Western diet linked to changes in gut fungi and metabolism
The microbes that are in our guts, or microbiota, are known to play important roles in how our anatomies metabolize the food we consume and many other areas of our health.
To date, however, the majority of studies have centered on bacteria, and few have viewed viruses. This implies that research has largely ignored the other kingdoms of organisms we play host to, such as protists, archaea, and fungi.
Recent research in humans and mice does recommend that fungi influence their hosts’ metabolism, either directly or via their influence on bacteria.
However, their role remains unclear. This is partly because of the issue in distinguishing between fungi that are non permanent guests - after ingestion in food or from other environmental sources, for example - and those that produce their home in the gut.
Researchers at the University of Tennessee Health Science Center in Memphis addressed this question by studying fungi from laboratory mice with the same genetic backgrounds but from four different suppliers.
They fed the mice the diet abundant with purified carbohydrates - which reflects an ultra-processed, Western diet - or a far more balanced, standard lab chow.
The scientists then investigated changes in the abundance and diversity of fungi in part of the small intestine called the jejunum. That is recognized to host the most different fungal populations in the intestines of mice.
Permanent residents
Their first discovery was that the gut mycobiome, which may be the collective genome of fungi in the gut, varied considerably between mice from different suppliers.
However, when the researchers analyzed fungi in the diet pellets supplied by the suppliers and those in the pellets they found in their own experiments, they found no evidence to suggest that these were a major source of the fungi in the animals’ guts.
This strongly suggests that the fungi were everlasting residents in their intestines.
Next, they discovered that whenever the animals ate a processed diet, it reduced the diversity of fungi surviving in their jejunum, weighed against the normal diet.
This, subsequently, correlated with unhealthy changes in the metabolisms of male mice. There were increases in the quantity of fat deposited within their livers, for example.
In addition, changes in the mycobiome in response to a processed diet were associated with increases in serum degrees of triglycerides and different hormones involved in metabolism, including insulin, leptin, and ghrelin.
Leptin helps regulate how much surplus fat, whereas ghrelin boosts appetite.
Specifically, increases in these markers of unhealthy metabolism correlated with an increase of abundance of a fungal genus called Thermomyces and decreased abundance of another genus, called Saccharomyces.
Implications for future research
Summarizing their findings, the study authors write:
“We show that the gut mycobiome of healthy mice is shaped by the surroundings, including diet, and significantly correlates with metabolic outcomes. We demonstrate that exposure to processed diet leads to persistent distinctions in fungal communities that significantly associate with differential deposition of body mass in male mice compared [with] mice fed standardized diet.”
The authors note that other researchers who study the microbiome and its own effects on health often only analyze bacteria in fecal samples.
By ignoring the abundance and diversity of fungi in the gut, they may overlook a crucial hidden variable that plays a part in their results.
One limitation of the brand new study was that it only revealed correlations between diet, fungi, and metabolism, instead of direct, causal links. You will find a opportunity that diet drives changes in bacterial communities, for instance, which can, subsequently, influence metabolism and the mycobiome.
Source: www.medicalnewstoday.com
