Black Seed by North American Herb & Spice

POSSIBLY EFFECTIVE

• Acne. Topical black seed extract hydrogel seems to improve acne. Details: In patients with mild to moderate acne, clinical research shows that topical application with a hydrogel containing black seed extract 0.1% twice daily for 60 days reduces the number of comedones, papules, and pupules by a large amount when compared with placebo. The overall improvement, as rated by a physician, was 78% for the black seed extract hydrogel, compared with 3% for the placebo gel (101551).
• Allergic rhinitis (hay fever). Oral black seed oil seems to reduce symptoms of allergic rhinitis over 4-8 weeks. It is unclear if black seed is beneficial long-term. Details: Clinical research shows that taking capsules containing black seed oil 0.5 mL daily for 1 month can reduce symptoms such as itching, nasal congestion, sneezing, and runny nose when compared with placebo in adults with allergic rhinitis (95989). Other preliminary clinical research shows that taking a specific product containing black seed oil 500 mg (Immerfit, Phyt-Immun) for a total dose of 40-80 mg/kg orally daily for 4-8 weeks improves patient-scored symptoms of allergic rhinitis in 81% of patients, compared to 45% of patients taking placebo (36071). More research is needed to determine if black seed is beneficial long-term and how it compares to conventional allergy medications.
• Asthma. Oral black seed seems to be beneficial for symptoms like wheezing and coughing and might improve lung function measures in patients with poor pulmonary function. Details: Some clinical research shows that taking black seed extract for 3 months can improve symptoms such as wheezing and coughing when compared with placebo in patients with moderate to severe asthma who already take conventional asthma medication (36175). Other research shows that taking black seed oil (Cuminmar, Marnys) 500 mg twice daily for 4 weeks can improve self-reported asthma control and daily functioning when compared with placebo in adults with inadequately controlled asthma despite using maintenance inhalers (95987). The effects of black seed on pulmonary function are conflicting. Some research shows that taking black seed can improve lung function measures such as forced expiratory flow (36175,36280,94490,101556), while other research shows no significant benefit (95987,101556). Doses used in studies showing benefit include ground black seed 2 grams daily for 12 weeks, black seed extract 15 mL/kg daily for 3 months, or a single dose of 50-100 mg/kg (36175,36280,94490). Differing findings may relate to pulmonary function at baseline. Taking black seed extract or black seed oil seems to improve pulmonary function in patients with abnormally low pulmonary function at baseline, but not those with predicted forced expiratory volume in 1 second (FEV1) of at least 80% (36175,95987). Also, single doses of black seed extract do not appear to improve pulmonary function as effectively as bronchodilators such as theophylline or salbutamol (36280).
• Chronic obstructive pulmonary disease (COPD). Oral black seed seems to improve lung function measures in patients with COPD using inhaled corticosteroids. Details: In middle-aged adults undergoing routine treatment with inhaled corticosteroids for COPD, clinical research shows that taking black seed oil (Amazing Herbs) 1 gram twice daily for 3 months improves pulmonary function tests by a small to moderate amount when compared with placebo (104663).
