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Supplementation of spermidine at 40 mg/day has minimal effects on circulating polyamines: An exploratory double-blind randomized controlled trial in older men

Keohane P, Everett JR, Pereira R, Cook CM, Blonquist TM, Mah E
Nutrition Research 2024 132:1-14

Bibliography

PubMed
PMID 39405978
DOI
10.1016/j.nutres.2024.09.012
Funding
Trial sponsored by Chrysea Labs; conducted in collaboration with Biofortis Inc. and the University of Greenwich; full disclosure in the original publication.
Competing interests
Some authors are affiliated with Chrysea Labs, the manufacturer of the high-purity spermidine supplement tested (hpSPD); disclosed in the original publication.

Study snapshot

DesignRandomised, double-blind, within-subject, placebo-controlled exploratory trial
ModelHealthy older men (50-70 years)
Sample37 participants
InterventionHigh-purity spermidine trihydrochloride (hpSPD), 40 mg/day, for 7 and 28 days, vs placebo
Duration28 days
EndpointsSafety (clinical, lipid, chemistry, and haematological parameters); Serum and urine polyamine concentrations

What the study showed, in plain terms

This trial gave healthy older men a high-purity spermidine supplement for up to 28 days and found it was safe and well tolerated, but it did not meaningfully raise the amount of spermidine circulating in their blood or urine — the body's own regulation seems to keep levels steady even with supplementation.

Key findings

40 mg/day of high-purity spermidine trihydrochloride was safe and well tolerated over 28 days in older men, with no significant changes in clinical, lipid, chemistry, or haematological safety parameters. Despite the substantial dose, serum and urine polyamine concentrations did not change meaningfully, suggesting effective homeostatic control of circulating spermidine even with supplementation.

What this study can and cannot tell us

Small sample (n=37, men only) and short duration (28 days) limit generalisability. The trial was designed primarily to assess safety, not efficacy, so it cannot speak to whether the modest change in circulating polyamines is enough or insufficient for any downstream health benefit.

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Dr. Khaled Mahmoud, MBBChCritical Care Medicine, Longevity Science & Editorial Direction Dr. Amr Yasser, PhDCardiometabolic, Musculoskeletal, Gut & Bioavailability