Nettle, the plant for hair regrowth?

Losing hair is natural and part of the hair cycle. However, if the hair loss exceeds 150 hairs per day, it is considered abnormal. Numerous factors can trigger a hair loss. Here are the main ones:

• The genetics.

  It is not uncommon for hair loss to be hereditary. For instance, androgenetic alopecia is linked to genetic factors and an increased production of testosterone. However, once this is converted into dihydrotestosterone (DHT) under the influence of the enzyme 5-α-reductase, it accelerates the hair cycle and promotes hair loss.

• Hormonal changes.

  Following childbirth or as menopause approaches, women sometimes experience hair loss. This is due to a decrease in oestrogen levels compared to androgen levels. As previously explained, these androgens accelerate the hair cycle, resulting in hair loss.

• The stress or anxiety.

  When one is stressed over a prolonged period, the body releases a so-called substance P, which is capable of inhibiting the growth of keratinocytes in hair follicles, and can even trigger their entry into apoptosis, that is, their self-destruction. This happens via the production of cytokines that inhibit hair growth.

• Dietary deficiencies.

  Diet has a direct impact on hair health. Studies have particularly highlighted that deficiencies in iron or zinc can potentially cause a reduction in hair growth, or even a condition known as telogen effluvium, which is a type of hair loss affecting the entire scalp.

Please note : this list is not exhaustive and there are other factors that can cause hair loss.

Originating from the temperate regions of Europe and Asia, the nettle is a stinging plant belonging to the Urticaceae family. Often known for its stinging properties, it nonetheless contains an extract rich in benefits for the hair within its leaves and is used in the formulation of hair care products under the INCI name Urtica Dioica Leaf Extract. Antioxidant, the nettle can particularly prevent the appearance of white hair. Moreover, the sebum-regulating properties of this natural ingredient make it an ally of oily scalps. As for hair regrowth, the role of the nettle is more subtle.

prevent hair loss than to stimulate its growth. A study has notably shown that the use of a shampoo based on nettle extract and a serum also containing nettle extract for six months helped to prevent and limit hair loss in 120 individuals suffering from androgenetic alopecia and telogen effluvium. At the end of the six months, the researchers noted a 90% decrease in their hair loss , compared to a 40% decrease in participants who received placebo treatments. Let us note once again that this study highlights the benefits of nettle in combating hair loss, not in promoting regrowth.

From a biological perspective, scientists have linked the ability of nettle to prevent hair loss to its inhibitory action on 5-α-reductase. This enzyme notably catalyses the conversion of testosterone into dihydrotestosterone (DHT). This latter increases the expression of interleukin 6 (IL-6), a cytokine that accelerates the transition between the anagen phase, which corresponds to the hair growth phase, and the catagen phase, or resting phase. DHT thus more rapidly induces hair follicles into the telogen phase, or hair shedding phase. The ability of nettle extract to inhibit the activity of 5-α-reductase therefore allows it to protect hair against hormonal changes or genetic predispositions responsible for an increased production of DHT and consequently hair loss.

• KWACK M. H. & al. Dihydrotestosterone-Inducible IL-6 Inhibits Elongation of Human Hair Shafts by Suppressing Matrix Cell Proliferation and Promotes Regression of Hair Follicles in Mice. Journal of Investigative Dermatology (2012).

• TURKOGLU M. & al. A proprietary herbal extract against hair loss in androgenetic alopecia and telogen effluvium: a placebo-controlled, single-blind, clinicalinstrumental study. Acta Dermatovenerologica (2018).