Ginseng for hair growth?

The hair originates in the hair follicle before growing in successive cycles, and then falling out. They grow independently of their neighbours, as each hair follicle has its own life. The hair has a lifespan based on three different phases that renew each time:

• Anagen phase: this is the growth phase of the hair. It lasts for two to five years. The synthesis and pigmentation of the hair shaft only occur during this phase. Thus, the hair grows approximately 1 cm per month.

• Catagen phase: This is a "resting" phase that lasts 2 to 3 weeks, during which the hair stops growing but remains attached to its hair follicle.

• Telogen phase: it lasts 3 months. At the end of these 3 months, the hair falls out and detaches from its hair follicle, which is already starting to produce a new hair.

Typically, each hair follicle undergoes between 25 and 30 cycles throughout its lifetime. For your information, it is entirely normal to lose 50 to 100 hairs per day. However, certain factors can promote hair loss prematurely: hormonal fluctuations, stress, nutritional deficiencies, seasonal changes, or medicinal treatments.

It is then possible to turn to ingredients that promote hair growth, such as ginseng, which has often been described as an ingredient that stimulates hair growth, but is this really the case?

A study conducted in 2018 on mice demonstrated that linoleic acid and β-sitosterol found in the root of red ginseng could activate the Shh/Gli signalling pathway. This pathway regulates the development of hair follicles during embryonic life, and influences the cycle and growth of hair follicles in adults by promoting the telogen-anagen transition of follicular cells.

The article also highlights the importance of the Wnt/β-catenin signalling pathway in the differentiation of epidermal stem cells. It is crucial for the fate of epithelial stem cells, as keratinocytes adopt an epidermal destiny in the absence of β-catenin. Ginsenoside F2 increased the expression of β-catenin and its transcriptional coactivator Lef-1, leading to an increase in the number of hair follicles in the anagen phase, suggesting that ginsenoside F2 induces the anagen phase.

Thus, these studies have demonstrated that ginseng and ginsenosides regulate the expression and activity of the main proteins involved in the phases of the hair cycle. The hair growth promoted by ginseng metabolites is associated with the induction of anagen phases and the delay of catagen phases. Although these studies are promising, further research, particularly on human trials, is necessary to establish a link between ginseng and hair growth in humans.

• CHOI B. Y. Hair-growth potential of ginseng and its major metabolites: a review on its molecular mechanisms. International Journal of Molecular Sciences (2018).