KEY POINTS

Spermidine is a naturally occurring polyamine.

Widely encountered in ribosomes and living tissues.

Created from its precursor putrescine.

Two pathways in which putrescine is created, both start with the amino acid arginine.

Polyamines such as spermidine and putrescine are known to promote autophagy.

Spermidine plays an important role in the regulation of various biological processes, including levels of intracellular pH and the maintenance of cell membrane potential. 

Key morphogenetic determinant for the life span of cells.

Lack of spermidine is highly correlated with reduced life spans, chronic stress, and acute inflammation.

Some evidence that the age-related decline of spermidine supports the onset of age-related diseases