Safflower oil to stimulate hair growth?

The dye thistle, also known as the dyer's saffron, is a herbaceous dyeing and oil-producing plant from the Asteraceae family. Originating from Turkey and Iran, the dye thistle is now cultivated all over the world for the oil present in its seeds. Preferably extracted by cold pressing, this light vegetable oil possesses several benefits for the skin and hair derived from its biochemical composition rich in interesting active ingredients. It is even credited with the ability to stimulate hair growth, a hypothesis supported by several elements.

The linoleic acid and β-sitosterol found in safflower oil have an activating effect on the Shh/Gli signalling pathway. This pathway impacts the hair cycle and promotes the transition between the telogen and anagen phases of follicular cells. The telogen phase corresponds to the moment when the hair detaches from its hair follicle and falls out, while the anagen phase corresponds to the hair growth phase. By stimulating the telogen-anagen transition, safflower oil somewhat accelerates hair growth.

Furthermore, an in vitro study has highlighted that safflower oil has a 5-alpha-reductase inhibitory effect. This enzyme catalyses the conversion of testosterone into dihydrotestosterone (DHT). DHT, in turn, increases the expression of interleukin 6 (IL-6), a cytokine that accelerates the transition from the anagen phase to the catagen phase, or resting phase, during which the hair stops growing but remains attached to its hair follicle. DHT thus causes hair follicles to enter the telogen phase (the shedding phase) more quickly. Therefore, the ability of safflower oil to inhibit the activity of 5-alpha-reductase does not allow it to accelerate hair growth per se, but rather to slow down their loss.

Furthermore, a study conducted on rats has shown that the topical application of a 1% safflower oil solution stimulated their hair growth twice as much as a 2% minoxidil solution. Minoxidil is an active substance often incorporated into treatments for alopecia. Its topical application stimulates the growth of keratinocytes, which helps to prolong the hair growth phase. Minoxidil is generally used at concentrations between 2 and 5% in treatments for alopecia.

Note : Despite the promising results, caution should still be exercised regarding the ability of safflower oil to stimulate hair growth. Indeed, the studies mentioned above were all conducted in vitro or on rats. In vivo studies on human scalps would be beneficial and could confirm the effect of safflower oil on hair growth.