Nigella sativa oil: what are its benefits for hair?

Although no clinical study has formally demonstrated that applying nigella oil strengthens hair, its composition suggests it could play a role in protecting and enhancing the resilience of hair fibers.

Indeed, 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-oily protective mixture designed to limit dehydration and reduce the impact of external stressors (UV rays, wind, temperature fluctuations…). By supplying lipids similar to those physiologically found on the hair’s surface, applying nigella oil to the hair could help strengthen this lipid barrier—although this effect cannot yet be quantified.

It also contains a significant proportion of palmitic acid, a saturated fatty acid whose structure resembles that of the lipids found in the hair’s cuticle, the outer layer of the hair. By analogy with other vegetable oils containing saturated fatty acids, it is plausible that these lipids could insert themselves between the cuticle scales and contribute to a better cuticle cohesion. This could be of interest because a more coherent cuticle reduces the porosity of the fiber, providing the cortex—the middle layer rich in keratin and essential for hair elasticity—with indirect mechanical protection. This mechanism leads to the hypothesis that using black cumin seed oil could be relevant for dry, weakened, or damaged hair, even though its efficacy remains to be demonstrated.

Applying Nigella sativa oil to hair fibers could also enhance their aesthetic appeal and impart shine. Indeed, as noted above, the saturated fatty acids present in this botanical extract may strengthen the cohesion between the cuticle scales.

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

It should be noted again that in the absence of clinical data, this effect of nigella oil remains hypothetical, though it is consistent with current knowledge of cuticle biology. Furthermore, applying a vegetable oil such as nigella oil also creates a lipid film on the surface, providing an immediate gloss effect and helping to visually enhance the hair’s radiance.

Nigella oil may also act as an ally against scalp tingling, owing to thymoquinone—the active biochemical component in its composition. Indeed, this molecule has anti-inflammatory properties. Studies have specifically shown that thymoquinone reduces the production of pro-inflammatory cytokines, such as interleukins 6 and 12 (IL-6 and IL-12) and tumor necrosis factor alpha (TNF-α).

Furthermore, thymoquinone inhibits the NF-κB nuclear factor signaling pathway. NF-κB plays a crucial role in the production of interleukins 1 and 2 (IL-1 and IL-2), other pro-inflammatory cytokines, and interferon-gamma (IFN-γ) in T lymphocytes. IFN-γ is a cytokine produced as part of the innate immune response and is involved in regulating various inflammatory processes. Therefore, applying black seed oil to the scalp could help to alleviate itching associated with inflammation.

Several studies conducted on the skin suggest that black seed oil has noteworthy anti-inflammatory potential. One experimental study in particular evaluated the anti-inflammatory effect of a balm containing 10% black seed oil, applied topically to the skin of rats. The researchers used a classic model of cutaneous inflammation (carrageenan-induced edema) and observed significant results comparable to those achieved with hydrocortisone, a well-documented anti-inflammatory agent.

Although these data originate from an animal model and cannot be directly extrapolated to the human scalp, they reinforce the idea that nigella seed oil could soothe itching in hair care.

Nigella sativa oil is often recognized for its antioxidant potential, largely due to thymoquinone, one of its most studied active compounds. Several studies conducted on the skin have shown that this molecule, and more broadly nigella 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.

Even though no study has directly evaluated this effect of black seed oil on hair, it is plausible that its antioxidant potential could contribute, at least in theory, to protecting hair fibers from oxidative stress.

It is a well-known factor in the onset of two hair concerns: premature fiber whitening and tip weakening. Indeed, on one hand, the oxidative stress can degrade melanin present in the hair cortex. Free radicals can trigger a series of biochemical reactions that gradually oxidize the pigment, thereby accelerating the appearance of gray hair. In theory, an antioxidant-rich ingredient, such as black seed oil, could help protect melanin integrity for longer.

On the other hand, free radicals can also damage lipids and proteins of the hair fiber, notably keratin, which weakens the cuticle’s cohesion and makes the lengths more prone to breakage and split ends. By reinforcing local antioxidant defenses, black seed oil could therefore help limit this gradual degradation, even though this remains hypothetical in the absence of clinical data.

Many people attribute to black seed oil the ability to stimulate hair growth or to limit hair loss. Indeed, certain biological mechanisms point in this direction. First, its antioxidant properties may contribute to protect the hair follicle bulb from oxidative stress, a factor often implicated in the progressive weakening of the follicle and in certain forms of hair loss. By neutralizing free radicals, black seed oil may therefore help maintain an environment more favorable to hair growth.

Moreover, the anti-inflammatory properties of its flagship compound, thymoquinone, may also be relevant in this context. Studies have shown that it inhibits expression of the COX-2 enzyme as well as the synthesis of prostaglandin D2 (PGD2). This latter molecule exerts an inhibitory effect on the hair follicle. Research has indeed demonstrated the presence of PGD2 at elevated concentrations in areas affected by baldness, and its interaction with the GPR44 receptor in the follicle appears to promote miniaturization. This contributes to the gradual transition from terminal hairs (thick and pigmented) to finer, vellus-like hairs. By reducing PGD2 production, black seed oil could therefore help protect hair from shedding.

Several studies have examined the effects of black seed oil on hair growth. These studies support the idea that black cumin powder or black cumin seed oil could promote hair growth. One investigation evaluated the efficacy of a plant blend, including Nigella sativa (10%), incorporated into coconut oil (60%). The researchers tested the formula on two groups of rats in which a 4 cm² area had been shaved. The first group received a daily application of the oil, while the second group received no treatment. At regular intervals (15, 20, 25, and 30 days), the researchers randomly plucked 15 hairs to measure their length, also assessing the total hair weight. The results showed a markedly greater growth in the treated animals.

The authors suggest that this difference may reflect a premature transition of hair follicles from the telogen phase to the anagen phase, possibly stimulated by antioxidants found in the plant extracts. Although these results do not allow any definitive conclusion about the efficacy of nigella oil alone, they support the idea that some of its components could, in theory, contribute to promoting hair growth.

These findings are supported by a clinical study involving 20 patients with telogen effluvium, a form of diffuse hair loss linked to a premature transition of hair follicles into the telogen phase. Over 3 months, half of the participants applied a lotion containing 0.5% oil of Nigella sativa, while the others received an identical formulation without nigella extract. The results show a significant increase in hair density and thickness among patients who received nigella.

Although further research is still needed, particularly with a larger sample size, this study reinforces the idea that black seed oil could support hair growth.

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