Share on PinterestNew research in mice suggests that the typical Western diet can lead to changes in the gut caused by obesity. Eduardo Lopez / Addictive Creative / Offset
- A study in mice found that a highly processed diet high in purified carbohydrates changes the community of fungi that live in the animals’ intestines.
- These changes in the fungal community correlated with changes in the way the animals’ bodies metabolized food.
- The study suggests that future research into the links between diet, gut microbes, and health should consider mushrooms.
The microbes that live in our gut or microbiota are known to play an important role in how our bodies metabolize the foods we eat and many other aspects of our health.
So far, however, most studies have focused on bacteria and few have looked at viruses. This means that research has largely ignored the other kingdoms of organisms we live in, such as protists, archaea, and fungi.
Recent research in humans and mice suggests that fungi influence the metabolism of their hosts either directly or through their effect on bacteria.
However, their role remains unclear. This is partly due to the difficulty of distinguishing between mushrooms that are temporary guests – for example, after ingestion in food or from other environmental sources – and those that settle in the intestine.
Researchers at the University of Tennessee’s Health Science Center at Memphis answered this question by studying mushrooms from laboratory mice with the same genetic background but from four different suppliers.
They fed the mice either a diet high in purified carbohydrates – mirroring an ultra-processed Western diet – or a more balanced standard laboratory chow.
The scientists then looked at changes in the abundance and diversity of fungi in a part of the small intestine called the jejunum. This is known to harbor a wide variety of fungal populations in the intestines of mice.
Their first discovery was that the gut mycobioma, which is the collective genome of fungi in the gut, varied dramatically between mice from different suppliers.
However, when the researchers analyzed fungi in the food pellets provided by the suppliers and in the pellets they used in their own experiments, they found no evidence that these were a major source of the fungi in the animals’ gut.
This strongly suggests that the mushrooms were permanent residents of their intestines.
They next discovered that when the animals ate a processed diet, they reduced the variety of fungi living in their jejunum compared to the normal diet.
This, in turn, correlated with unhealthy changes in the metabolism of male mice. For example, the amount of fat that was deposited in their livers increased.
In addition, changes in mycobioma in response to a processed diet have been linked to increases in serum levels of triglycerides and various metabolic hormones, including insulin, leptin, and ghrelin.
Leptin helps regulate the amount of body fat, while ghrelin increases appetite.
In particular, increases in these markers of unhealthy metabolism correlated with an increased frequency of one genus of fungi called Thermomyces and decreased frequencies of another genus called Saccharomyces.
The researchers have published their results in the journal Communications Biology.
In summary, the authors of the study write:
“We show that the intestinal mycobiom of healthy mice is shaped by the environment, including diet, and correlates significantly with metabolic results. We show that exposure to processed food results in persistent differences in fungal communities that are significantly associated with different body mass deposition compared to male mice [with] Mice had a standardized diet. “
The authors note that other researchers studying the microbiome and its effects on health often only analyze bacteria in stool samples.
By ignoring the abundance and variety of fungi in the gut, you may be overlooking an important hidden variable that is contributing to your results.
One limitation of the new study was that it only found correlations between diet, fungi and metabolism and no direct causal relationships. There is a possibility that diet, for example, will induce changes in bacterial communities, which in turn can affect metabolism and mycobioma.
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