Last updated: September 26, 2026 · Originally published: June 1, 2026 · By Eternal Elixir Editorial
There is no agreed spermidine dosage. Human trials of spermidine supplements have used 0.9 mg to 1.2 mg a day of wheat-germ spermidine for 3 to 12 months, and higher-dose studies have tested 15 mg a day for 5 days and 40 mg a day for 28 days for safety and blood levels. The one benefit reported, a memory-test improvement in a 30-person pilot, did not hold up in a larger 12-month trial. Our pick is Eternal Elixir Spermidine 10mg, and we say plainly that its 10 mg capsule sits well above the long-term trial doses and inside the range tested for short-term safety.
Quick Answer
Our pick: Eternal Elixir Spermidine 10mg. One capsule a day with a meal gives 10 mg of spermidine, and a 90-capsule bottle costs $49.99, or $0.56 a day, dispatched from Sydney within 24 hours. How that compares with the research: the long-term trials used 0.9 to 1.2 mg a day, a 5-day study used 15 mg, and a 28-day safety study used 40 mg without problems. So 10 mg is roughly eight to eleven times the long-term trial doses and a quarter of the highest dose tested for safety.
Eternal Elixir makes Spermidine 10mg, so this is our recommendation, not a neutral review. This guide is general information, not medical advice.
This spermidine dosage guide for Australia in 2026 covers what each human trial used and found, how our capsule compares, when to take it, how safe higher doses are, and how to read a spermidine label so you know what you are paying for.
Key numbers:
- 0.9 mg a day for 12 months: the longest spermidine trial, in 100 older adults. It found no change in memory against placebo.
- 15 mg a day for 5 days: did not raise spermidine in the blood. Spermine, a related compound, rose instead.
- 40 mg a day for 28 days: the highest dose tested, in 37 men aged 50 to 70, with no safety concerns.
- 10 mg: the spermidine in each Eternal Elixir capsule.
What is the right spermidine dosage?
Spermidine is a polyamine found in food and made in the body. Interest in it as a supplement comes mostly from animal studies, and the human trials so far are small. There is no official recommended intake, so the sensible way to think about dose is to line up what trials used, what they found, and what products sell.
Most trials used a spermidine-rich extract of wheat germ. A newer study used high-purity spermidine trihydrochloride. Diet also supplies spermidine, and an observational study of 829 adults found that people who ate more of it had lower death rates over 20 years. That kind of study cannot show that spermidine caused the difference. Our guide to foods high in spermidine in Australia covers the richest sources.
How much spermidine per day? What the research shows
| Daily dose | Trial | People and length | What it found |
|---|---|---|---|
| 0.9 mg (wheat-germ extract) | Schwarz 2022, SmartAge | 100 adults aged 60 to 90, 12 months | No change in memory or secondary measures against placebo. Adverse events balanced between groups |
| 1.2 mg (wheat-germ extract) | Schwarz 2018 and Wirth 2018 | 30 adults aged 60 to 80, 3 months | No safety differences from placebo. A memory test improved with a medium effect size in this pilot |
| 15 mg | Senekowitsch 2023 | 12 healthy adults, two 5-day phases | Blood spermidine unchanged. Blood spermine rose |
| 40 mg (high-purity) | Keohane 2024 | 37 healthy men aged 50 to 70, up to 28 days | No changes in safety blood tests. Little change in blood polyamines |
Three things follow from the table. First, the only trials that ran for months used about 1 mg a day, and the larger, longer one found no memory benefit. Its authors suggested future studies test higher doses. Second, the pharmacokinetic study found that even 15 mg a day did not raise spermidine in the blood over 5 days, because it appears to be converted to spermine before it reaches the circulation. Its authors wrote that doses under 15 mg a day are unlikely to have short-term effects. Third, 40 mg a day for 28 days caused no safety problems in healthy older men.
Where our 10 mg capsule sits
Eternal Elixir Spermidine 10mg gives 10 mg of spermidine per capsule, one capsule a day with a meal. That is about eight times the 1.2 mg pilot dose and eleven times the 0.9 mg SmartAge dose. It is two-thirds of the 15 mg pharmacokinetic dose and a quarter of the 40 mg safety dose. None of the trials in this guide tested 10 mg a day over months, and no benefit has yet been confirmed at any dose, so we cannot point to evidence that 10 mg does something 1 mg does not. What the evidence does support is that doses up to 40 mg have been well tolerated in the short term.
Add Spermidine 10mg to cart · $49.99
Spermidine dosage by goal
- Memory and brain ageing. The only relevant human trials used 0.9 to 1.2 mg a day of wheat-germ spermidine. The 3-month pilot found a memory-test improvement, and the 12-month trial did not. The SmartAge authors noted possible effects on verbal memory in exploratory analyses that need confirming at higher doses.
- Autophagy and cellular ageing. Spermidine is described as an autophagy-inducing agent from cell and animal work. The human trials in this guide did not measure autophagy, so there is no human dose for it.
- General healthy ageing. The observational data links higher dietary intake with better survival, but it cannot give a supplement dose.
If your interest is autophagy in general, our overview of autophagy supplements in Australia covers where spermidine fits, and our Ca-AKG vs spermidine comparison sets it against another popular option.
Best time to take spermidine
No trial has compared times of day. Our label says one capsule daily with a meal. Taking it with the same meal each day makes it easier to remember, which matters because every trial used daily dosing.
Many people take spermidine with other longevity supplements. Our guides to taking spermidine and NMN together and how spermidine compares with NMN cover the common pairing. If you want all three of NMN, spermidine and pterostilbene, our Cellular Longevity Stack already includes Spermidine 10mg, so do not buy the two together. For single products, see NMN 500mg and Ca-AKG 500mg, and our longevity stack guide for how people combine them.
