Longevity Supplement Research Library
Primary human studies and evidence reviews used to keep our buyer guides attached to science rather than floating off into longevity mythology.
Spermidine & Autophagy
Human spermidine research is still developing. A 2022 randomized trial in older adults with subjective cognitive decline did not support turning spermidine into a broad cognitive-treatment claim, while a 2025 pilot study of 3.3 mg/day spermidine-rich rice germ extract reported exploratory changes in autophagy-related and cardiometabolic biomarkers. Mechanism is interesting; certainty is not the same thing.
NAD+ & NMN
NMN is a precursor in NAD+ metabolism. Human randomized trials have shown that oral NMN can raise blood NAD-related measures, but effects on clinical outcomes are mixed and study-specific. A 2024 review of randomized trials found the metabolic-benefit picture remained uncertain, which is a useful antidote to labels that behave as if NAD+ biology already settled every longevity question.
Resveratrol & Quercetin
Resveratrol and quercetin are polyphenols with substantial preclinical and human research, but outcomes vary by dose, population and endpoint. A 2025 meta-analysis found no significant overall effect of resveratrol supplementation on human SIRT1 in the pooled analysis, while human quercetin studies show that bioavailability differs substantially across formulations.
Longevity Stacks
A longevity stack combines ingredients with different biological rationales. That can make a formula coherent, but separate ingredient studies do not prove the finished combination is clinically synergistic. The more complicated the stack, the more important transparent doses and finished-product evidence become.