Effect of applying Lactiplantibacillus plantarum subsp. plantarum N793 to the scalps of men and women with thinning hair: a randomized, double-blind, placebo-controlled, parallel-group study.

Lactiplantibacillus plantarum subsp. plantarum N793 (N793) is a lactic acid bacterium (LAB) isolated from corn. We previously showed that N793 increases the level of keratinocyte growth factor, which is required for hair growth, in the culture supernatant of human follicle dermal papilla cells. Additionally, an open-label, single-arm study reported that applying a lotion containing N793 to the scalp for 24 weeks improved hair density in men and women with thinning hair. The present study was a double-blind, placebo-controlled, parallel-group study aimed at verifying the efficacy of N793 for thinning hair. A lotion containing N793, and a control lotion (placebo) were applied once daily for 24 weeks to 104 healthy Japanese men and women. Analysis of all participants revealed no difference in hair density between the N793 and placebo groups. However, an additional analysis limited to participants with relatively mild progression of thinning hair showed a significantly better hair density in the N793 group than in the placebo group. These findings suggest that topical application of N793 improves thinning hair in men and women when the condition's progression is relatively mild.