Spermidine dosage safety: is more better?
Across the trials in this guide, from 0.9 mg a day for 12 months to 40 mg a day for 28 days, researchers reported no safety differences from placebo. The 40 mg study also found little change in blood polyamines, which its authors read as the body keeping tight control of polyamine levels.
That tight control is also why more is not clearly better. The 15 mg study did not raise blood spermidine, and the 40 mg study barely moved it. The trials in this guide give no long-term safety data above about 1 mg a day. Speak to your doctor or pharmacist before starting if you are pregnant or breastfeeding, take prescription medicines, or have a health condition.
How to choose a spermidine supplement in Australia
The number that matters is milligrams of spermidine per serve, not the weight of the extract it comes in. A wheat-germ product can deliver around 1 mg of spermidine however much extract the label lists, as the SmartAge supplement did at 0.9 mg a day. Then work out the cost per day and the cost per milligram. Prices as of Sep 2026, from each brand’s own page.
| Product | Price (AUD) | Spermidine per capsule | Capsules per bottle | Cost per day (1 capsule) | Cost per 10 mg | Buy |
|---|---|---|---|---|---|---|
| Eternal Elixir Spermidine 10mg (our pick) | $49.99 | 10 mg | 90 | $0.56 | $0.56 | View Spermidine 10mg |
| Naturecan Spermidine, 180 capsules | $100.00 | 5 mg | 180 | $0.56 | $1.11 | Naturecan |
| Naturecan Spermidine, 60 capsules | $40.00 | 5 mg | 60 | $0.67 | $1.33 | Naturecan |
Eternal Elixir makes Spermidine 10mg and lists it first. Naturecan’s 5 mg capsule is the closer match to the lower doses if that is what you want, and its 180-capsule pack costs the same per day as ours. Per milligram of spermidine, ours costs half as much. Naturecan’s page recommends one capsule a day and says free shipping starts at $179. Our Spermidine 10mg ships from Sydney within 24 hours, with a 30-day money-back guarantee, Afterpay, and free shipping over $100. For more brands, see our comparison of the best spermidine supplements in Australia, and for formats, our spermidine powder vs capsules guide.
Frequently asked questions
How much spermidine should I take per day?
There is no official amount. The long-term trials used 0.9 to 1.2 mg a day, and short-term studies found 15 mg and 40 mg a day well tolerated. Most supplements sit between those points: our capsule gives 10 mg, and Naturecan’s gives 5 mg. Follow your product’s label and ask your doctor if you are unsure.
What is the best spermidine supplement in Australia?
Our pick is Eternal Elixir Spermidine 10mg: 10 mg per capsule, 90 capsules for $49.99, or $0.56 a day, dispatched from Sydney. It costs half as much per milligram as Naturecan’s 5 mg capsules. Keep in mind that no benefit has been confirmed at any dose, and that 10 mg is well above the long-term trial doses.
Add Spermidine 10mg to cart · $49.99
What is the best time to take spermidine?
No trial has compared times of day. Our label says one capsule daily with a meal, and taking it with the same meal each day helps you stay consistent.
Can you take too much spermidine?
The highest dose tested, 40 mg a day for 28 days, caused no safety problems in healthy men aged 50 to 70. In these trials, longer-term data only covers about 1 mg a day. The body appears to regulate polyamine levels closely, so high doses are unlikely to add much. Check with your doctor if you are pregnant, breastfeeding, on medication or managing a health condition.
How long does spermidine take to work?
There is no clear timeline because no benefit has been confirmed. The 3-month pilot at 1.2 mg reported a memory-test improvement, and the 12-month trial at 0.9 mg found none. If you try it, give it at least three months of daily use, which is one bottle of our capsules.
The bottom line
Spermidine has no agreed dose, and the best human trials used about 1 mg a day without showing a clear benefit. Short-term studies suggest doses up to 40 mg a day are well tolerated. Our Spermidine 10mg gives 10 mg a capsule for $0.56 a day, above the long-term trial doses and inside the tested safety range, and we would rather you know that before you buy. You can also browse the full Eternal Elixir range.
Sources
- Schwarz C, Benson GS, Horn N, et al. Effects of spermidine supplementation on cognition and biomarkers in older adults with subjective cognitive decline: a randomized clinical trial. JAMA Network Open. 2022;5(5):e2213875. PubMed 35616942
- Schwarz C, Stekovic S, Wirth M, et al. Safety and tolerability of spermidine supplementation in mice and older adults with subjective cognitive decline. Aging (Albany NY). 2018;10(1):19-33. PubMed 29315079
- Wirth M, Benson G, Schwarz C, 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. PubMed 30388439
- Senekowitsch S, Wietkamp E, Grimm M, et al. High-dose spermidine supplementation does not increase spermidine levels in blood plasma and saliva of healthy adults: a randomized placebo-controlled pharmacokinetic and metabolomic study. Nutrients. 2023;15(8):1852. PubMed 37111071
- Keohane P, Everett JR, Pereira R, et al. Supplementation of spermidine at 40 mg/day has minimal effects on circulating polyamines: an exploratory double-blind randomized controlled trial in older men. Nutrition Research. 2024;132:1-14. PubMed 39405978
- Kiechl S, Pechlaner R, Willeit P, et al. Higher spermidine intake is linked to lower mortality: a prospective population-based study. American Journal of Clinical Nutrition. 2018;108(2):371-380. PubMed 29955838
- Naturecan Spermidine Supplement product page, checked 26 September 2026. naturecan.com.au
