Spermidine is essential to the cellular cleaning mechanism (autophagy) and may prevent hair loss and extend human lifespan.

noli's read

Spermidine does indeed stimulate autophagy, a vital cellular recycling process, as demonstrated in numerous studies on animal models and cell cultures (Source: Cell, mechanistic study). It is accurate that it has shown effects on longevity in non-human models (yeast, flies, mice), but extrapolating these results directly to humans is a major oversimplification (Source: Nature Medicine, mouse study). Regarding hair loss, preliminary studies suggest stimulation of hair growth in vitro, but robust clinical evidence in humans remains very limited (Source: PLoS ONE, observational/in vitro study). The idea that spermidine extends life in all tested species is therefore a shortcut: while associations are observed in human epidemiological studies, the causal link remains difficult to establish. To date, there is no scientific consensus confirming spermidine as a universal longevity elixir for humans.

the sources

No named source held this one up — that absence is part of the verdict.