Focus on black cumin

1 - Introduction

Nigella sativa has been used for millennia in medical systems such as Unani, Ayurveda and Arabic medicine. Its oil, extracted from the seeds, is attracting scientific interest thanks to its particular composition and varied pharmacological effects: anti-inflammatory, antioxidant, immunomodulator, antimicrobial, anticancer, cardiometabolic, dermatological, respiratory, digestive and neurological [1].

2 - Phytochemical composition

Nigella sativa oil contains a complex blend of compounds including fatty acids, bioactive terpenes, sterols, tocopherols and a fraction of essential oils.

2.1 - Main active compounds

The oil's main bioactive compound is thymoquinone (TQ), regularly reported as the major quinone in the volatile fraction, to which much of its therapeutic effects are attributed ([3], [4]).

Thymoquinone is associated with the oil's anti-inflammatory, antioxidant and anticancer activities. In addition to TQ, the oil contains other quinones such as thymohydroquinone and dithymoquinone (also known as nigellone), as well as volatile terpenes such as p-cymene, α-thujene, carvacrol and thymol[5]

The fatty acids present in Nigella sativa oil are predominantly unsaturated, with linoleic acid (omega-6) as the main component, generally accounting for between 50% and 60% of the lipid profile [6].

Oleic acid (omega-9), another important fatty acid, is also present in significant quantities, followed by saturated fatty acids such as palmitic and stearic acids ([7], [6]). Other minor fatty acids, such as linolenic acid, arachidic acid and eicosadienoic acid, also contribute to the oil's nutritional and pharmacodynamic profile [6].

Other bioactive components include phytosterols (such as β-sitosterol, stigmasterol and campesterol) and tocopherols (compounds of vitamin E), which participate in the oil's antioxidant stability and its potential cholesterol-lowering effects ([6], [8]).

2.2 - Differences between cold-pressed oil and essential oil

Nigella sativa oil can be obtained by various extraction methods. Cold pressing yields the fixed oil, rich in fatty acids, sterols and fat-soluble vitamins. This method retains non-volatile compounds, including thymoquinone, although the latter is present in a matrix dominated by fatty acids [6].

In contrast, the essential oil, obtained by steam distillation or supercritical CO₂ extraction, concentrates the volatile fraction, dominated by monoterpenes and oxygenated compounds such as thymoquinone, p-cymene, thymol and carvacrol ([9], [5]).

So, while cold-pressed oil is valued for its complete lipid and nutritional profile, essential oil stands out for its highly bioactive volatile compounds, with powerful antimicrobial and antioxidant properties [10].

3 - Therapeutic effects human and preclinical data

Nigella sativa oil acts on numerous biological systems. Research highlights the diversity of its therapeutic effects, presented in the following subsections.

3.1 - Anti-inflammatory effects

Preclinical and emerging clinical studies have shown that Nigella sativa oil exerts powerful anti-inflammatory effects. Inhibition of inflammatory mediators such as prostaglandins, leukotrienes, cytokines (notably IL-6, TNF-α, IL-1β) as well as modulation of the NF-κB signaling pathway, are mainly attributed to thymoquinone and related compounds ([1], [9]). This action justifies its use in inflammatory pathologies such as rheumatoid arthritis, asthma and chronic inflammatory bowel disease (Clinical Trials Search: Nigella sativa OR black seed oil OR black cumin oil).

3.2 - Antioxidant properties

Nigella sativa oil is rich in antioxidants. Its antioxidant capacity comes mainly from thymoquinone, tocopherols and various polyphenols. These compounds increase the activity of endogenous antioxidant enzymes such as glutathione peroxidase, catalase and superoxide dismutase, neutralizing reactive oxygen species and reducing lipid peroxidation ([11], [8]). This action contributes to its therapeutic potential in pathologies linked to oxidative stress, including neurodegenerative diseases and carcinogenesis.

3.3 - Immunomodulating effects

Beyond its antioxidant and anti-inflammatory properties, Nigella sativa oil modulates immune function. Studies indicate that it acts on both innate and adaptive immunity, modulating cytokine production, enhancing NK (Natural Killer) cell activity, and adjusting the balance between different T-cell subtypes. These effects are mainly mediated by thymoquinone and other quinone derivatives ([3], [9]). These results support its potential interest in the management of autoimmune diseases and the reinforcement of defenses against infections.

3.4 - Antimicrobial and antiparasitic properties

The antimicrobial action of Nigella sativa oil is well documented. It demonstrates broad-spectrum activity against Gram+ and Gram- bacteria, viruses, fungi and certain parasites. These effects are partly attributed to the disruption of microbial cell membranes by volatile compounds such as thymoquinone and p-cymene, as well as to the inhibition of key microbial enzymes ([11], [5]). Synergistic effects have also been observed when combined with conventional antibiotics, suggesting potential as adjuvant therapy in the face of resistant infections.

