Gut bacteria extend lifespan via polyamines
Your gut bacteria produce molecules that influence how long you live. New research in fruit flies makes this link specific and measurable for the first time.
Gut bacteria generate dozens of compounds that the body absorbs. Polyamines, such as putrescine and spermidine, are among the most studied. They support cell growth, protein stability, and protection against damage. Earlier studies in mice suggested that higher polyamine levels in the colon could extend lifespan. But was that effect caused by the bacteria themselves, or by confounding factors?
To find out, researchers used gnotobiotic flies: animals raised in a completely sterile environment and then colonized with a single bacterial strain. This allowed the researchers to isolate the bacterial contribution precisely. They compared flies colonized with normal polyamine-producing E. coli to flies colonized with a mutant strain incapable of producing polyamines.
No polyamines, shorter lives
The result was clear. Flies with polyamine-producing bacteria lived significantly longer than those with the mutant strain. Two stress-response genes, TotM and Halo, were also less active in the longer-lived group. Lower activity in these genes suggests a more stable cellular environment under less physiological strain.
The study, published in the journal mBio, is notable because it provides the first direct evidence that polyamines produced specifically by gut bacteria influence host lifespan, not the bacteria as a whole, not diet, but the precise molecules they synthesize.
What does this mean for humans?
Fruit flies are not humans. But the mechanisms involved, including bacterial polyamine production and stress-gene regulation, have also been described in mammals. Spermidine is already found in foods such as wheat germ and aged cheese and is being studied as a supplement. Whether boosting polyamines through diet or gut bacteria actually slows aging in humans has not been established. That question requires dedicated clinical trials. From a longevity perspective, this research is nonetheless compelling: it positions the gut microbiome not merely as a correlate of health but as a mechanistic lever in the aging process.
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