• Diabetes. Oral black seed powder in doses of at least 2 grams daily or black seed oil 1 gram daily seem to improve glucose control in patients with type 2 diabetes. Details: A meta-analysis of 4 clinical studies shows that black seed reduces glycated hemoglobin (HbA1c) by 0.4%. However, analysis of 7 clinical studies suggests that black seed does not reduce fasting blood glucose (111503). One clinical study shows that taking black seed powder 1 gram twice daily for 3-12 months improves HbA1c and decreases fasting blood glucose by 17% to 26% when compared to baseline in patients with diabetes who are already using antidiabetes medications (94479,94485). These improvements were significant when compared with placebo at 3 months and 9 months, but not at 12 months (94485). Clinical research also shows that taking black seed powder 1 gram twice daily also improves levels of total cholesterol by 10% to 12% when compared with placebo in patients with diabetes (94478); a lower dose of 1 gram daily does not seem to be beneficial (94479). The effect of black seed oil has also been investigated. Clinical research shows that taking black seed oil 450 mg three times daily for 12 weeks decreases fasting blood glucose by around 14 mg/dL and HbA1c by 0.3% in patients with newly diagnosed diabetes when compared with baseline. However, these improvements were inferior to those reported in patients taking metformin 2000 mg daily (102062). Other clinical research shows that taking black seed oil 1 gram daily for 8 weeks decreases fasting blood glucose by 23.0 mg/dL and HbA1c by 0.69% from baseline. These changes, as well as reductions in low-density lipoprotein (LDL) cholesterol, triglycerides, and systolic and diastolic blood pressure were significant when compared with placebo (110269). Other clinical research also shows that taking black seed oil 1 gram daily for 8 weeks reduces fasting blood glucose, triglyceride, and low-density lipoprotein (LDL) cholesterol levels when compared with placebo. However, baseline levels for each of these parameters were higher in the treatment group when compared with the placebo group, raising concerns about the validity of these findings (101552). The black seed constituent thymoquinone has also been investigated in clinical research. Clinical research in patients with type 2 diabetes shows that taking thymoquinone 50 mg or 100 mg daily in addition to metformin 1 gram daily for 90 days increases the number of patients with HbA1c levels of less than 7.0% when compared with metformin alone. However, it is unclear if fasting blood glucose levels are further reduced (110270). Black seed has also been evaluated in combination with other ingredients. A moderate-sized clinical study in treatment-naïve adults newly diagnosed with type 2 diabetes shows that taking a combination product containing extracts of black seed 250 mg, cassia cinnamon, and ficin (NW Low-Glu) 4-5 times daily for 12 weeks reduces HbA1c by 0.6-0.8% and 2-hour postprandial glucose by 25-35 mg/dL when compared to baseline and is similarly effective to metformin. However, there were no notable improvements in fasting blood glucose, insulin resistance, or beta cell function (111710). It is unclear if these effects are due to black seed, other ingredients, or the combination.
• Helicobacter pylori. Oral black seed 2 grams daily seems to improve H. pylori eradication when used in combination with standard therapies. Details: Clinical research shows that in patients receiving quadruple therapy with metronidazole, amoxicillin, bismuth subcitrate, and omeprazole, the eradication of H. pylori occurred in 88% of patients receiving quadruple therapy plus black seed powder 1 gram twice daily for 8 weeks, compared with 55% of patients taking quadruple therapy alone. Quality of life was also improved (101555). Clinical research also shows that taking black seed powder (BioExtract Ltd) 2 grams daily along with omeprazole 40 mg daily for 4 weeks produces H. pylori eradication in 67% of patients, compared to 83% of patients taking standard triple therapy with clarithromycin, amoxicillin, and omeprazole taken for 1 week. However, this study also found that taking black seed powder 1 gram or 3 grams daily along with omeprazole was less effective than standard triple therapy (95980). The reasons for this discrepancy are unclear.
• Hyperlipidemia. Oral black seed seems to modestly improve serum lipids in patients with or without hyperlipidemia. Details: A meta-analysis of 24 moderate-quality, clinical studies in healthy adults and patients with various cardiometabolic conditions shows that taking black seed modestly reduces total cholesterol, LDL cholesterol, and triglycerides, and increases HDL cholesterol when compared with placebo or control (114813). Interpretation of findings is limited by significant heterogeneity in results which may be due to the inclusion of different patient populations, doses or types of black seed preparations, and treatment durations. Similarly, a meta-analysis of 5 clinical studies in adults with type 2 diabetes with or without hyperlipidemia shows that taking black seed reduces total cholesterol by 17 mg/dL, low-density lipoprotein (LDL) cholesterol by 11 mg/dL, and triglycerides by 12 mg/dL, but does not improve high-density (HDL) lipoprotein cholesterol, when compared with a control (111503). Additionally, some preliminary clinical research shows that taking whole crushed black seed 1 gram twice daily or black seed powder 1 gram daily for 4-8 weeks reduces total cholesterol by 5% to 16%, LDL cholesterol by 8% to 27%, and triglycerides by 17% to 22% when compared to baseline in these patients; these improvements are significantly greater than changes in the placebo group (18221,94484). The effect of black seed when used in combination with statins shows conflicting results. One clinical study shows that taking black seed powder 1 gram twice daily for 6 weeks does not decrease cholesterol levels when compared with statins alone in normocholesterolemic, borderline hypercholesterolemic, or hypercholesterolemic patients (36244). Other clinical research in adults with hypercholesterolemia shows that taking whole crushed black seed 500 mg, garlic oil 250 mg, and simvastatin 10 mg daily for 8 weeks produces a larger increase in HDL cholesterol and a greater reduction in total cholesterol, LDL cholesterol, and triglycerides when compared with simvastatin 10 mg daily alone (95985). Reasons for these conflicting results may relate to the black seed dose or formulation and the cholesterol levels of the included patients at baseline. Taking whole crushed black seed 1 gram twice daily for 8 weeks in conjunction with aerobic training does not appear to improve LDL cholesterol, total cholesterol, or triglyceride levels when compared with aerobic training alone in females with hypercholesterolemia; however, it appears to modestly increase HDL cholesterol levels (95983).
