Spermidine

Eisenberg et al. (Nature Medicine, 2016; PMID 27841876): cardioprotection and lifespan extension in MICE. Kiechl et al. (Am J Clin Nutr, 2018; PMID 29955838): higher dietary spermidine associated with lower mortality (observational). Schwarz et al. (JAMA Netw Open, 2022; PMID 35616942): SmartAge, 100 older adults, 12 months, spermidine-rich supplement; no effect on memory or biomarkers. Authors of the mouse study and of SmartAge held equity in the company that makes the supplement tested. D Route 1 for lifespan and mortality. Wirth et al. (Cortex, 2018; PMID 30388439): the 3-month pilot that preceded SmartAge, 30 adults, a moderate within-group memory gain reported by effect size. Memory in older adults with subjective cognitive decline is graded as its own use: tested for a year, no benefit, D on Route 2. Senekowitsch et al. (Nutrients, 2023; PMID 37111071): 12 healthy adults, triple-blind crossover, 15 mg/day for 5 days; plasma spermidine did not change, plasma spermine rose. Keohane et al. (Nutr Res, 2024; PMID 39405978): 37 men aged 50 to 70, 40 mg/day of purified spermidine for up to 28 days; safe, with minimal change in serum and urine polyamines; two authors are employees of the maker of the purified product and the others received its funding. Pekar et al. (Wien Klin Wochenschr, 2021; PMID 33211152): 85 nursing-home residents, higher against lower spermidine intake for 3 months; the abstract reports a 2.2-point MMSE gain in mild dementia and describes no placebo arm, so it does not alter the null. Alsaleh et al. (Aging Cell, 2026; PMID 42169618): 40 adults over 65, 6 mg/day for 13 weeks after a COVID-19 vaccine dose; antibody and B-cell responses improved in vaccine non-responders, immune markers rather than a graded endpoint; part-funded by the wheat germ product's maker, with two authors consulting for it.