The
gut microbiome refers to a dynamic population of microorganisms which exert a marked influence on the health and wellbeing of the host (Thursby & Juge 2017). When the composition of microorganisms is out of balance, this is referred to as
dysbiosis.
Gut dysbiosis is a significant pathophysiology that contributes to overall cellular ageing and is implicated in a number of human diseases, including neurodegenerative, cardiovascular, metabolic and gastrointestinal diseases (Chen et al. 2021).
Many factors significantly impact the microbiome composition, either promoting or preventing gut dysbiosis, and thus, by extension, cellular ageing. One of the primary factors is diet (Vijay & Valdes 2022).
A
Western-style diet high in animal protein, saturated fats and refined carbohydrates is associated with gut dysbiosis (Singh et al. 2017).
This dietary pattern causes an increase in opportunistic microorganisms that trigger inflammation, a key factor in cellular ageing. Moreover, these pathogenic microorganisms that arise from high intakes of dairy, eggs and meat cause an increase in the compound Trimethylamine N-Oxide (TMAO), which is a powerful pro-inflammatory and pro-atherogenic agent.
This same dietary pattern also elevates the inflammatory marker C-reactive protein (Singh et al. 2017).
Conversely, a
dietary pattern centred upon plants with high quantities of
'microbiota accessible carbohydrates' (MACs), such as oligosaccharides, resistant starches and pectins, promotes a
healthy microbiome and thus
downregulates this dysbiosis-ageing pathway (Singh et al. 2017).
When beneficial gut microorganisms ferment these MACs, they produce Short-Chain Fatty Acids (SCFAs), like butyrate and propionate, as a by-product.
SCFAs are a major energy source for intestinal epithelial cells and strengthen the mucosal barrier (Singh et al. 2017). These SCFAs also reduce inflammation and cellular ageing (Vijay & Valdes 2022).
Beneficial metabolites produced by gut microorganisms can protect against
soft tissue changes and signs of ageing, like decreased collagen production, epidermal thinning and loss of subcutaneous fat. These changes often lead to fine lines, wrinkles and skin dryness.
The skin itself has its own population of microorganisms that help maintain skin barrier integrity when balanced, providing protection against conditions such as eczema, psoriasis and rosacea.
Adopting a
plant-based diet rich in fruits and vegetables also increases other beneficial plant components besides MACs, such as
polyphenols (including anthocyanins, quercetin and catechins).
A reciprocal relationship exists between these polyphenols and the gut microbiome: beneficial microorganisms increase the bioavailability of polyphenols, and these polyphenols in turn reduce pro-inflammatory markers like C-reactive protein and plasma triacylglycerol.
Through the presence of
microbiota accessible carbohydrates and various
polyphenols, a plant-based diet rich in fruits and vegetables helps to
promote a healthy gut microbiome and
mitigate gut dysbiosis.
In doing so, it causes a marked decrease in inflammation, toxin production and premature cellular ageing.