• Hypertension. Oral black seed powder and black seed oil seem to reduce blood pressure by a small amount. However, if it is unclear if taking black seed is beneficial in patients with hypertension. Details: Meta-analyses of results from 33 small clinical studies in patients with or without hypertension show that taking black seed powder 0.5-3 grams daily or black seed oil 0.1-4.2 grams daily for 4-16 weeks reduces both systolic and diastolic blood pressure by about 2-3 mmHg when compared with placebo (16437,94489,112242). Subgroup analysis suggests that black seed supplementation is most beneficial for durations of 8 weeks or less and in patients over 50 years old with a BMI of 25-30 kg/m2 (112242). Another study in the analysis that included patients with or without hypertension found that taking black seed oil 2.5 mL twice daily after meals for 8 weeks reduces systolic and diastolic blood pressure by about 11 mmHg and 10 mmHg, respectively, when compared to baseline (96929).
• Mastalgia. Topical black seed oil seems to reduce breast pain. Details: Clinical research shows that applying 2 grams of gel containing 30% black seed oil at the site of pain twice daily for two menstrual cycles reduces breast pain by about 82% when compared to baseline. This improvement is similar to diclofenac gel and significantly greater than placebo gel, which reduces pain by only 18% (94483).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Anthracycline cardiotoxicity. It is unclear if oral black seed oil reduces cardiac toxicity associated with doxorubicin treatment. Details: Preliminary clinical research in children aged 2-16 years with acute lymphoblastic leukemia shows that taking black seed oil 80 mg/kg in three divided doses daily for one week, starting with each doxorubicin infusion therapy, is protective against some, but not most, measures of cardiac toxicity associated with doxorubicin. However, it is unclear if any of these changes are associated with clinically meaningful improvements in outcome (101554).
• Atopic dermatitis (eczema). It is unclear if oral or topical black seed oil is beneficial for reducing symptoms of atopic dermatitis. Details: One small study reports that using 15% black seed oil ointment topically for 4 weeks does not improve disease severity, pruritus, or hydration in patients with atopic dermatitis (36316). Other preliminary clinical research shows that taking a specific product containing black seed oil 500 mg (Immerfit, Phyt-Immun) for a total dose of 40-80 mg/kg daily for 4-8 weeks improves subjective patient-scored symptoms of atopic dermatitis in 50% of patients when compared to baseline (36071).
• Autoimmune thyroiditis. It is unclear if oral black seed is beneficial for patients with autoimmune thyroiditis. Details: Clinical research in patients with Hashimoto's thyroiditis shows that taking black seed powder 2 grams daily for 8 weeks increases thyroid stimulating hormone levels by 36% and anti-thyroid peroxidase (anti-TPO) antibody levels by 50% when compared to baseline; these improvements are significant when compared with placebo. However, black seed powder does not improve thyroxine or triiodothyronine levels when compared with placebo (94481).
• Cancer. Although there is interest in using oral black seed for cancer, there is insufficient reliable information about the clinical effects of black seed for this condition.
• Cardiovascular disease (CVD). It is unclear if oral black seed is beneficial for patients with coronary artery disease. Details: A small clinical trial shows that taking black seed oil 2 grams daily for 8 weeks reduces systolic and diastolic blood pressure by 9.52 mm Hg and 8.26 mm Hg, respectively, when compared with placebo. Fasting blood glucose, body mass index, and waist and hip circumferences were also modestly reduced. There was no effect on other glycemic indices. There was also no effect on blood lipids; however, most patients were taking statins (110276).