3.5 - Anticancer potential

Preclinical studies reveal that Nigella sativa oil possesses anticancer properties. Proposed mechanisms include induction of apoptosis, inhibition of cell proliferation and modulation of cell cycle regulatory proteins, effects mediated mainly by thymoquinone. The oil could also enhance the cytotoxic effect of certain chemotherapeutic agents, although further clinical research is needed to confirm these effects in humans (abdullahAli2023nigellasativatherapeutic pages, [9], [12]).

3.6 - Cardiometabolic benefits

The cardiometabolic effects of Nigella sativa oil represent one of the most promising areas of research. Experimental studies have shown that the oil can:

• Improve lipid profile: lower total cholesterol, LDL, triglycerides; higher HDL.
• Reduce blood pressure, through vasodilator effects and calcium channel inhibition.
• Improve insulin sensitivity, making it an asset in the management of metabolic syndrome and type 2 diabetes ([6], [9]).

3.7 - Dermatological applications

Nigella sativa oil is widely used in traditional medicine to treat skin conditions such as eczema, acne, and to promote wound healing. Its antimicrobial and anti-inflammatory properties contribute to its effectiveness in treating dermatological disorders, while its antioxidant components support skin regeneration and reduce oxidative damage ([10], [4]). Topical formulations have shown potential in reducing inflammation and healing mild skin lesions.

3.8 - Respiratory, digestive and neurological applications

In respiratory pathologies, Nigella sativa oil is used as adjuvant therapy in asthma and chronic rhinitis, due to its bronchodilator and anti-inflammatory effects. Clinical trials have investigated its role in improving lung function and reducing inflammatory mediators in asthmatic patients [13]. Similarly, its gastroprotective properties, such as strengthening mucosal defenses and modulating intestinal microbiota, support its traditional use in the management of digestive disorders [1]. On the neurological front, thymoquinone's neuroprotective and anti-inflammatory activities have been implicated in the protection of dopaminergic neurons, with potential in reducing the symptoms of neurodegenerative diseases [3].

4 - Clinical trials

Numerous well-designed clinical studies have evaluated the efficacy and safety of Nigella sativa oil in a variety of therapeutic contexts. For example, the clinical trial [13] investigated the effect of black cumin oil supplementation at 1 g/day for 4 weeks in asthmatic patients, assessing asthma control score (ACT), lung function and inflammatory mediator levels. Results showed an improvement in clinical symptoms, with a safety profile deemed acceptable [13].

Other trials, such as [14] and [15], evaluated the efficacy of oil in respiratory conditions such as chronic rhinitis and pediatric pneumonia, using standardized endpoints: symptom scales, inflammatory biomarkers and length of hospital stay ([14], [15]).

In another trial [16], Nigella sativa oil was tested as an adjuvant to atorvastatin in patients with hyperlipidemia. The dose used was 1000 mg daily for eight weeks, with monitoring of lipid parameters, liver and kidney function. Results showed an improvement in cholesterol levels, with no notable short-term adverse effects [16].

A trial investigating the effects of oil in gonarthrosis (osteoarthritis of the knee) [17] also showed benefits in terms of pain relief and improved physical function, with few adverse events reported [17].

Finally, a study combining black cumin oil supplementation with dietary interventions targeting adiposity [18] showed promising improvements in lipid profile and body composition [18.1].

Overall, these human clinical studies consistently suggest that Nigella sativa oil can improve clinically relevant indicators, with few, mostly mild side effects (such as mild digestive disturbances), and no serious adverse effects requiring discontinuation of treatment ([13], [16], [17]).

5 - Traditional uses

Present in Unani, Ayurveda, Arabic systems: used against respiratory, digestive diseases, rheumatism, epilepsy, paralysis, hepatitis, diabetes, cardiovascular diseases, skin conditions, menstrual disorders, migraines, back pain, etc. Modes: oral, topical, inhalation [2]

6 - Administration modes

• Oral: crude oil or capsules, doses 1 g/d up to 2 × 900 mg, over 4-8 weeks.
• Topic: pure or diluted on lesions (eczema, wounds, inflammation).
• Inhalation: little documented clinically, but promising for the respiratory tract.

7 - Safety and contraindications

The safety profile of Nigella sativa oil is favorable overall, with several studies reporting low toxicity when the oil is administered at therapeutic doses.

7.1 - Toxicity data

Preclinical studies indicate that the oral LD50 (median lethal dose) of thymoquinone in animals is several hundred mg/kg, while the effective therapeutic dose is around 100 to 150 times lower than this toxic dose. Furthermore, clinical trials have mainly reported mild, transient side effects, such as nausea or bloating, with no serious adverse events associated with short-term use [19].

7.2 - Drug interactions and contraindications

Although Nigella sativa oil appears to be well tolerated, caution is advised when combined with drugs affecting blood coagulation, as it may exert a mild antiplatelet effect. Patients with severe hepatic or renal impairment have generally been excluded from clinical trials, so its safety in these populations remains poorly documented[16]

7.3 - Use during pregnancy, lactation and in children

Safety data in pregnant or breast-feeding women are limited, which is why the majority of clinical trials have excluded these groups to avoid any risk. Similarly, pediatric use of black cumin oil has been little studied to date.

