Nettle for oily hair?

Oily hair can alter the appearance of a head of hair, making it heavy and unattractive. The rapid greasing of hair is due to a high sebum production by the sebaceous glands. While sebum is essential for the protection and hydration of the scalp and hair fibers, overproduction can also have negative consequences. Hyperseborrhea can particularly promote the appearance of dandruff , which are small dead cells ranging in color from white to yellow. Dandruff is indeed commonly associated with the colonization of the scalp by the fungus Malassezia, which feeds on the triglycerides present in sebum. In doing so, they contribute to the release of prostaglandins, inflammatory mediators responsible for sensations of discomfort and itching. There are several factors responsible for oily hair:

• A hormonal origin.

  Hyperserborrhea is often due to a high production of androgen hormones. The main androgen in men is testosterone, and in women, it is Δ-4-androstenedione and dehydroepiandrosterone. Within the sebocyte, these androgens are transformed by various enzymes into testosterone. This testosterone then reacts under the action of an enzyme, the 5-α-reductase, to transform into dihydrotestosterone which stimulates the activity of the sebaceous glands. Therefore, individuals whose 5-α-reductase is very active are more prone to having oily hair.

• The role of external aggressions.

  The increase in external aggressions also contributes to making hair oily. Pollution, UV rays, unsuitable hair products... All these factors lead to an over-stimulation of the sebaceous glands and the production of an excess of sebum to protect the scalp.

• Nutrition.

  There is also a connection between diet and oily hair. Indeed, frequent consumption of high glycemic index foods, such as white bread, fries, or certain cookies, generates a spike in insulin in the blood. This increase in insulin levels also triggers a rise in androgen levels, which indirectly leads to excessive sebum secretion.

The nettle is a perennial herbaceous plant characterized by its serrated leaves and stems covered with stinging hairs. Despite this feature, thenettle has numerous beneficial properties for skin and hair applications. It is particularly known for its anti-inflammatory, antioxidant, antibacterial, and also purifying effects. Therefore, nettle is a plant often found in cosmetic treatments intended for individuals with oily skin or hair.

This natural ingredient indeed helps to regulate sebum production due to its ability to inhibit 5-α-reductase, the enzyme mentioned above that catalyzes the conversion of testosterone into dihydrotestosterone (DHT). When DHT binds to a specific cytosolic receptor located in the sebaceous glands, it triggers an increase in the activity of the sebaceous glands, and therefore an intensification of sebum synthesis. By inhibiting this process, nettle thus helps to combat oily hair. Regular use of a nettle-based hair care product can help individuals whose hair quickly becomes greasy to control sebum production at their scalp level and allow them to space out their shampoos.

• BEYLOT G. Les cheveux gras. Actualités pharmaceutiques (2013).

• SEMALTY A. & al. A comprehensive review on phytochemistry and pharmacological effects of stinging nettle (Urtica dioica). Current Traditional Medicine (2017).