Allostatic load and ageing: linking the microbiome and nutrition with age-related health

Ageing is a process of decline in physiological function and capability over time. It is an anticipated major burden on societal health-care costs due to an increasingly aged global population. Accelerated biological ageing is a feature of age-related morbidities, which also appear to share common underpinning features, including low-grade persistent inflammation, phosphate toxicity, diminished Nrf2 activity, a depleted metabolic capability, depressed mitochondrial biogenesis and a low diversity gut microbiome.Social, psychological, lifestyle and nutritional risk factors can all influence the trajectory of age-related health, as part of an individual's exposome, which reflects the interplay between the genome and the environment. This is manifest as allostatic (over)load reflecting the burden of lifestyle/disease at both a physiological and molecular level. In particular, age-related genomic methylation levels and inflammatory status reflect exposome differences. These features may be mediated by changes in microbial diversity. This can drive the generation of pro-inflammatory factors, such as TMAO, implicated in the 'diseasome' of ageing. Additionally, it can be influenced by the 'foodome', via nutritional differences affecting the availability of methyl donors required for maintenance of the epigenome and by the provision of nutritionally derived Nrf2 agonists. Both these factors influence age-related physiological resilience and health. This offers novel insights into possible interventions to improve health span, including a rage of emerging senotherapies and simple modifications of the nutritional and environmental exposome. In essence, the emerging strategy is to treat ageing processes common to the diseasome of ageing itself and thus preempt the development or progression of a range of age-related morbidities.