• Chemotherapy-induced lymphocytopenia. It is unclear if oral black seed is beneficial for preventing febrile neutropenia. Details: Preliminary clinical research in children undergoing chemotherapy for brain tumors shows that taking whole or ground black seed 5 grams daily as part of the diet for 3-9 months of chemotherapy reduces the incidence of febrile neutropenia episodes by 88% when compared with placebo. To prevent one case of febrile neutropenia, six patients would need to be treated with black seed. The duration of hospital stay was also reduced by 2.5 days when compared with placebo (96931).
• Chemotherapy-induced phlebitis. It is unclear if oral black seed is beneficial for reducing the severity of phlebitis in patients receiving intravenous chemotherapy. Details: Preliminary clinical research in cancer patients receiving intravenous chemotherapy shows that applying 5 drops of black seed oil around the peripheral vein catheter twice daily for 3 days decreases phlebitis severity and reduces the relative risk of phlebitis at 72 hours by 35% when compared with no treatment. These results suggest that for every 3 patients treated with black seed oil for 3 days, one additional case of phlebitis will be prevented (102060).
• Chronic kidney disease (CKD). It is unclear if oral black seed oil is beneficial for patients with CKD. Details: Preliminary clinical research in patients with stages 3 and 4 CKD shows that taking black seed oil (Kalonji oil, Mohammedia products) 2.5 mL once daily for 12 weeks as add-on therapy with alpha-keto analogues of essential amino acids improves measures of kidney function by a small amount when compared with taking the alpha-keto analogues alone (101550).
• Cognitive function. Oral black seed might improve some measures of memory or cognitive function. Details: Clinical research in a small group of adolescent males shows that taking crushed black seed 500 mg daily for 4 weeks improves some measures of short-term or long-term recall when compared with placebo (96915). Other clinical research in a small group of middle-aged men shows that taking black seed 500 mg twice daily for 9 weeks improves some measures of memory, attention, and cognitive function when compared with placebo (96928). The improvements in both studies appear to be modest, so the clinical significance is unclear.
• Constipation. Although there is interest in using oral black seed for constipation, there is insufficient reliable information about the clinical effects of black seed for this condition.
• Contraception. Although there is interest in using oral black seed for contraception, there is insufficient reliable information about the clinical effects of black seed for this purpose.
• Coronavirus disease 2019 (COVID-19). It is unclear if oral black seed is beneficial for patients with COVID-19. Details: Preliminary clinical research in patients with mild COVID-19 shows that taking black seed oil (Marnys Cuminmar) 500 mg twice daily for 10 days results in recovery by day 14, defined as freedom of symptoms lasting three days, in 62% of patients, compared with 36% of those patients not given black seed oil. Also, the duration to recovery was reduced by 1.6 days (110267). Preliminary clinical research in patients with mild to moderate COVID-19 shows that taking black seed (Baraka, Pharco Pharmaceuticals, Cairo, Egypt) 900 mg twice daily for 14 days modestly reduces the severity of some symptoms, including cough, diarrhea, fatigue, and pharyngitis, as well as the percentage of patients with viral positivity at day 7, when compared with standard care alone. Similar findings occurred when black seed was taken with vitamin D3 (Davalindi, Medical Union Pharma, Cairo, Egypt) 2,000 IU daily (110265). These studies are limited by a lack of placebo and blinding. A meta-analysis of 3 studies in patients with COVID-19 shows that taking black seed 40-80 mg/kg for 13-14 days or 500 mg twice daily for 7 days reduces the odds of mortality by 78% relative to patients with COVID-19 who did not use black seed (112243). In contrast to these findings, clinical research in patients with mild or asymptomatic COVID-19 does not show that taking black seed for 10 days has beneficial effects on symptoms or inflammatory markers when compared with charcoal as control. The black seed form in this study varied between whole seeds and powder, as well as the number (two to nine) of capsules taken in divided doses daily (110271). Black seed oil has also been investigated in combination with other compounds. Preliminary clinical research in patients with moderate to severe COVID-19 given standard care shows that taking black seed powder 80 mg/kg daily in combination with raw honey 1 gram/kg daily for 13 days reduces the time to alleviate symptoms by approximately 50%, and the time to clear virus by about 35%, when compared with placebo capsules and no honey. In patients with moderate symptoms, 63.6% had resumed normal activity within 6 days when compared with 10.9% of those taking placebo. In patients with severe symptoms, 50% were discharged from hospital by day 6 compared with 2.8% of those taking placebo, and the mortality rate was reduced by approximately 79% (110261). It is not clear if any beneficial effects are due to black seed, honey, or the combination.
