Gamma-linolenic acid (GLA) is an omega-6 fatty acid that is most commonly found in the seeds of the evening primrose plant. You can find this ingredient in some topical treatments marketed toward hair loss.
- The in vitro (in cells) evidence suggests that GLA may inhibit 5α-reductase, a key enzyme in the conversion of testosterone to dihydrotestosterone. This was subsequently confirmed by a study looking in vivo at hamsters that had been induced to grow ‘flank organ growths’ which are known to be androgen dependent. After topical treatment with GLA, the growths shrank down indicating that GLA had an inhibitory effect on androgen activity. This may be beneficial for people with androgenetic alopecia, however, there don’t appear to be any studies to confirm this.