LONGEVITY LATEST

Deep Dive — Issue 06 Companion

By Christian Thomsen, Editor

(And Why Yours Doesn’t Have to Be Different)

TL;DR: Centenarians worldwide share a surprisingly consistent gut microbiome signature — one that resembles young adults more than their elderly peers. Key features: high Bifidobacterium and Akkermansia muciniphila, robust SCFA production, low pathobiont abundance. Faecal transplant experiments in mice suggest this isn’t just correlation. You can shift your microbiome toward these signatures through dietary fibre, fermented foods, and exercise. No exotic intervention required.

I expected the centenarians’ guts to look old. Depleted. Maybe a bit resilient, but fundamentally worn down — the way most things look after a century of use. That’s not what the data showed.

In 2023, Pang et al. sequenced the gut microbiomes of 1,575 people in Guangxi, China — 297 of them centenarians aged 100 to 117 (Nature Aging, PMID: 37117794). The centenarians’ microbiomes didn’t look like those of elderly people. They looked like those of twenty-year-olds. Youth-associated signatures across multiple metrics: a Bacteroides-dominated enterotype, higher species evenness, enrichment of beneficial Bacteroidetes, depletion of the opportunistic pathobionts that normally pile up with age. Their bacterial communities had more in common with people seventy years younger than with people ten years younger.

That alone would be a striking finding. But there’s a detail that elevates it from interesting to genuinely important.

The researchers followed 45 of these centenarians longitudinally over 18 months. In those who remained healthy, the youth-associated signatures didn’t just hold steady — they got stronger. The microbiome was becoming more youthful with age. In centenarians whose health declined, the signatures weakened. The gut wasn’t just reflecting health status. It seemed to be tracking it in real time — possibly even driving it.

A caveat worth noting: birth records in rural Guangxi before 1949 are unverifiable, so the exact ages of the oldest participants carry some uncertainty. The biological findings, however, are internally consistent and have been replicated elsewhere.

If this were just one cohort from one province in southern China, I’d note it and move on. But the Guangxi findings sit within a pattern that keeps showing up wherever researchers look.

Italian centenarian studies, starting with the pioneering work of Elena Biagi (Current Biology, 2016, PMID: 27185560), found that semi-supercentenarians (105–109 years old) harboured elevated Akkermansia, Bifidobacterium, and Christensenellaceae — a family consistently linked to leanness and reduced inflammation. Sardinian centenarian studies found higher metabolic diversity and more SCFA production genes. Japanese cohort data (n=1,596) showed age-related Blautia decline was less pronounced in long-lived individuals. A 2025 synthesis in the Journal of Biomedical Science confirmed the hallmarks across populations.

I’ve spent a lot of time with these papers now, and three features come up again and again:

Bifidobacterium persistence. Most people lose roughly 99% of their Bifidobacterium between infancy and old age. Centenarians haven’t. This matters because Bifidobacterium produces acetate — a short-chain fatty acid that strengthens the gut barrier and modulates immune function. Its decline is one of the most consistent features of normal ageing.

Akkermansia muciniphila abundance. This mucin-degrading bacterium maintains the gut’s protective mucus layer. It’s positively associated with healthy metabolic markers and inversely associated with obesity, type 2 diabetes, and inflammation. Centenarians consistently show elevated levels.

Low pathobiont load. Ageing normally brings an increase in Proteobacteria and LPS-producing species — the bacteria that fuel the chronic inflammation we explored in last week’s inflammageing Deep Dive (Issue 05). Centenarians show significantly lower levels of these pro-inflammatory species, which may partly explain how they avoid the inflammageing spiral.

This is the question that keeps the field honest — and it’s the one I get asked most when I write about microbiome research. Does a youthful gut help you live longer? Or does being healthy enough to reach 100 simply allow you to keep a youthful gut?

The honest answer is: we don’t know for certain in humans. But the animal evidence has been piling up, and it points strongly in one direction.

Bárcena et al. (2019, Nature Medicine) performed faecal microbiota transplants from wild-type mice into progeroid mice — animals genetically programmed to age rapidly. FMT extended both lifespan and healthspan. Here’s the part that stopped me: transplantation with Akkermansia muciniphila alone was sufficient to reproduce the benefit. One species. That’s a level of specificity you almost never see in microbiome research.

A separate study (Boehme et al., 2021, Nature Aging) went further. FMT from young mice into aged mice reversed cognitive impairment — the aged recipients’ brains functioned more like young brains after receiving young gut bacteria. If someone told me that as a headline, I’d be sceptical. But the methodology is solid, and the effect was measurable.