• Diarrhea. Although there is interest in using oral black seed for diarrhea, there is insufficient reliable information about the clinical effects of black seed for this condition.
• Dysmenorrhea. It is unclear if topical black seed oil reduces menstrual pain. Details: Clinical research shows that topical application of black seed oil (Barij Essence Company) 1-2 drops to the fontanel lobe of the head each night for up to 8 days, starting three days before menstruation, for three menstrual cycles modestly reduces menstrual pain when compared with olive oil (104662). It is unclear if any benefits are clinically significant.
• Dyspepsia. Oral black seed oil has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research shows that taking a 1:1:1 mixture of a black seed oil, honey, and water orally for 2 months improves overall symptoms of dyspepsia by approximately 43%, compared to only 10% in the placebo group (94487).
• Epilepsy. It is unclear if oral black seed is beneficial for patients with epilepsy. Details: Some preliminary clinical research in children aged 13 months to 13 years with epilepsy shows that taking black seed extract 40 mg/kg every 8 hours for 4 weeks reduces the frequency of seizures in 65% of, compared to only 20% of patients taking placebo (36180). Other preliminary clinical research in children 2-16 years of age with epilepsy shows that taking black seed oil 40-80 mg/kg daily does not reduce seizure frequency or severity when compared with placebo (94491). It is possible that there is a constituent found in the extract, and absent in the oil, that is responsible for any anti-seizure effects of black seed.
• Gingivitis. It is unclear if topical black seed is beneficial for patients with gingivitis. Details: In patients with moderate to severe gingivitis, preliminary clinical research shows that topical application of black seed extract for three days reduces gingival swelling and redness by a moderate amount, and plaque by a small amount, when compared to baseline. However, it is less effective than scaling and root planing (104664).
• Hemorrhoids. Although there is interest in using oral black seed for hemorrhoids, there is insufficient reliable information about the clinical effects of black seed for this condition.
• Hepatitis C. It is unclear if oral black seed is beneficial for patients with hepatitis C. Details: Preliminary clinical research shows that taking black seed oil (Baraka, Pharco Pharmaceuticals) 450 mg three times daily for 3 months reduces hepatitis C viral load in 67% of patients, improves lower limb edema, and modestly increases total protein and albumin levels when compared to baseline; however, no improvement is seen in Child-Pugh score or other measures of liver function, including bilirubin, liver enzymes, or INR (95986). The validity of these findings is limited by the lack of a control group.
• HIV/AIDS. Although there is interest in using oral black seed for HIV/AIDS, there is insufficient reliable information about the clinical effects of black seed for this condition.
• Impaired glucose tolerance (prediabetes). It is unclear if oral black seed oil is beneficial for patients with prediabetes. Details: Preliminary clinical research in obese patients with prediabetes shows that taking black seed oil (Baraka450; Pharco Pharmaceutical Company) 450 mg twice daily for 6 months improves most anthropometric, lipid, and glycemic parameters when compared with baseline. Also, most improvements are similar to changes following the use of metformin 500 mg twice daily or following a controlled diet and exercise regimen (110275).
• Influenza. Although there is interest in using oral black seed for influenza, there is insufficient reliable information about the clinical effects of black seed for this condition.
• Insomnia. It is unclear if oral black seed oil is beneficial for patients with insomnia. Details: A small clinical study in healthy adults with self-reported sleep problems shows that taking a specific black seed oil extract product containing 5% thymoquinone (BlaQmax, Akay Natural Ingredients) 200 mg daily before bedtime for 90 days increases sleep quality, latency, duration, and efficiency and reduces sleep disturbances and daytime dysfunction when compared with placebo. Black seed oil also improves biomarkers of sleep as shown by increased salivary melatonin and decreased orexin A (112244).
