The Conversation: age-related changes in the gut microbiome reduce immunity

Age-related changes in the composition and diversity of microorganisms in the gut and the resulting inflammation leads to reduced immune responses and an "ageing" immune system. Narvin Jandu, a biology professor at the University of Waterloo, Canada, told The Conversation.

Jandu explained that the gut microbiome is the collection of microorganisms living in the gastrointestinal tract. The microbiome contributes to the maintenance of a stable internal environment in the body when faced with external changes. This phenomenon is known as homeostasis. The intestinal microbiome maintains homeostasis in various ways, such as tonifying the immune system and breaking down dietary fibre to short-chain fatty acids to strengthen the intestinal walls.

Normally, the gut microbiome and the immune system work in close co-operation. Microorganisms in the gut send signals that are detected by immune sensors. This allows the immune system to regulate the amount of beneficial bacteria in the gut, helping to maintain immune homeostasis. Through this interaction, the adaptive immune system also receives stimuli from harmful substances called antigens that trigger an immune response.

However, as we age, the composition and balance of microorganisms in the gut change. This leads to microbial dysbiosis, which means a decrease in the number of beneficial bacteria in the gut along with an increase in the number of inflammatory bacteria. Inflammation causes the immune system to malfunction and makes a person vulnerable to various diseases.

Apart from the imbalance of microorganisms in the gut, several factors support inflammation and impaired immune function. These include psychological stress, hypodynamia, poor diet and chronic infections.

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