In killifish — the shortest-lived vertebrate — FMT from young to old fish extended lifespan and delayed behavioural decline (Smith et al., 2017, eLife).

None of this proves causation in humans. But the direction of evidence is consistent: shift the gut toward a youthful profile, and health outcomes improve. The microbiome isn’t just a bystander in ageing. It’s a player.

If centenarian microbiomes are characterised by high Bifidobacterium, high Akkermansia, robust SCFA production, and low pathobionts, the practical question is: can you move your microbiome in that direction? The evidence says yes.

Dietary fibre (Issue 06, Grade A) is the single most reliable lever. SCFAs are produced by bacterial fermentation of fibre — no fibre, no fuel. The systematic review we cited in this week’s newsletter (Badal et al., 2020, 27 studies) found that longevity-associated microbiome stability depends on SCFA-producing bacteria. Thirty grams daily is the minimum target; most Britons eat 18g. The gap is embarrassingly easy to close — legumes, whole grains, nuts, and vegetables. It’s the least glamorous intervention in this article, and probably the most important.

Fermented foods (Issue 06, Grade B+) increase microbial diversity and reduce inflammatory markers. The Stanford FeFiFo trial (Sonnenburg, Gardner et al., Cell, 2021) showed measurable improvements within ten weeks. Diversity is one of the hallmarks of centenarian microbiomes.

Probiotics (Issue 06, Grade B) selectively boost Bifidobacterium and Lactobacillus — two centenarian signature genera. The 2025 meta-analysis (Li et al., 29 RCTs, n=1,633) confirmed this effect in older adults specifically.

Exercise improves gut microbiome diversity independently of diet. It also reduces systemic inflammation (Issue 05 inflammageing Deep Dive) and supports mitochondrial health (Issue 04). I’d argue exercise is the single intervention that touches every aspect of gut-longevity biology simultaneously.

Berberine (Issue 06 Spotlight) specifically increases Akkermansia muciniphila — one of the centenarian signature species. The 6-year CBAR-FE data suggests its effects persist long after cessation, which is potentially significant for microbiome remodelling.

The centenarian microbiome research doesn’t tell us that a specific bacterial profile will make you live to 100. Genetics, environment, diet, and social factors all contribute — and we can’t yet disentangle the microbiome’s independent contribution from everything else. I’ve read enough of these studies to know that the causal picture is genuinely uncertain.

But the research does tell us something actionable: the bacterial communities associated with extreme longevity are not mysterious or inaccessible. They’re characterised by organisms that thrive on fibre, fermented foods, and physical activity — interventions available to everyone.

If I were designing a gut-optimisation protocol from this evidence, it would be boringly simple: 30g+ of fibre from diverse plant sources daily (a tin of lentils, two portions of vegetables, and a handful of oats gets you most of the way there), two to four servings of genuinely fermented foods, regular exercise, and targeted probiotics if you want to specifically boost Bifidobacterium. That’s not a supplement stack — it’s a shopping list.

The most expensive intervention in that protocol is the kefir.

Stay curious and stay healthy!

— Christian Thomsen, Editor

1.    Pang S, et al. Longevity of centenarians is reflected by the gut microbiome with youth-associated signatures. Nat Aging. 2023;3(4):436-449. PMID: 37117794

2.    Biagi E, et al. Gut microbiota and extreme longevity. Curr Biol. 2016;26(11):1480-1485. PMID: 27185560

3.    Badal VD, et al. The gut microbiome, aging, and longevity: a systematic review. Nutrients. 2020;12(12):3759. PMID: 33297486

4.    Bárcena C, et al. Healthspan and lifespan extension by fecal microbiota transplantation into progeroid mice. Nat Med. 2019;25:1234-1242. PMID: 31332389

5.    Boehme M, et al. Microbiota from young mice counteracts selective age-associated behavioral deficits. Nat Aging. 2021;1:666-676. PMID: 37117767

6.    Smith P, et al. Regulation of life span by the gut microbiota in the short-lived African turquoise killifish. eLife. 2017;6:e27014. PMID: 28826469

7.    Sonnenburg JL, Gardner CD, et al. Gut-microbiota-targeted diets modulate human immune status. Cell. 2021;184(16):4137-4153. PMID: 34256014

8.    Li et al. Effects of probiotics, prebiotics, and synbiotics on gut microbiota in older adults. Nutr J. 2025;24:147.

9.    From dysbiosis to longevity: the gut microbiome’s impact on aging. J Biomed Sci. 2025;32:93.

This article is part of Longevity Latest’s Deep Dive series — long-form explorations of the biological mechanisms that drive ageing.

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