• Lichen planus. It is unclear if topical black seed oil is beneficial for patients with oral lichen planus. Details: Clinical research in patients with oral lichen planus shows that topical application with cream containing black seed oil (Greenish Baraka black seed oil, Greenish India Pvt. Ltd., Chennai) 75% twice daily after meals for 45 days is as effective as gel containing clobetasol propionate 0.05% for reducing lesion size and burning severity (110263). Similarly, a very small, open-label, non-randomized intervention in patients with oral lichen planus shows that topical application of a mucoadhesive patch containing black seed extract 10% three times daily for 4 weeks is as effective as a triamcinolone acetonide 0.1% patch for reducing pain and burning intensity and lesion severity (114815). Both studies are limited by the lack of inclusion of a placebo-controlled group.
• Male infertility. It is unclear if oral black seed oil is beneficial for male infertility. Details: Clinical research shows that taking black seed oil 2.5 mL twice daily for 2 months improves sperm count by 40%, sperm morphology by 32%, and sperm motility by 13% when compared with placebo in infertile males (94486).
• Meniere disease. It is unclear if oral black seed is beneficial for patients with Meniere disease. Details: A very small clinical study in adults with Meniere disease shows that taking black seed oil 1 gram daily for 3 months does not improve hearing threshold, tinnitus severity, or vertigo when compared with placebo (112245).
• Menopausal symptoms. Oral black seed has only been evaluated in combination with other ingredients; its effect when used alone is unclear. It is unclear if topical black seed oil is beneficial for menopausal symptoms. Details: Preliminary clinical research in postmenopausal females shows that taking a combination of black seed and vitex agnus-castus daily for 8 weeks, in combination with citalopram 20 mg, improves vasomotor, psychosocial, and physical symptoms of menopause when compared with placebo and citalopram (100325). It is not clear if these effects are due to black seed, vitex agnus-castus, or the combination. Clinical research in postmenopausal females shows that topical application with 2-3 drops of black seed oil (Barij Essence Pharmaceutical Company, Kashan, Iran) on the lower abdomen twice daily for 8 weeks does not improve sexual function or quality of life related to menopause when compared with placebo (110262).
• Metabolic syndrome. It is unclear if oral black seed is beneficial for patients with metabolic syndrome. Details: Clinical research in patients with metabolic syndrome after menopause shows that taking black seed extract 500 mg daily for 8 weeks improves levels of fasting blood sugar by 23%, low-density lipoprotein (LDL) cholesterol by 12%, and triglycerides by 8% over baseline. These changes were significant when compared with placebo. However, taking black seed extract did not improve anthropometric measures when compared with placebo (101549). In addition, preliminary clinical research in patients with metabolic syndrome shows that taking a specific black seed oil product (Mohammedia Products, Hyderabad) 2.5 mL twice daily for 6 weeks decreases total cholesterol by 59%, LDL cholesterol by 50%, and fasting blood glucose by 58% over placebo (36262). The effects of this black seed oil product on other important parameters of metabolic syndrome, such as weight and blood pressure, were not reported in this study. In contrast, other clinical research shows that taking bread providing black seed powder 3 grams daily for 2 months does not have a significant effect on lipid profiles in patients with metabolic syndrome. Weight and waist circumference were not reported (104667).
• Methotrexate toxicity. It is unclear if oral black seed oil is beneficial for reducing toxicity associated with methotrexate treatment. Details: Preliminary clinical research shows that taking black seed oil (Baraka, Pharco Pharmaceuticals) 80 mg/kg orally in three divided doses daily for 1 week after each methotrexate dose prevents elevations in bilirubin and liver function enzymes when compared with placebo in children aged 4-13 years with acute lymphoblastic leukemia (95984).
