How do typical Western diets disrupt gut health, lead to disease?

Evan Walker
Evan Walker TheMediTary.Com |
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How exactly does a Western diet affect the gut and trigger chronic conditions? Image credit: Joe Raedle/Getty Images.
  • Chronic conditions are on the rise, and frequently involve metabolism and the immune system.
  • The gut microbiome plays a role in both, and potentially plays a causative role in the development of some of these conditions. It is also a potential therapeutic target.
  • The Western diet, though poorly characterized, could play a role in the disruption of the microbiome, but exactly how it may do that is not entirely understood.
  • Researchers have reviewed the evidence around certain dietary patterns and the effect it has on certain bacteria found in the gut, and their roles in specific mechanisms in the human body.

A recent review has highlighted the effect of the Western diet on the microbiome, and the subsequent effect of dysregulation of the microbiome — when the microbial populations in the body become unbalanced — on the risk of developing chronic conditions.

Researchers from Italy published an overview of research into the issue in the journal Best Practice & Research Clinical Gastroenterology, highlighting the effect diet can have on the risk of developing conditions including inflammatory bowel disease (IBD) and Alzheimer’s disease.

In the paper they review the roles of certain bacteria on the gut, and the way certain diets might affect them.

Studies in mouse models have shown that high-saturated-fat and high-sugar diets are associated with lower cognition.

Pre- and probiotics have shown some early potential to improve certain Parkinson’s disease symptoms, and there is some evidence that certain bacterial species occur in lower concentrations in people with Health">major depressive disorder.

However, more robust research is needed to confirm these findings.

The review authors analyzed research surrounding metabolic syndrome and type 2 diabetes with gut dysbiosis.

They propose that the dysregulation of the gut barrier increases inflammation, which can lead to chronic conditions and a tendency to gain fat, which is a key precursor to the development of type 2 diabetes.

While this review does not establish causation, the authors suggest the link between the Western diet and metabolic syndrome can be explained by both the direct impact of the diet’s poor nutrient qualities on systemic inflammation and obesity and also the resulting changes to the gut microbiota from consuming these foods, which indirectly contributes to these health issues.

Hasan Zaki, PhD, associate professor at UT Southwestern Medical School, who studies the molecular mechanisms of inflammatory disorders and was not involved in this research, told Medical News Today that the alteration of the microbiome could be a separate mechanism underpinning the development of some chronic diseases.

“Previously, it was considered that […] [in a] high fat-diet, […] fat and sugar are bad for our Health, because they directly alter our body’s metabolism,“ he noted.

“[This type of diet] helps to increase our cholesterol level in the blood, and ultimately […] is bad for the health because cholesterol leads to heart disease and many other complications. And as a consequence, diabetes, and metabolic disorder [develop]. But there are a lot of studies showing that the diet not only alters metabolism but also it shifts the microbiome composition.”

– Hasan Zaki, PhD

The review was helpful to aid our understanding as while lots of links have been made between the microbiome and certain condition, “but we don’t know exactly what particular bacteria or what particular component or their metabolic products are responsible for,“ Zaki cautioned.

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