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Spd8.0
Spermidine Research
Probably helpsHigh safety
23 peer-reviewed studies
What the evidence says
Probably helps
Spermidine helped in about half (2/4) of the studies that measured an effect — promising, but not unanimous.
Most evidence is from high-quality randomised trials published 2009–2026 with a typical study size of 37 participants.
Based on 23 studies · 13 RCTs · 2,520 total participants
Confidence
High
What the studies found
2helped1unclear1didn't help· 19 more without graded effect data
By outcome
Longevity & agingInduces autophagy; associated with longer lifespan · Ongoing
InflammationMay support heart health through autophagy · Ongoing
Mostly mechanism / observational3 studies
Heart & blood pressure
Too few graded studies2 studies
Immune support
Too few graded studies1 study
Therapeutic & clinical
Too few graded studies1 study
Safety profile
Too few graded studies1 study
By the numbers
Pulled from 19 studies with measurable effects
Likely real effects
50%
across studies
People studied
2,520
typical study: 37 people
Strongest designs
13
0 pooled, 13 randomised
Showed benefit
50%
2/4 studies
How long studies ran
1–3 months
3
3+ months
1
Populations Studied
General population2
Adults2
Older adults with subjective cognitive decline2
Patients with abdominal aortic aneurysm1
Active research area
13 studies in the last 5 years
200920172026
1Gut dysbiosis in abdominal aortic aneurysmSystematic ReviewCited 3×2024
With our expanding knowledge of the downstream pathogenic mechanisms of gut dysbiosis, novel therapeutics such as short-chain fatty acids and spermidine, as well as prognostic biomarkers such as TM...
Chui ESH et al. · Asian journal of surgery (2024)
With our expanding knowledge of the downstream pathogenic mechanisms of gut dysbiosis, novel therapeutics such as short-chain fatty acids and spermidine, as well as prognostic biomarkers such as TMAO have yielded promising preclinical results.
In conclusion, there is strong evidence corroborating the role of gut dysbiosis in the pathogenesis of AAA, wherein its therapeutic and prognostic potential deserves further exploration.
2Intestinal aging and polyamine availabilitySystematic Review2026
In conclusion, modulating the diet-microbiota-polyamine axis represents a promising strategy to promote healthy intestinal aging, meriting deeper mechanistic exploration and validation through clinical studies.
Mafe AN et al. · Nutrients (2026)
It further discusses how age-associated dysbiosis disrupts these interactions and evaluates nutritional and microbial-based strategies such as fermented foods, prebiotics, and probiotics that may enhance polyamine availability and restore gut homeostasis.
From the standpoint of food microbiology and human physiology, this synthesis underscores the translational potential of targeting microbial polyamine production through diet-based interventions.
This article presents a narrative review synthesizing experimental, animal, and emerging human evidence on microbial and dietary polyamines in intestinal aging.
4Colorectal adenomatous polyp riskRCTCited 41×n=1,164 · large study2012
This study showed a role for dietary polyamines in colorectal adenoma risk.
Vargas AJ et al. · The American journal of clinical nutrition (2012)
Large harm
← WorseNo effectBetter →
A dietary intake of polyamines above the median amount in the study population was associated with 39% increased risk of colorectal adenoma at follow-up (adjusted OR: 1.39; 95% CI: 1.06, 1.83) in the pooled sample.
In addition, younger participants (OR: 1.94; 95% CI: 1.23, 3.08), women (OR: 2.43; 95% CI: 1.48, 4.00), and ODC GG genotype carriers (OR: 1.59; 95% CI: 1.00, 2.53) had significantly increased odds of colorectal adenoma if they consumed above-median polyamine amounts.
This study showed a role for dietary polyamines in colorectal adenoma risk.
5Safety and tolerability of spermidine supplementationRCTCited 9×n=37 · small study2024
These findings suggest that hpSPD at 40 mg/day for up to 28 days is safe and well-tolerated in healthy older men.
Keohane P et al. · Nutrition research (New York, N.Y.) (2024)
These findings suggest that hpSPD at 40 mg/day for up to 28 days is safe and well-tolerated in healthy older men.
