Spermidine has been noted to boost autophagy and promote greater longevity to some degree in laboratory animals. Its activities are in the process of being advanced by some researchers as candidate drug mechanisms for slowing aging. Given that, it makes sense for researchers to investigate spermidine levels in longer lived individuals to see if there is any association:
Polyamines (putrescine, spermidine and spermine) are a family of molecules deriving from ornithine, through a decarboxylation process. They are essential for cell growth and proliferation, stabilization of negative charges of DNA, RNA transcription, translation and apoptosis.
Recently, it has been demonstrated that exogenously administered spermidine promotes longevity in yeasts, flies, worms and human cultured immune cells. Here, using a cross-sectional observational study, we determined whole-blood polyamines levels from 78 sex-matched unrelated individuals divided into three age groups: group 1 (31-56 years, N=26, mean age: 44.6±6.07), group 2 (60-80 years, N=26, mean age: 68.7±6.07) and group 3 (90-106 years, N=26, mean age: 96.5±4.59).
Polyamines total content is significantly lower in group 2 and 3 compared to group 1. Interestingly, this reduction is mainly attributable to the lower putrescine content. Group 2 displays the lowest levels of spermidine and spermine. On the other hand, [nonagenarians and] centenarians (group 3) display significant higher median relative percentage content of spermine with respect to total polyamines, compared to the other groups.
For the first time we report polyamines profiles from whole blood of healthy [nonagenarians and] centenarians, and our results confirm and extend previous findings on the role of polyamines in determining human longevity. However, although we found an important correlation between polyamines levels and age groups, further studies are warranted to fully understand the role of polyamines in determining life-span. Also, longitudinal and nutritional studies might suggest potential therapeutic approaches to sustain healthy aging and to increase human life-span.