The trial used one tablet daily of a compound supplement in which spermidine is one constituent among several. No isolated spermidine dose is established for this purpose.

How long before anything shows?

The trial measured at 90 days, with a pull test also at six months. The hair cycle runs in months: evaluating before three months makes no sense.

Does it work on baldness?

Spermidine does not act on DHT, the driver of androgenetic alopecia. It is therefore not the relevant lever in that case, and the published trial enrolled healthy subjects, not people with established alopecia.

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Spermidine and hair: what the randomised trial actually measured

Published 8/20/2026 · by VEXTA Team

The trial in detail

The human reference is Rinaldi 2017 (Dermatology Practical & Conceptual, DOI 10.5826/dpc.0704a05): a randomised, double-blind, placebo-controlled trial in 100 healthy men and women, one tablet daily for 90 days.

The method is unusually concrete for this product category: at baseline and at the end, 100 hair follicles were plucked and examined microscopically to count those in anagen V–VI, with immunohistochemistry quantifying Ki-67 and c-Kit in the hair bulbs. A pull test was performed at three and six months.

Results: the number of anagen V–VI follicles increased after three months, alongside a rise in Ki-67 (a cell-proliferation marker) and a fall in c-Kit (an apoptosis marker).

What "anagen phase" means

Hair follows a cycle: anagen (active growth), catagen (regression), telogen (rest, then shedding). The proportion of follicles in anagen drives perceived density.

Extending anagen means keeping in growth follicles that would otherwise have moved to rest. The mechanism is real, and it is what the preclinical work predicted: Ramot 2011 (PLoS ONE, DOI 10.1371/journal.pone.0022564) showed in cultured human follicles that spermidine modulates epithelial stem cell function and promotes growth.

The limitations, stated plainly

Three caveats no commercial page mentions:

The tested product is a spermidine-based compound supplement, not isolated spermidine. The effect cannot be attributed to spermidine alone.
One trial. A hundred subjects is reasonable for this field, but an unreplicated result remains unreplicated.
It is not an anti-DHT agent. Spermidine does not act on dihydrotestosterone. For established androgenetic alopecia, it is the wrong lever.

Set this against the pharmacokinetics: oral spermidine does not raise plasma spermidine. A local follicular effect without a measurable blood change remains possible — but that is a hypothesis, not an established mechanism.

How long before judging

Ninety days. That is the trial duration, and it matches hair biology: the follicular cycle runs in months, not weeks. The pull test was repeated at six months.

Judging any hair product at three weeks is meaningless, whatever the product.

Sources

Questions fréquentes

A randomised, double-blind trial in 100 people over 90 days (Rinaldi 2017) measured an increase in anagen V–VI follicles, with Ki-67 up and c-Kit down. The tested product was a spermidine-based compound supplement, and the result has not been replicated.