Black seed is known by many names such as Nigella sativa, kalonji, and black cumin seed. The oil is extracted from the seeds of the Nigella sativa plant, which grows in the Mediterranean region and in southwest Asia.
While black seeds taste slightly bitter, it is used as a flavoring or spice in various dishes worldwide. Aside from its culinary purposes, the oil from black seed has the capacity to treat a wide range of medical maladies. Its medicinal properties is thought to be can be attributed to thymoquinone (TQ), a compound known to possess potent antioxidant properties.
Black seed has a long history as a therapeutic option for a wide range of diseases. In fact, the Assyrians in ancient Egypt used this beneficial herb for the treatment of gastrointestinal problems, skin diseases, and various inflammatory conditions.
Interestingly, black seed oil was found in the tomb of the Egyptian Pharaoh Tutankhamen, suggesting that it was used by the elite people of ancient Egypt. In biblical times, it was referred to as "curative black cumin." The great Greek physicians Hippocrates and Dioscorides also described black seed as "Melanthion" while the Romans called it “Greek Coriander.”
Health Benefits of Black Seed Oil
There is a large body of evidence suggesting that the health benefits of black seed oil can be attributed to its potent anti-inflammatory and antioxidant properties.
1. Improves Arthritis Symptoms
Black seed oil can help provide long-lasting pain relief in people with arthritis.
A study of patients with rheumatoid arthritis found that the group who took Nigella sativa oil capsules 500 mg twice daily for 1 month had a significant improvement in the number of swollen joints and the duration of morning stiffness, compared with the group who consumed starch-filled capsules daily for the same period of time. 
In a similar study of patients with rheumatoid arthritis, it was found that the group who received two capsules (500 mg each) of Nigella sativa oil daily for 8 weeks had lower blood levels of malondialdehyde (marker of oxidative stress and inflammation) compared with subjects who took two paraffin capsules daily for the same period of time. 
In a study of elderly patients with knee osteoarthritis, it was found that skin application of Nigella sativa oil on the knee joint every 8 hours for 3 weeks provided significant pain relief. 
2. Improves Cholesterol Levels
Black seed oil can also help bring down cholesterol levels.
A recent review of several studies found that black seed oil has a greater effect in reducing total cholesterol, low-density lipoprotein (bad cholesterol), and triglyceride levels than black seed powder. 
A study of type 2 diabetic patients found that the group who consumed black seed oil at 2 grams per day had a significant decline in total cholesterol, triglycerides, and low-density lipoprotein cholesterol levels, and a significant elevation in high-density lipoprotein (good cholesterol) levels compared with the group who took black seed oil at 1 gram per day and the group who consumed black seed oil at 3 grams per day. 
3. Reduces High Blood Pressure
Supplementation with black seed oil can benefit people with hypertension.
In a study of healthy volunteers, a significant reduction in systolic and diastolic blood pressure was observed in the group treated with 2.5 ml black seed oil for 8 weeks compared with placebo-treated group.
A study assessing the effects of black seed oil in patients with mild hypertension found that 100 and 200 mg doses were effective at reducing systolic and diastolic blood pressure compared with placebo. 
4. Promotes Healthy Skin
Evidence suggests that black seed oil can help treat various skin conditions.
In a study of patients with vitiligo, a skin condition characterized by loss of skin color in patches, it was found that skin application of black seed oil reduced more skin lesions than fish oil. 
In a rat model of psoriasis, skin application of black seed oil strongly inhibited psoriasis-like inflammation and skin changes induced by the drug imiquimod. 
5. Treats Diabetes
The anti-diabetic effect of black seed oil is also backed by a number of studies.
A 2019 review published in the International Journal of Environmental Research and Public Health found that black seed oil significantly improved laboratory parameters of hyperglycemia (high blood sugar levels) and diabetes control. 
In a study investigating the effects of black seed in patients with type 2 diabetes mellitus, it was found that consumption of capsules containing Nigella sativa at a dose of 1, 2 and 3 g/day for three months significantly lowered blood sugar levels without any adverse effects. 
One review found that black seed oil can improve blood sugar levels in patients with type 2 diabetes mellitus through various important mechanisms, including its potent antioxidant properties and beneficial effects on insulin secretion and blood sugar absorption. 
6. Treats Asthma
There’s also a number of studies supporting the beneficial effects of black seed oil on lung conditions such as asthma.
A recent rat study reported that black seed oil can help improve symptoms of asthma by inhibiting histamine release, which in turn reduces airway inflammation. 
A recent review of multiple studies assessing the effects of black seed oil on asthma also found that the treatment alleviated airway inflammation by inducing dilation of blood vessels and reducing inflammatory substances. 
7. Fights Obesity
Taking black seed oil can help improve body composition by promoting weight loss.
In a clinical trial investigating the effects of the combination of black seed oil and aerobic training on the body composition of sedentary overweight females, researchers found that the treatment lowered body mass index (BMI) after 8 weeks. 
A study also found that obese women who consumed a low-calorie diet together with 3 g per day of black seed oil for 8 weeks had significant reduction in weight and waist circumference compared with the placebo group. 
8. Relieves Breast Pain
Application of black seed oil can also produce significant pain relief.
In one clinical study of women suffering from breast pain due to menstruation, application of a gel containing 30% black seed oil at painful areas 2 times a day for 2 menstrual cycles significantly reduced pain compared with placebo treatment. 
9. Aids in Proper Digestion
Thymoquinone, the main constituent of black seed oil, is known to aid in proper digestion.
In one study assessing the gastrointestinal effects of black seed, it was found that thymoquinone increased the production of mucin, a large glycoprotein that helps in proper digestion of food.  Mucin also protected the gastrointestinal tract against foreign invaders.