Sphinganine is a chemical that can be made dehydrosphingosine, when it’s reduced using NADPH. It’s been shown to block the enzyme 5-alpha reductase (5AR). 5AR is the enzyme that converts testosterone into dihydrotestosterone (DHT). DHT is the androgen hormone that binds with androgen receptors in the hair follicles. When it does this in the body hair and facial hair it makes the small vellus hairs grow, thicken and darken into terminal hairs. However, in the scalp it seems to have the opposite effect in some men, causing hair follicles to miniaturize.
The process by which DHT causes hair follicle miniaturization is still not conclusively understood. However it’s likely to do with inflammation, as I explained in my article “Why does DHT cause hair loss?“
Here’s an abstract from the study on Sphinganine’s effect on 5AR and inflammation:
Sphingolipids are well known to promote keratinocyte differentiation and to induce ceramide production. In addition, they show anti-inflammatory and antimicrobial activities. Thus, the aim of this study is to investigate the potential effect of sphinganine on prolonging the hair anagen rate and improving the overall hair quality and scalp health. The inhibitory potential of sphinganine toward 5-α-reductase was studied using an in vitro assay. The stimulation of the antimicrobial peptide HBD2 by sphinganine was measured by real-time polymerase chain reaction and immunostaining. Sphinganine bioavailability was studied ex vivo using a pig skin model. A placebo-controlled, double-blind study was designed to evaluate the efficacy of sphinganine on hair loss and hair/scalp quality in vivo. In vitro results showed that sphinganine is a potent inhibitor of 5-α-reductase type I that prevents the conversion of testosterone to dihydrotestosterone, a key factor of androgenetic male baldness. In vivo results demonstrated efficacy in reducing non-illness-related hair loss among males.