The Longevity Series — Guides
What is Spermidine? A Plain-English Guide
Last updated 19 August 2026
The polyamine with the unfortunate name — found in wheat germ, natto and aged cheese, and one of the fastest-rising compounds in longevity research.
What spermidine is
Spermidine is a polyamine — a small molecule produced naturally in the body and found across the food supply. Its concentration in tissues declines with age, which is one reason it has become a major subject of longevity research, with population studies examining dietary spermidine intake and ageing.
Where it's found in food
The richest common sources are wheat germ, natto (fermented soybeans), mushrooms, aged cheese, peas and whole grains. A typical Western diet delivers roughly 10–15mg per day; supplements add a defined amount on top — our Spermidine 10mg Capsules provide 10mg per serving, a high strength for the UK market.
What the human research actually shows
Spermidine's research base comes largely from autophagy work in flies and mice, where it was shown to extend lifespan and protect memory in an autophagy-dependent way.1 The human evidence is newer and more mixed. A small 2018 pilot trial in 30 older adults with subjective cognitive decline found a positive signal on memory performance after spermidine supplementation.2 A larger, longer follow-up randomised controlled trial (the SmartAge study) found that longer-term spermidine supplementation did not significantly improve memory or biomarkers compared with placebo, though it flagged possible effects on verbal memory and inflammation that would need validating at a higher dose in future trials.3
The honest summary: spermidine has strong mechanistic and animal evidence, an established safety profile in the doses studied, and inconsistent results so far in the human cognitive trials that exist. No health claims are authorised for spermidine in the UK.
Wheat-germ extract vs synthesised
Most supplements use wheat-germ extract standardised for spermidine content — check the label states the actual spermidine milligrams, not just the extract weight. A “1000mg wheat germ extract” capsule may contain only 1mg of spermidine. Dose transparency is the single biggest quality signal in this category.
How it fits a longevity stack
Spermidine is commonly run alongside NAD+ precursors — they address different research areas (polyamines vs NAD+ metabolism) and are taken at different points: spermidine is often taken in the evening, NMN in the morning. See the complete NMN guide for the other half of the stack.
Shop NAD+ & longevity supplements →Frequently asked questions
Is spermidine vegan?
Wheat-germ-derived spermidine is plant-based. Check the capsule shell — ours are 100% vegan.
Is spermidine gluten-free?
Wheat-germ extracts may contain traces of gluten. If you are coeliac or gluten-sensitive, check the specific product's allergen statement before buying.
How much spermidine per day?
UK products typically provide 1–10mg daily. Follow your product's label and do not exceed the stated dose.
Who should not take spermidine?
Not suitable for under-18s or for women who are pregnant or breastfeeding. If you take medication or have a medical condition, speak to your doctor before use.
Keep reading
NMN Supplements UK: The Complete Guide · How to build a longevity stack · What is glutathione? · All guides
- Eisenberg T, et al. Induction of autophagy by spermidine promotes longevity. Nat Cell Biol. 2009. Discussed in Madeo F, et al. Spermidine in health and disease. Science. 2018;359(6374).
- Wirth M, et al. The effect of spermidine on memory performance in older adults at risk for dementia: a randomized controlled trial. Cortex. 2018;109:181–188.
- Effects of Spermidine Supplementation on Cognition and Biomarkers in Older Adults With Subjective Cognitive Decline (SmartAge): A Randomized Clinical Trial. JAMA Network Open. 2022;5(5):e2213875. PubMed 35616942
This guide is for general information only and does not constitute medical advice. Spermidine products are food supplements, not medicines — they are not intended to diagnose, treat, cure or prevent any disease.