Changes in gut fungi and metabolism have been linked to a Western diet.

Changes in gut fungi and metabolism have been linked to a Western diet.
Western diet
According to new research in mice, the typical Western diet can cause obesity-related changes in the gut.
  • In a study of mice, researchers discovered that consuming a highly processed diet high in distilled carbohydrates altered the fungi community in the animals’ guts.
  • These changes in the fungal culture corresponded to changes in how the animals’ bodies processed their food.
  • Future research into the connections between food, gut microbes, and health should include fungi, according to the findings.

The microbes that reside in our guts, referred to as the microbiota, are considered to play a key role in how our bodies metabolize food and many other aspects of our health.

However, the majority of research to date have focused on bacteria, with a few looking at viruses. This suggests that other kingdoms of organisms, such as protists, archaea, and fungi, have been largely overlooked in science.

Recent research in humans and mice suggests that fungi affect the metabolism of their hosts, either directly or indirectly through their effect on bacteria.

Their role, however, is unknown. This is mainly because of the difficulty in differentiating between fungi that are temporary guests — after ingestion in food or from other environmental sources, for example — and those that make their home in the gut.

The University of Tennessee Health Science Center in Memphis researched fungi from laboratory mice of the same genetic backgrounds but from four different suppliers to answer this question.

They gave the mice either a diet high in distilled carbohydrates, which mimicked a highly processed Western diet, or a more balanced, normal lab chow.

The researchers then looked at changes in the abundance and diversity of fungi in the jejunum, a portion of the small intestine. In the intestines of rodents, this is considered to host the most complex fungal populations.

Permanent residents

The gut mycobiome, which is the collective genome of fungi in the gut, differed significantly between mice from various suppliers, which was their first discovery.

The researchers found no proof that the fungi in the food pellets provided by the suppliers and those in the pellets they used in their own experiments were a significant source of the fungi in the animals’ guts when they examined fungi in the food pellets provided by the suppliers and those in the pellets they used in their own experiments.

This clearly indicates that the fungi persisted in their intestines on a long-term basis.

The researchers then found that when the animals ate a refined diet, the diversity of fungi living in their jejunum was decreased when compared to when they ate a regular diet.

This, in fact, was attributed to unhealthy changes in male mice’s metabolisms. The amount of fat stored in their livers, for example, had increased.

Changes in the mycobiome in reaction to a refined diet were also related to higher levels of triglycerides in the blood serum and various hormones involved in metabolism, such as insulin, leptin, and ghrelin.

Leptin assists in the control of body fat, while ghrelin increases appetite.

Increases in these indicators of unhealthy metabolism were linked to an increase in the abundance of the fungal genus Thermomyces and a decrease in the abundance of the genus Saccharomyces.

The researchers’ findings were published in the journal Communications Biology.

Future research implications

The study’s authors summarize their results as follows:

We show that the gut mycobiome of healthy mice is shaped by the environment, including diet, and significantly correlates with metabolic outcomes. We demonstrate that exposure to processed diet leads to persistent differences in fungal communities that significantly associate with differential deposition of body mass in male mice compared [with] mice fed standardized diet.”

Other researchers who study the microbiome and its impact on health often just look at bacteria in fecal samples according to the writers.

They may be missing a significant secret variable that contributes to their findings by ignoring the abundance and variety of fungi in the gut.

The new research had one weakness: it only found associations between diet, fungi, and metabolism, rather than direct causal connections. It’s possible that changes in bacterial communities, for example, are influenced by diet, which can affect metabolism and the mycobiome.