Rapidly aging populations and the increasing prevalence of age-related diseases are issues facing many societies. While aging is a complex and not fully understood process, the microbiome and diet are receiving attention as potential ways to support healthy aging.
During a scientific meeting on aging held in Singapore in 2018, experts gathered to discuss the latest knowledge regarding the microbiome and aging and an open-access review summarizing highlights of this meeting, co-authored by Microbiome Insights co-founder Brett Finlay, is now available from EMBO Molecular Medicine.
The review highlights current knowledge on the links between the microbiome and aging. Our microbiome develops in early life in a stepwise manner, diversifying in terms of species and functions in the first several years of life. After this period, it is largely stable but does have the ability to adapt to environmental cues and diet changes while also playing an essential role in digestion and metabolic functions. Drastic alterations to the diversity of the microbiome are associated with disease conditions, highlighting the importance not only of the microbiome but also of potential environmental or dietary interventions too.
The link between microbiome and aging is a promising one because, as the review describes, we lose microbiome diversity as we age. The mechanisms for this aren’t entirely understood but the loss of diversity has been associated with an altered diet and with reduced social interaction, which is a common feature of elderly life in many places. There is also some speculation that the gradual reduced functioning of organs and gut barrier integrity plays a role. Another potential link between aging and the microbiome lies in the cognitive changes and neurodegenerative diseases common to aging. There is some evidence the microbiome is linked to the formation of the blood–brain barrier, myelination, neurogenesis, microglial maturation, and behaviour. Correlations between microbiome changes and neurodegenerative diseases are also known, but this field is still young and reliant mainly on animal studies. More research, especially in humans, is needed before probiotic interventions can be assessed.
Ultimately the question of whether aging can be mitigated is at the heart of this review, and the authors believe there is room for optimism: “Assuming that ageing occurs when the inter‐organ communication fails to maintain homeostasis and not just due to the failure in one step/process, we can envisage new ways to attenuate multiple degenerative pathways in the body.” One of these pathways may be through microbiome and diet interventions. However, they identified several pending issues and lessons to be learned from past aging intervention therapies.
First, the discovery of aging related genes means while aging can be seen from a systemic point of view, it can be coupled with the targeting of specific proteins and genes known to be involved. Strategies aimed at reducing or repairing DNA damage and removing reactive oxygen species following inflammation are also promising. The authors do warn of the many charlatans that have been involved in the anti-aging field that have left many disappointed, and they also place an emphasis on community. Studies have shown that older adults living within the community (as opposed to care facilities) had diets that enhanced the function and diversity of their microbiomes. “These studies elegantly illustrate the perception that ageing does not only need to be managed using physiological interventions.” Rethinking how we care for seniors should then be a priority.
Knowledge gaps and future research identified by the authors include:
- Increase the knowledge of how microbes and microbial metabolites influence signalling pathways and organ function within an aging organism across genders.
- Find “orchestral” microbe leaders that influence microbiome diversity and function via direct or indirect pathways.
- Explore the first tailor-made microbiome intervention study in line with the biology of a given individual.
- Develop a better understanding of the contribution of microbes and their metabolites to organ-to-organ communication, both in early life and during aging.
- Increase knowledge on situations when microbes and the host end up having opposing needs. Can interventions be developed to prevent this? Future experiments involving antimicrobial peptides or phage therapy are therefore of interest.
- Build on existing knowledge: do short-chain fatty acids for increasing barrier integrity come with side-effects?
- Undertake longitudinal studies among older people in order to better understand why the rapidly aging population has an increased prevalence of chronic lifestyle diseases because with an increased lifespan.