Kibe · Scientific reports 2014 · Controlled animal experiment · n=?

Upregulation of colonic luminal polyamines produced by intestinal microbiota delays senescence in mice.

Cited 285 times in the scientific literature.

Level 5 - mechanism / opinion, no new human data

Animal experiment with no human data (Oxford CEBM Level 5).

PubMed 24686447 · doi:10.1038/srep04548 · record verified 2026-08-30

What was done

Mice were orally administered arginine alone or in long-term combination with the probiotic bacterium *Bifidobacterium* strain LKM512 to evaluate effects on colonic and circulating polyamine concentrations (putrescine, spermidine, spermine), inflammation, longevity, and age-induced memory impairment.

What was found

Arginine intake increased putrescine concentrations in the colon and elevated spermidine and spermine levels in the blood. Combined long-term administration of arginine and LKM512 suppressed inflammation, improved longevity, and protected mice against age-induced memory impairment. The abstract reports no numerical values, effect sizes, or statistical metrics.

Why it matters

This study demonstrates that microbial upregulation of luminal polyamines via combined probiotic and substrate supplementation can mitigate systemic aging phenotypes and cognitive decline in a mammalian model.

Limits

The study is restricted to mice and provides no human clinical data. The abstract omits sample sizes, control group specifications, exact dosages, treatment duration, and quantitative data for all outcome measures.

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