• Nonalcoholic fatty liver disease (NAFLD). Research suggests that oral black seed or black seed oil modestly improves some metabolic and liver health parameters in patients with NAFLD. However, some studies are small, and research related to measures of steatosis, including liver biopsy and magnetic resonance imaging (MRI), is needed. Details: Clinical research in adults with NAFLD shows that taking black seed oil 2.5 mL twice daily for 3 months, or 1000 mg (Barij Essence Co., Iran) daily for 8 weeks, modestly increases high-density lipoprotein (HDL) cholesterol levels and reduces levels of liver function enzymes, low-density lipoprotein (LDL) cholesterol, and triglycerides when compared with placebo (100322,110282). These studies also show that taking black seed oil also modestly improves levels of fasting blood glucose (110282) and steatosis grade as measured by ultrasound (100322). In one study, both black seed oil capsule and placebo capsule also contained honey and water (100322). However, taking black seed oil does not seem to improve insulin levels (110282). The effect of black seed oil on blood pressure has also been investigated. Clinical research shows that taking black seed oil (Barij Black Seed Oil, Barij Essence Pharmaceutical Company, Kashan, Iran) 1000 mg daily for 8 weeks does not reduce systolic or diastolic blood pressure when compared with placebo (110274,110282). Black seed has also been investigated in small clinical trials in adults with NAFLD. One trial shows that taking black seed 2 grams daily for 12 weeks reduces glucose and insulin levels, improves measures of insulin sensitivity and resistance, and reduces hepatic steatosis percentage when compared with placebo. However, there was no improvement in fibrosis scores, steatosis grades, and levels of lipids and liver function enzymes (102061). Another trial shows that using the same dose of black seed powder results in large reductions in body weight and body mass index (BMI), as well as liver enzymes, when compared with placebo. Also, 57.1% of patients taking black seed had normal fatty liver grading on abdominal ultrasound, compared with 6% of those taking placebo (110268). The reasons for these disparate results are unclear. However, it is possible the studies were underpowered to detect differences in secondary outcomes. More research is needed using gold standard measures of steatosis, including liver biopsy and magnetic resonance imaging (MRI).
• Obesity. It is unclear if oral black seed is beneficial for increasing weight loss. Details: Meta-analyses of preliminary clinical research show that taking black seed oil 3-5 grams daily, black seed powder 0.1-3 grams daily, or black seed extract 100-200 mg daily for up to 13 weeks reduces body weight by about 2-4 kg and body mass index (BMI) by 0.85-1.2 kg/m2 when compared with placebo. It is unclear if these reductions are clinically significant. In addition, most studies in these meta-analyses do not involve patients with a BMI over 25 kg/m2 (96926,98815,111503). Although some individual research shows that taking black seed powder 2 grams or black seed oil 3 grams daily for 8 weeks does not reduce BMI in overweight females who are also exercising or following a low-calorie diet (95983,96927), most individual studies show that black seed or black seed oil reduces body weight and waist circumference (95730,96927,104661,110269). One study shows that black seed has a moderate effect on weight loss, BMI, and waist circumference, and a small effect on total and visceral fat mass (104661). These studies have used black seed powder 1.5 grams twice daily for 3 months or black seed oil 2 or 3 grams daily for 8 weeks (95730,96927,104661). Reasons for the discrepancies may relate to concomitant use with dieting or exercise. It is unclear if taking black seed oil improves the lipid profile of individuals with a BMI of at least 25 kg/m2. One small clinical study shows that taking black seed oil 2 grams daily for 8 weeks has a small to moderate effect on levels of high-density lipoprotein (HDL) cholesterol and low-density lipoprotein (LDL) cholesterol when compared with placebo (104666). However, another study shows that although taking black seed oil 3 grams daily for 8 weeks reduces triglyceride levels more than placebo, there is no effect on HDL or LDL cholesterol levels (96927).
• Opioid withdrawal. It is unclear if oral black seed is beneficial for reducing symptoms of opioid withdrawal. Details: Preliminary clinical research shows that taking black seed powder 500 mg by mouth three times daily for 12 days decreases symptoms of opioid withdrawal by 70% to 77% when compared to baseline (36239). The validity of this finding is limited by the lack of a comparator group.
• Oral submucous fibrosis. It is unclear if oral black seed is beneficial for oral submucous fibrosis. Details: A small clinical study in patients with oral submucous fibrosis shows that taking black seed 1000 mg 3 times daily for 3 months increases mouth opening by 14%, cheek flexibility by 44%, tongue protrusion by 9%, and reduces burning sensations by 79% when compared to baseline, but not when compared with a combination product containing turmeric and black pepper (114880). The validity of this study is limited by the lack of a placebo group.
