Spermidine and Longevity in Humans

Higher Spermidine Intake is linked to Lower Mortality: a Prospective, Population-based Study

A 2018 study published in the American Journal of Clinical Nutrition found that higher dietary intake of spermidine is associated with a lower risk of mortality. This was a prospective, population based study of 829 participants, aged 40-79 years, which looked at 118 item food frequency questionnaires, every five years over a 20 year period (1995-2015). The population cohort was interesting in that included 125 men and 125 women, aged matched in each of the fifth to eighth decades. All participants were from the Bolzano Province of Italy. The primary endpoint of the study was death from any cause. 

The researchers divided spermidine intake into tertiles, with the lowest tertile consuming less than 62.2 umol/d, the second tertile consuming 62.2-79.8 umol/d, and the highest tertile consuming >79.8 umol/d.  Notably, of all 146 nutrients analysed, spermidine exhibited the strongest inverse relation with mortality. In addition to their primary finding, that dietary spermidine intake was associated with lower mortality (equivalent to a 5.7 year difference in chronological age), the researchers also found that spermidine intake was higher in women than men, and that intakes declined with age. As endogenous production of spermidine also declines with age, this suggests an increased need for exogenous spermidine dietary intakes to support healthy ageing. 

Another notable correlation in this study was that those subjects with the highest dietary spermidine intakes had significantly higher glycemic load and higher rates of type 2 diabetes (Kiechl et al., 2018, Table 1, p. 374). While the researchers do not address this point, it may be due to the fact that the main source of dietary spermidine intake in this cohort was whole grains (13.4%), followed by apples and pears (13.3%). Despite the higher rates of diabetes, those in the highest tertile of spermidine intake still had significantly lower mortality rates. Future research is needed to investigate whether increasing dietary intakes from foods that are low glycemic index (e.g., wheat germ, natto, mushrooms) and/or dietary supplements that do not significantly impact blood glucose, may prove to be an advantageous strategy for healthy ageing. 

Reference: Kiechl, S., Pechlaner, R., Willeit, P., Notdurfter, M., Paulweber, B., Willeit, K., ... & Mairhofer, B. (2018). Higher spermidine intake is linked to lower mortality: a prospective population-based study. The American journal of clinical nutrition, 108(2), 371-380.