Gut dysbiosis, an imbalance in the community of microbes living in your gut, was named the twelfth hallmark of aging in 2023. As the microbiome loses its healthy balance with age, that disruption ripples outward to inflammation, brain health, and beyond, making the gut a genuine frontier in longevity science.
What Is the Gut Microbiome?
Your gut is home to a vast community of bacteria, archaea, and viruses, known together as the gut microbiota. No two people's are identical. Its makeup is shaped by genetics, ethnicity, diet, lifestyle, and environment. Yet despite that individuality, meta-analyses of thousands of people's microbiota have revealed consistent disease associations across populations and countries.
The gut microbiota evolved alongside us in a symbiotic relationship, and it has become an essential part of our biology. It supports nutrient digestion and absorption, defends against pathogens, produces essential metabolites like vitamins, helps maintain the gut lining, and is associated with lower risk of conditions such as obesity and metabolic and cardiovascular disease.
Gut Dysbiosis: The Twelfth Hallmark of Aging
The gut microbiota also communicates with the nervous system and other organs, and it strongly influences whole-body health. When that communication breaks down, through an imbalance in the community, a change in its activity, or a shift in where microbes live, the result is dysbiosis [1]. Dysbiosis contributes to aging and a range of conditions, and as of 2023 it is formally recognized as one of the hallmarks of aging [11].
How the Microbiome Changes With Age
Bacterial diversity in the gut is largely established in childhood and stays relatively stable through adulthood. But the architecture and activity of those bacteria shift gradually with age, eventually reducing diversity.
Large-scale studies reveal something intriguing: individual gut microbiomes become increasingly unique with age. In healthy older people, the microbiome drifts toward this uniqueness, but in less healthy individuals that drift is reduced or absent. Even so, broad trends emerge across many thousands of people. In healthy aging, core bacteria like Bacteroides and Roseburia decline, while others like Bifidobacterium and Akkermansia rise, and these appear to have prolongevity effects [2]. Older adults also tend to carry higher abundances of several health-promoting species [3].
Centenarians and supercentenarians, though, do not always follow the same rules. Their microbiomes show an enrichment of bacteria that generate secondary bile acids, which is thought to help reduce the risk of infection and support intestinal balance. The microbiota also produce other metabolites tied to observable traits: p-cresol correlates with increased frailty [4], while certain indole metabolites correlate with better fitness in older adults and greater health and lifespan in mice, at least partly by reducing inflammatory responses [5].
Fecal Microbiota Transplants
Most health-news followers have heard of fecal microbiota transplants, or FMT. Whether the idea intrigues or unsettles you, FMT has proven to be an effective treatment for C. difficile infection in humans [6], and in animal models it has helped reveal the role the gut microbiota plays in aging and in the health of organs from the brain to the ovaries.
FMT and Aging
Prematurely aged (progeria) mice show intestinal dysbiosis, with more proteobacteria and cyanobacteria and less verrucomicrobia [7], and human progeria patients show dysbiosis too. Long-lived humans show the opposite pattern, with far less proteobacteria and more verrucomicrobia.
When progeria mice received FMT from healthy mice, they gained better health and longer lifespans. Remarkably, administering just one bacterium, the verrucomicrobium Akkermansia muciniphila, produced the same effect. FMT in the other direction, from progeroid to healthy mice, caused harmful metabolic changes, which could be eased by restoring the secondary bile acids and other metabolites of a healthy gut. Together these results suggest that restoring intestinal balance, whether by replenishing bacteria or supplying their metabolites, may be enough to counter premature aging [7].
FMT and the Health of Whole Systems
FMT has also illuminated the gut's role in three areas central to aging. Gut dysbiosis plays a causative role in the chronic systemic inflammation and declining adaptive immunity of aging. Transferring gut microbiota from old mice into young mice triggered an inflammatory response marked by enhanced CD4+ T-cell differentiation, higher inflammatory cytokines, and more circulating bacterial-origin inflammatory factors [8]. In the reverse direction, FMT from young mice into older mice eased age-related changes in the hippocampus and brain immunity and reduced age-associated impairments in cognitive behavior, pointing to the gut's role in maintaining brain health during aging [9]. FMT from young donors also improved ovarian function and fertility in mice, with a healthier immune environment and reduced inflammatory markers in aged ovaries [10]. For more on the inflammation side of this story, see our guide to spermidine and inflammation.
Caloric Restriction and the Gut
Beyond transplants, several prolongevity interventions act on the gut microbiota, and one you can pursue without a prescription or a PhD is caloric restriction. Restricting calories induces structural changes in the gut microbiome and increases bacterial strains like Lactobacillus that are associated with healthy aging.
The Final Hallmark, and Where Spermidine Fits
Gut dysbiosis is the last of the twelve hallmarks set out by Lopez-Otin and colleagues in their 2023 update [11], and its inclusion is no surprise: the causal links between aging and dysbiosis are clear. Interventions aimed at restoring a more youthful microbiome may extend lifespan and support the health of other systems.
Spermidine belongs in this conversation. It is studied for its role in supporting gut health, including the gut barrier and a healthier balance of gut bacteria in animal studies. You can read more about the compound itself in what spermidine is.
Support Your Cellular Renewal With Primeadine
Spermidine drives the cellular renewal that underpins healthy aging, and Primeadine® is how you give your body a consistent daily source of it.
Primeadine Original delivers whole food-derived spermidine from concentrated Japanese wheat germ, and also comes in a powdered format. Primeadine GF offers the same nourishment in a gluten-free formula drawn from Okinawan chlorella. Both are made in Japan and third-party tested batch by batch.
This article is for educational purposes only and is not medical advice. Primeadine® is a food-derived supplement, not a treatment, cure, or preventive for any medical condition. Individual results vary. Consult a qualified healthcare provider before starting any supplement, particularly if you take medication or have a health condition.
References:
1. "What is Dysbiosis?" WebMD, 06 Dec. 2022, www.webmd.com/skin-problems-and-treatments/tc/athletes-foot-topic-overview.
2. "Gut Microbiota and Extreme Longevity" Current Biology, 12 May 2016, multiple authors.
Leave a comment
All comments are moderated before being published.
This site is protected by hCaptcha and the hCaptcha Privacy Policy and Terms of Service apply.