Black seed oil is derived from the plant Nigella sativa. It may be applied to the skin or taken as an oral supplement.
Nigella sativa (N. sativa) is a small flowering herb native to Southwest Asia, the Middle East, Southern Europe, and North Africa.
The plant produces fruit that contains tiny black seeds. Often called simply black seed, N. sativa seeds are known by several other names, including black cumin, black caraway, nigella, fennel flower, and Roman coriander (, 3).
Black seed oil is pressed from N. sativa seeds and has been a part of traditional remedies for more than 2,000 years thanks to its purported therapeutic properties.
Research indicates it might have multiple health applications, such as aiding asthma treatment and supporting weight reduction. It’s also used topically for potential skin and hair benefits.
This article examines the possible health advantages of black seed oil, along with side effects and dosing considerations.
Possible health benefits of black seed oil
In traditional healing systems, black seed oil has been used for a range of ailments. Because of this wide array of traditional uses, it has sometimes been dubbed a “panacea” or cure-all.
Although not every claimed use is supported by definitive evidence, black seed oil and its constituent compounds have been associated with several health advantages.
Rich in antioxidants
Black seed oil contains abundant antioxidants — plant-derived compounds that help shield cells from damage caused by unstable molecules called free radicals.
Antioxidants are crucial for health; studies show they can reduce inflammation and help protect against illnesses such as heart disease, Alzheimer’s disease, and cancer.
Notably, black seed oil is a good source of thymoquinone, a compound with strong antioxidant and anti-inflammatory actions. Research indicates thymoquinone may help preserve brain function and assist in treating certain cancers.
May assist in treating asthma
Asthma is a long-term condition in which airway linings swell and the surrounding muscles tighten, making breathing difficult.
Studies suggest black seed oil — particularly thymoquinone — may aid asthma management by reducing inflammation and relaxing the airway muscles.
In one trial involving 80 adults with asthma, taking 500 mg of black seed oil capsules twice daily for 4 weeks led to significant improvements in asthma control.
These findings are encouraging, but larger and longer trials are required to evaluate the long-term safety and efficacy of black seed oil for asthma.
May support weight-loss efforts
Although the precise mechanism remains unclear, research shows black seed oil might help reduce body mass index (BMI) in people with obesity, metabolic syndrome, or type 2 diabetes (, 19, ).
In an 8-week study, 90 women aged 25–50 with obesity followed a low-calorie diet and received either a placebo or 1 gram of black seed oil per meal (3 grams daily total).
By the study’s end, those taking black seed oil lost significantly more weight and experienced a greater reduction in waist circumference than the placebo group. The oil group also showed notable improvements in triglyceride and LDL (bad) cholesterol levels.
Despite these promising outcomes, additional research is needed to determine the long-term safety and effectiveness of black seed oil for weight loss.
May reduce blood sugar levels
For people with diabetes, chronically high blood sugar raises the risk for complications such as kidney disease, eye disease, and stroke.
Several trials in individuals with type 2 diabetes indicate that 2 grams per day of crushed whole black seeds can significantly lower fasting blood glucose and hemoglobin A1c (HbA1c), a marker of average blood sugar over 2–3 months.
While many studies use powdered black seed in capsules, oil extracts have also demonstrated blood sugar–lowering effects.
One study of 99 adults with type 2 diabetes reported that both 1/3 teaspoon (1.5 mL) and 3/5 teaspoon (3 mL) daily of black seed oil for 20 days significantly reduced HbA1c compared with placebo (26).
May help reduce blood pressure and cholesterol
Black seed oil has been explored for its potential to lower blood pressure and cholesterol.
Elevated blood pressure and high total or LDL (bad) cholesterol are major risk factors for cardiovascular disease.
Two studies — one with 90 women with obesity and another with 72 adults with type 2 diabetes — found that taking 2–3 grams of black seed oil capsules per day for 8–12 weeks significantly reduced LDL and total cholesterol (, 28).
Another trial in 90 people with elevated cholesterol showed that consuming 2 teaspoons (10 grams) of black seed oil after breakfast for 6 weeks significantly decreased LDL levels (29).
The oil may also help lower blood pressure. One study in 70 healthy adults reported that 1/2 teaspoon (2.5 mL) of black seed oil twice daily for 8 weeks significantly lowered blood pressure versus placebo.
Although results are promising, the body of evidence is limited and more research is necessary to determine optimal dosing.
May support brain health
Neuroinflammation — inflammation of brain tissue — is believed to contribute to conditions such as Alzheimer’s and Parkinson’s disease.
Early laboratory and animal studies suggest thymoquinone in black seed oil may reduce neuroinflammation, potentially offering protection against brain disorders like Alzheimer’s and Parkinson’s.
However, human research on black seed oil’s effects on the brain is sparse.
One trial in 40 healthy older adults found improvements in memory, attention, and cognition after taking 500 mg of N. sativa capsules twice daily for 9 weeks.
