Guido Kroemer, Simon Sedej, Frank Madeo and colleagues now show that consistent administration of spermidine in the drinking water of mice extends their median lifespan, even when spermidine supplementation is not started until the mice are middle-aged. Spermidine improved heart function in older mice, suggesting that a delay in the ageing of the heart contributes to the increase in lifespan. Spermidine’s cardioprotective effects were due to its ability to activate autophagy, given that mice with a genetic defect in autophagy did not benefit from spermidine administration. Spermidine also induced cardioprotective effects in rats by lowering their blood pressure and improving their heart function.
The authors also tested whether intake of dietary spermidine could be beneficial for humans. According to the results of a questionnaire in which a group of approximately 800 people (in the town of Bruneck, Italy) reported how often they ate different foods, higher intake of spermidine was associated with a lower risk of heart failure and other cardiovascular diseases, particularly in men, and lower blood pressure.
On the basis of these findings, the authors suggest that more rigorous clinical studies be conducted to test the therapeutic benefits of dietary spermidine.