The study is consistent with preclinical results and provides important evidence supporting the safety of high-purity spermidine supplementation, enabling further research with single-molecule spermidine to investigate its potential biology for improving human health.
This trial was registered at clinicaltrials.gov (NCT05459961).
7Mnemonic discrimination performanceRCTCited 69×n=100 · medium study2022
In this randomized clinical trial, longer-term spermidine supplementation in participants with subjective cognitive decline did not modify memory and biomarkers compared with placebo.
Schwarz C et al. · JAMA network open (2022)
No clear effect
← WorseNo effectBetter →
Could be chance
A total of 100 participants (51 in the spermidine group and 49 in the placebo group) were included in the analysis (mean [SD] age, 69 [5] years; 49 female participants [49%]).
Over 12 months, no significant changes were observed in mnemonic discrimination performance (between-group difference, -0.03; 95% CI, -0.11 to 0.05; P = .47) and secondary outcomes.
In this randomized clinical trial, longer-term spermidine supplementation in participants with subjective cognitive decline did not modify memory and biomarkers compared with placebo.
Intake of the combined supplements showed they were bioavailable and increased in plasma in a dose-dependent manner and provide preliminary data showing enhanced plasma anti-inflammatory and antiox...
Rhodes CH et al. · Nutrition research (New York, N.Y.) (2024)
Intake of the combined supplements showed they were bioavailable and increased in plasma in a dose-dependent manner and provide preliminary data showing enhanced plasma anti-inflammatory and antioxidant functions.
This trial was registered at clinicaltrials.gov (NCT05017428).
9Spermidine levels in blood plasma and salivaRCTCited 26×n=12 · very small study2023
It is rather unlikely that spermidine supplements with doses <15 mg/d exert any short-term effects.
Senekowitsch S et al. · Nutrients (2023)
The plasma metabolome was investigated using nuclear magnetic resonance (NMR) metabolomics. (3) Results: Compared with a placebo, spermidine supplementation significantly increased spermine levels in the plasma, but it did not affect spermidine or putrescine levels.
No effect on salivary polyamine concentrations was observed. (4) Conclusions: This study's results suggest that dietary spermidine is presystemically converted into spermine, which then enters systemic circulation.
Presumably, the in vitro and clinical effects of spermidine are at least in part attributable to its metabolite, spermine.
The results of this study reveal multiple functionalities and immunological pathways affected by PF in humans, identify candidates for the development of fasting mimetic compounds, and uncover targets for investigation in longevity research.
Rhodes CH et al. · The American journal of clinical nutrition (2023)
Furthermore, we found that these metabolites and their combination significantly extended the median lifespan of C. elegans by as much as 96%.
The results of this study reveal multiple functionalities and immunological pathways affected by PF in humans, identify candidates for the development of fasting mimetic compounds, and uncover targets for investigation in longevity research.
11Reactive hyperemia index (RHI)RCTCited 48×n=44 · small study2019
This study suggests that consuming Bifal + Arg YG prevents or reduces the risk of atherosclerosis.
Matsumoto M et al. · Nutrients (2019)
The reactive hyperemia index (RHI), the primary outcome, was measured using endo-peripheral arterial tone (EndoPAT).
The change in RHI from week 0 to 12 in the Bifal + Arg YG group was significantly higher than that in the placebo group, indicating that Bifal + Arg YG intake improved endothelial function.
This study suggests that consuming Bifal + Arg YG prevents or reduces the risk of atherosclerosis.
12Biomarkers of autophagy and cardiometabolic healthRCTCited 1×n=12 · very small study2025
This pilot study found that 3.3 mg/day of spermidine from Miricell® rice germ extract tends to improve biomarkers of autophagy, neuroprotection, and cardiometabolic health.
Bruno G et al. · Alternative therapies in health and medicine (2025)
Noticeable benefit
← WorseNo effectBetter →
Compared to baseline, only the 3.3 mg dose of spermidine from Miricell® increased Beclin-1 by 7.3%, ULK-1 by 13.4%, and BDNF by 12.1%.
Compared to baseline, the same dose resulted in a 20.8% decrease in hs-CRP, a 20.1% decrease in VLDL, and a 26.9% decrease in triglycerides.