Therefore, caution is recommended, and further research is needed to establish safe dosing recommendations for these particular populations ([15.1], [13.1])

8 - Discussion

The varied phytochemical composition of Nigella sativa oil including thymoquinone, potent unsaturated fatty acids, phytosterols, tocopherols and volatile compounds forms the basis of its broad therapeutic potential. While the cold-pressed oil, rich in fatty acids and fat-soluble antioxidants, offers robust nutritional and pharmacological benefits, the essential oil fraction, concentrated in volatile compounds such as thymoquinone and p-cymene, exhibits particularly marked bioactivity in antimicrobial and antioxidant uses [6].

This review also highlights how emerging human clinical studies are translating traditional uses of Nigella sativa into modern therapeutic interventions. For example, the efficacy of black cumin oil in improving asthma control, lipid profiles and inflammatory markers provides a rational, evidence-based basis for its continued clinical use. Furthermore, its use in dermatology aligns with its antimicrobial and anti-inflammatory properties, which are also relevant to wound care and the management of skin disorders ([13], [16], [4])

From an ethnopharmacological perspective, Nigella sativa's historical use within various traditional medical systems remains a mainstay of its current scientific study. Its ancient reputation in Unani, Ayurvedic and prophetic medicine illustrates a holistic approach that contemporary research is beginning to validate through systematic investigation ([2], [1]).

The oral, topical and inhalation modes of administration reflect a versatility that enables therapeutic effects to be targeted according to the pathology to be treated. However, the variability of extraction methods highlights the need to standardize oil composition in order to guarantee reproducible therapeutic effects [5].

9 - Clinical implications and avenues for future research

Data from clinical trials suggest that Nigella sativa oil is safe and effective in short-term use for conditions such as:

• hyperlipidemia,
• asthma,
• chronic rhinitis
• arthritis of the knee.

Future research should focus on the following areas:

• Standardization and quality control of extraction methods, to reliably quantify thymoquinone and other active constituents[6].
• Conducting large-scale, placebo-controlled clinical trials across a range of indications, to assess long-term safety and clinical efficacy.
• Evaluating the synergistic potential of Nigella sativa oil with conventional treatments, particularly in chronic inflammatory disorders and metabolic diseases.
• Pharmacokinetic and pharmacodynamic characterization of the two fractions: the fixed oil obtained by cold pressing and the essential oil derived from distillation or supercritical extraction.
• In-depth mechanistic studies, in vitro and in vivo, to elucidate the molecular mechanisms involved in its immunomodulatory and anticancer effects ([12], [9]).

10 - Conclusion

Nigella sativa oil emerges as a multifaceted therapeutic agent, whose benefits are based on a complex phytochemical matrix. Its main active compound, thymoquinone, combined with a range of fatty acids, phytosterols and other volatile compounds, gives it:

• anti-inflammatory,
• antioxidant,
• immunomodulatory,
• antimicrobial,
• cardiometabolic properties.

Clinical data support its role in:

• improving lung function in asthmatics,
• modulating the lipid profile in hyperlipidemia,
• relieving pain and inflammation in osteoarthritis,

Traditional uses and modern research evidence are converging, offering a strong rationale for encouraging research and clinical integration of this natural product. However, efforts are still needed regarding standardization, choice of extraction methods, and well-controlled long-term studies.

All in all, Nigella sativa oil remains a promising candidate in the field of nutraceuticals and complementary medicine, buoyed by both the wisdom of ancient knowledge and contemporary scientific advances ([3], [8], [13]).

11 - Future prospects

For Nigella sativa oil to be further integrated into conventional medicine, future research will need to focus on:

• The integration of omics technologies (such as metabolomics) to comprehensively characterize its phytochemical profile and bioactivity.
• The development of standardized formulations, based on solid pharmacokinetic data.
• The assessment of the impact of geographical and agronomic factors on its chemical composition.
• The study of its potential in combination therapies, given its synergistic effects with certain conventional treatments.

12 - Summary

In summary, Nigella sativa oil is distinguished by its rich phytochemical composition, the source of its many therapeutic properties. The differences between cold-pressed oil and essential oil reflect distinct extraction methods and divergent chemical profiles:

• the former provides a complete lipid matrix with nutritional benefits,
• the latter offers a high concentration of volatile bioactive compounds such as thymoquinone.

Clinical trials confirm its potential in the management of asthma, hyperlipidemia and inflammatory conditions, with an excellent safety profile. Its roots in traditional medicine further strengthen the credibility of its multiple applications. However, further standardization efforts and long-term studies are essential if its therapeutic potential is to be fully exploited and integrated into evidence-based clinical practice ([13], [18]).

This review highlights the importance of Nigella sativa oil as a natural substance with multiple health benefits. Its history in traditional medicines, combined with recent data from preclinical and clinical studies, supports its role as a promising adjuvant to conventional therapies in a variety of medical contexts.

Further research will be essential to:

• optimize its use,
• establish dosing recommendations,
• determine precisely its mechanisms of action,

Scientific references