Still, additional human studies are needed to confirm any protective cognitive effects of black seed oil.
May be beneficial for skin and hair
Beyond medicinal uses, black seed oil is widely applied topically to address various skin concerns and to condition hair.
Due to its antimicrobial and anti-inflammatory properties, research indicates black seed oil may assist with several skin conditions, including (, 37, ):
- acne
- eczema
- dry skin
- psoriasis
Although it’s often suggested that the oil can moisturize hair and reduce dandruff, there are no clinical trials confirming those claims.
For readers interested in topical hair preparations, this article’s discussion of hair benefits pairs naturally with information about black castor oil for hair, which is another oil commonly used for scalp and hair care.
Other possible benefits
Black seed oil might offer additional health benefits, such as:
- Anticancer activity. Laboratory studies show thymoquinone can inhibit the growth and spread of various cancer cell types.
- Reduced rheumatoid arthritis symptoms. Due to anti-inflammatory effects, limited research suggests black seed oil may lessen joint inflammation in people with rheumatoid arthritis.
- Male fertility. Small studies suggest black seed oil might improve semen quality in men diagnosed with infertility.
- Antifungal effects. Black seed oil has demonstrated antifungal activity, including potential protection against Candida albicans, the yeast behind candidiasis.
Although preliminary findings are encouraging, more human research is required to verify these benefits and clarify optimal dosing.
summaryBlack seed oil is rich in antioxidants and may offer several health benefits, including support for asthma, certain skin conditions, lowering blood sugar and cholesterol, aiding weight loss, and protecting brain health.
Potential side effects and safety considerations
When used sparingly in cooking, black seed oil is likely safe for most people.
However, research on the long-term safety of larger, therapeutic doses is limited.
Short-term use (3 months or less) has generally not been associated with serious adverse effects. That said, one study reported nausea and bloating in some participants who took 1 teaspoon (5 mL) of black seed oil daily for 8 weeks.
One concern is potential interactions with drugs metabolized by the cytochrome P450 system. Medications that could be affected include warfarin (Coumadin) and beta-blockers such as metoprolol (Lopressor).
There are case reports suggesting excessive intake might harm the kidneys. For example, a woman with type 2 diabetes was hospitalized with acute kidney failure after taking 2–2.5 grams of black seed capsules daily for 6 days.
Conversely, other studies have not found detrimental kidney effects and some even suggest black seed oil may protect kidney function.
If you have existing kidney disease, consult your healthcare provider before using black seed oil.
Finally, because evidence is limited, pregnant or breastfeeding women should avoid medicinal doses of black seed oil, though small amounts used as a culinary flavoring are likely acceptable.
Overall, more research is required to determine the safety of black seed oil in humans, particularly with long-term use.
SummaryUsing black seed oil in cooking is probably safe for most people. Long-term safety of higher, medicinal doses remains uncertain due to limited research.
How to use black seed oil
Black seed oil is available as capsules or as a liquid for oral use, and can also be applied externally to skin and hair.
If you buy the liquid form, select a high-quality product without added ingredients.
Because supplements are not regulated by the Food and Drug Administration (FDA) for safety and efficacy, choosing a reputable brand is important.
Look for products tested or certified by organizations such as ConsumerLabs, the U.S. Pharmacopeial Convention, or NSF International, which verify quality.
Black seed oil has a bold taste that is slightly bitter and spicy, often compared to cumin or oregano. If taking the liquid oil, you might mix it with a strongly flavored ingredient like honey or lemon juice to improve palatability.
For topical use, the oil may be massaged into the skin.
summaryBlack seed oil can be taken in capsule or liquid form. Because of its strong flavor, mixing the liquid with honey or lemon juice can make it easier to ingest.
Dosage guidance
Although black seed oil may have health benefits, it should not replace prescribed medications.
There is currently inadequate evidence to set a standard recommended dose, so consult your healthcare provider before starting it.
Studied amounts vary depending on the intended use.
For instance, in people with asthma, 1000 mg of black seed oil capsules daily for 4 months was found to be safe and beneficial as an adjunct therapy.
Conversely, for weight loss and blood sugar reduction, studies often used higher intakes of 2–3 grams per day for 8–12 weeks (19, , , ).
Because dosing varies by application, speak with your healthcare provider for individualized recommendations.
summaryThere is no universally accepted dose for black seed oil due to insufficient evidence. Discuss dosing with your healthcare provider to determine an appropriate amount.
The bottom line
Black seed oil is a widely used alternative remedy touted for treating various conditions.
Current evidence suggests it may be helpful for asthma management, supporting weight-loss efforts, and lowering blood sugar and cholesterol.
The antioxidant and anti-inflammatory properties of thymoquinone in black seed oil may also offer neuroprotective effects and slow cancer cell growth.
However, more research is necessary to establish long-term safety and confirm effectiveness.
Before trying black seed oil, consult your healthcare provider to determine whether it’s appropriate for you and what dose to take.
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