This pilot study found that 3.3 mg/day of spermidine from Miricell® rice germ extract tends to improve biomarkers of autophagy, neuroprotection, and cardiometabolic health.
13Cognitive performance improvementRCTCited 47×n=85 · small study2021
By comparison, the group which had a lower spermidine intake showed consistent or declining cognitive performance.
Pekar T et al. · Wiener klinische Wochenschrift (2021)
Noticeable benefit
← WorseNo effectBetter →
Likely real
Blood samples were taken for the determination of spermidine concentration and measurement of metabolic parameters.
The results demonstrated a clear correlation between the intake of spermidine and the improvement in cognitive performance in subjects with mild and moderate dementia in the group treated with the higher spermidine dosage.
The most substantial improvement in test performance was found in the group of subjects with mild dementia with an increase of 2.23 points (p = 0.026) in the mini mental state examination (MMSE) and 1.99 (p = 0.47) in phonematic fluidity.
15Disease progression predictionRCTCited 61×n=38 · small study2018
This proof-of-concept study demonstrates that the metabolomics has a role in evaluating the biological effect of an investigational drug and may be a candidate biomarker as a secondary outcome measure in clinical trials.
Blasco H et al. · PloS one (2018)
To predict SVC from SM C24:1 in group O and SVC from SM OH C22:2 and SM C16:1 in group P+O, we noted a median sensitivity between 67% and 100%, a specificity between 66.7 and 71.4%, a positive predictive value between 66 and 75% and a negative predictive value between 70% and 100% in the test sets.
Changes in metabolomic profiles were closely linked to clinical progression, and correlated with glutamine levels in Group P and amino acids, lipids and spermidine levels in Group O.
Multivariate models accurately predicted disease progression and highlighted the discriminant role of sphingomyelins (SM C22:3, SM C24:1, SM OH C22:2, SM C16:1).
Similarly, no significant effect on the production of proinflammatory cytokines tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and anti-inflammatory interleukin-10 (IL-10) was induced by...
Manzoni MSJ et al. · Food research international (Ottawa, Ont.) (2017)
Similarly, no significant effect on the production of proinflammatory cytokines tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and anti-inflammatory interleukin-10 (IL-10) was induced by the synbiotic or placebo beverages consumption.
The results herein indicate that both the synbiotic and the placebo beverage consumption have increased polyamines levels, which are often reduced in elderly individuals, without influencing inflammatory responses.
In addition, both placebo and synbiotic beverages seems to contribute by maintaining increased polyamines levels.
Chen Y et al. · International journal of rheumatic diseases (2026)
Rheumatoid arthritis (RA) is a chronic autoimmune disease that not only severely impairs joint function but also leads to various systemic complications, significantly reducing patients' quality of life.
This review provided a comprehensive overview of the potential mechanisms of SPD in the pathological progression of RA, including the inhibition of inflammatory cytokines expression, reduction of oxidative stress, modulation of immune cell functions, and maintenance of bone metabolism homeostasis.
Through these mechanisms, SPD shows potential as a promising novel candidate for RA therapy.
19aging and healthspan outcomesSystematic Review2026
This systematic-review examined the effects of Spermidine.
Uemura T et al. · Amino acids (2026)
While animal studies demonstrate clear anti-aging effects of spermidine and spermine, human clinical evidence remains limited, with variable outcomes likely due to bioavailability and metabolic conversion.
Future strategies combining dietary or probiotic polyamine enhancement, enzyme-targeted inhibitors, and personalized metabolic interventions hold promise for extending healthspan.
Collectively, maintaining optimal polyamine homeostasis emerges as a key approach to counteract aging and age-related diseases.
20Autophagy and neuroinflammation in Alzheimer's diseaseSystematic ReviewCited 21×2020
A combination of nutraceutical substances and other preventive measures could have significant clinical impact in a multi-layered therapy approach to counter AD.
Gruendler R et al. · Molecules (Basel, Switzerland) (2020)
Currently, there are no therapy options available that halt AD progression.
The results imply a positive outlook for the reviewed substances to qualify as a novel treatment option for AD.
A combination of nutraceutical substances and other preventive measures could have significant clinical impact in a multi-layered therapy approach to counter AD.