to lure bears to those places over and over again. As a result, some bears follow a diet rich in human, highly processed foods for an extended period of time.

The researchers worked with guides who worked in the area to collect hair samples and intestinal samples from the wild bear population. Eventually, they were able to collect samples from a total of 35 bears.

The researchers then analyzed the bears’ hair, allowing them to assess each animal’s long-term diet. For example, they saw the extent to which each bear ingested sugar and corn, which are often found in processed foods.

In addition, the researchers processed the intestinal samples to identify the number of different types of microbes in each bear’s microbiome and how much of each type of microbe was present.

Intestinal biodiversity

Both measures of intestinal biodiversity were significantly lower in boars eating more processed foods. “For example, we discovered that the more human food black bears eat, and the longer they eat it, the less diverse their gut microbiome is,” Gillman says.

“The more human food black bears eat, and the longer they eat it, the less diverse their intestinal microbiome is.”

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“Sugar is very easy to digest,” McKenney says. ‘Many bacteria can consume it. In practice, this means that processed human food actually fewer provide nutrients to bacteria that specialize in breaking down fiber or other microavailable carbohydrates. These specialty bacteria struggle to compete with the other bacteria for sugar, and their niche in the food web is not sustainable if bears do not eat enough of their traditional diet. We believe that this is one of the ways in which the diversity of intestinal microbiota falling.’

And if gut biodiversity suffers when bears start consuming more human food, it will be harder for them to get the same amount of nutrients from non-human food if they return to a ‘wild’ diet, McKenney continues. ‘We do not know how quickly microbial species that break down fibers, for example, return.’

“Now that we have identified this link between human food consumption and microbial biodiversity, further research is needed to determine what this means for the health of these animals – and possibly other animals, such as raccoons, martens, deer and hares,” he concludes. . Gillman.

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