There has been a host of promising in vivo and in vitro studies published recently on the effect of exogenous polyamines (e.g. putrescine, spermidine and spermine) and spermidine in particular on health outcomes in various model organisms as well as on the biochemical pathways involved in conferring those effects. This is the first high-level study showing lifespan extension in mammals as well as elucidating a likely mechanism in cardiac tissue and establishing a positive correlation between dietary intake of spermidine (assessed through FFQ) and cardiac health in epidemiological cohorts.

Foods rich in spermidine are wheat germ (440 mg/kg), aged cheese (200 mg/kg for 1-year old cheddar), legumes (approx. 100-300 mg/kg for dried soybeans, natto and tempeh and 65 mg/kg for cooked green peas), mushrooms (89 mg/kg), chicken liver (49 mg/kg), broccoli and cauliflower (aprox. 30-40 mg/kg), mango (30mg/kg), celeriac (27 mg/kg) as well as whole grains and potatoes (approx. 10-50 mg/kg).

Sources: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3022763/ - http://en.cnki.com.cn/Article_en/CJFDTOTAL-SHNX200701001.htm - http://www.oryza.co.jp/html/english/pdf/polyamine_vol.2.pdf