Black seed (Nigella sativa) oil: what are its benefits for hair?

Although no clinical study has formally demonstrated that the application of nigella seed oil strengthens hair, its composition suggests that it may play a role in protecting and reinforcing hair fibers.

The black cumin oil is very rich in unsaturated fatty acids, including oleic acid. The latter is naturally present in the hydrolipidic film that coats the hair fibers, a semi-aqueous, semi-lipid protective layer responsible for limiting dehydration and reducing the impact of external stressors (UV rays, wind, temperature fluctuations…). By supplying lipids similar to those physiologically found on the hair surface, the application of black cumin oil to the hair may help reinforce this lipid barrier—although this effect has yet to be quantified.

It also contains a significant proportion of palmitic acid, a saturated fatty acid whose structure resembles that of the lipids in the cuticle, the hair’s outer layer. By analogy with other plant oils containing saturated fatty acids, it is plausible that these lipids can insert themselves between the scales and contribute to a better cohesion of the cuticle. Yet, a more coherent cuticle reduces the porosity of the fiber, thereby providing the cortex—the keratin-rich intermediate layer essential to hair elasticity—with indirect mechanical protection. This mechanism suggests that the use of black cumin seed oil could be relevant for dry, weakened, or damaged hair, although its effectiveness remains to be demonstrated.

Applying nigella seed oil to hair fibers could also enhance their appearance and luster. As noted above, the saturated fatty acids in this botanical extract could strengthen the cohesion between cuticle scales.

When the structure of the hair fibers is strong and the scales forming their cuticle are properly bonded, the hair appears shinier because it can better reflect light.

In the absence of clinical data, this effect of black seed oil remains hypothetical, but it is consistent with our understanding of cuticle biology. Furthermore, applying a plant oil such as black seed oil also forms a surface lipid film that delivers an immediate gloss effect and helps visually enhance hair shine.

Nigella seed oil could also help soothe scalp tingling and itching thanks to thymoquinone, a compound with anti-inflammatory properties. This molecule helps to reduce the production of pro-inflammatory mediators and to calm excessive skin reactions. Several studies on skin suggest that nigella seed oil has genuine soothing potential. In a standard experimental model of skin inflammation (carrageenan-induced edema), a balm containing 10% nigella seed oil reduced inflammation to a degree comparable to a reference anti-inflammatory agent (hydrocortisone). These results suggest that applying it to the scalp may help relieve inflammation-related discomfort.

Although these data derive from an animal model and cannot be directly extrapolated to the human scalp, they bolster the idea that black cumin (nigella) oil may ease itching in hair-care applications.

The Nigella sativa oil is often cited for its antioxidant potential, largely due to thymoquinone. Several studies conducted on the skin have shown that this molecule and, more broadly, Nigella sativa oil, can stimulate the activity of endogenous antioxidant enzymes such as superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase. These enzymes play a key role in neutralizing free radicals.

Although no study has directly evaluated this effect of black seed oil on hair, it is plausible that its antioxidant potential could, at least in theory, help protect hair fibers from oxidative stress.

This factor is a well-known contributor to the emergence of two hair concerns: the premature whitening of the fibers and fragility of the hair ends. On one hand, free radicals can initiate a cascade of biochemical reactions that progressively oxidize the melanin within the cortex, thereby accelerating the appearance of gray hair. In theory, an antioxidant-rich ingredient such as nigella seed oil could help preserve melanin integrity for a longer period.

Moreover, free radicals can also damage lipids and proteins of the hair fiber, particularly keratin, which weakens the cuticle’s cohesion and makes lengths more vulnerable to breakage and split ends. By boosting local antioxidant defenses, black seed oil could therefore help limit this progressive degradation.

The Nigella sativa oil is often associated with beneficial effects on hair growth and limiting hair loss, and some biological mechanisms also point in that direction. Its antioxidant properties could help to protect the hair bulb from oxidative stress, a factor often involved in the progressive weakening of the follicle and in some forms of hair loss, thus contributing to a more favorable environment for hair growth.

Furthermore, thymoquinone present in black seed oil exhibits anti-inflammatory properties that may influence hair loss. Studies have shown that it notably inhibits the expression of the COX-2 enzyme and the synthesis of prostaglandin D2 (PGD2), a molecule identified at high concentrations in balding areas. Its interaction with the GPR44 receptor in the follicle appears to promote follicular miniaturization, meaning the gradual transition from so-called terminal hairs (thick and pigmented) to finer, vellus-like hairs. By reducing PGD2 production, black seed oil could thus contribute to limiting hair loss.

Several studies support the idea that black cumin seed powder or black seed oil may promote hair growth. One study evaluated the efficacy of a formulation containing Nigella sativa (10%) incorporated into coconut oil (60%). They tested the formula on groups of rats in which a 4 cm² area had been shaved. At regular intervals (15, 20, 25, and 30 days), researchers randomly collected 15 hairs to measure their length, while also assessing the total hair weight. The results show asignificant increase in hair growth compared to the control groups.

The authors suggest that this difference could reflect apremature shift of hair follicles from the telogen phase to the anagen phase, possibly stimulated by antioxidants present in the plant extracts. Although these results do not allow conclusions about the efficacy of black seed oil alone, they reinforce the idea that certain of its components could, in theory, help support hair growth.

These findings are supported by a clinical study involving 20 patients with telogen effluvium, a diffuse form of hair loss associated with the premature transition of hair follicles into the telogen phase. Over a three-month period, half of the participants applied a lotion daily containing 0.5% oil from Nigella sativa, while the others received an identical formulation but without nigella extract. The results show a significant increase in hair density and thickness among the patients who received the nigella extract.

Although additional research is still necessary, especially with a larger sample size, this study reinforces the idea that Nigella sativa oil may support hair growth.

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