• Osteoarthritis. It is unclear if topical black seed oil is beneficial for knee osteoarthritis. Details: Preliminary clinical research shows that applying black seed oil 1 mL to the knee by massaging into the skin for 5 minutes three times daily for 3 weeks reduces pain when compared to baseline and produces a larger reduction in pain than acetaminophen 325 mg three times daily for 3 weeks (95981). Other clinical research shows that applying approximately 10 mL of black seed oil to the knees three times weekly for 1 month reduces pain severity when compared to baseline (98814). The validity of this finding is limited by the lack of a control group.
• Polycystic ovary syndrome (PCOS). It is unclear if oral black seed is beneficial for PCOS. Details: A moderate-sized clinical study in adolescents with PCOS shows that taking black seed 1000 mg daily for 16 weeks reduces ovarian volume, testosterone and luteinizing hormone levels, hirsutism, and menstrual irregularities when compared with oral medroxyprogesterone 10 mg daily on menstrual cycle days 14 to 23 (114814). The validity of this study is limited by poor methodology, including results presented only using a per-protocol analysis.
• Psoriasis. Although there is interest in using topical black seed for psoriasis, there is insufficient reliable information about the clinical effects of black seed for this condition.
• Radiation dermatitis. It is unclear if topical black seed is beneficial for preventing dermatitis caused by radiotherapy. Details: Clinical research in breast cancer patients undergoing radiation treatment shows that applying a gel containing black seed extract providing thymoquinone 0.01% twice daily delays the incidence of radiation dermatitis and the onset of moist desquamation by 2-6 days when compared with placebo gel. However, there was no effect on the quality of life related to skin condition (101557).
• Rheumatoid arthritis (RA). It is unclear if topical black seed is beneficial for RA. Details: Preliminary clinical research shows that taking a specific brand of black seed oil (Nigellar, Kahira Pharmaceutical and Chemical Industries Company) 500 mg twice daily for one month improves symptoms of RA, such as pain, morning stiffness, and disease severity, when compared with placebo in patients who are already taking methotrexate (94482).
• Senile rhinitis. It is unclear if topical black seed is beneficial for patients with senile rhinitis. Details: The elderly population is particularly susceptible to symptoms of nasal dryness and irritation due to a reduction in mucus production. Preliminary clinical research shows that black seed oil given as 3 sprays into each nostril three times daily for 2 weeks can modestly improve symptoms of nasal dryness, obstruction, and crusting in this population when compared with sodium chloride nasal spray; however, there is no improvement in burning, itching, or nasal mucociliary clearance (95988).
• Stress. It is unclear if oral black seed is beneficial for patients with stress. Details: A small clinical study in healthy adults with self-reported stress shows that taking a specific black seed oil extract product containing 5% thymoquinone (BlaQmax, Akay Natural Ingredients) 200 mg daily before bedtime for 90 days reduces measures of perceived stress and salivary cortisol levels when compared with placebo (112244).
• Tonsillopharyngitis. Oral black seed has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that the combination of chanca piedra 50 mg and black seed 360 mg, taken orally three times daily for 7 days, may relieve pain in patients with tonsillopharyngitis when compared with placebo (36199).
• Ulcerative colitis. It is unclear if oral black seed is beneficial for patients with ulcerative colitis. Details: Preliminary clinical research in adults with mild to moderate ulcerative colitis shows that taking black seed powder 2000 mg daily for 6 weeks does not improve disease activity scores or symptoms of ulcerative colitis when compared with placebo (100323).
• Urinary incontinence. It is unclear if topical black seed oil is beneficial for patients with urinary incontinence. Details: Clinical research in postmenopausal females with urinary incontinence shows that topical application with 2-3 drops of black seed oil (Barij Essence Pharmaceutical Company, Kashan, Iran) on the lower abdomen twice daily for 8 weeks modestly improves symptoms of mixed urinary incontinence, as well as related quality of life, when compared to placebo. However, there was no beneficial effect of topical black seed oil on stress incontinence, urge incontinence, or severity of symptoms (110262).
• Vaginal candidiasis. Although there is interest in using intravaginal black seed for vaginal fungal infections, there is insufficient reliable information about the clinical effects of black seed for this condition.
• Vitiligo. It is unclear if topical black seed oil is beneficial for patients with vitiligo. Details: Preliminary clinical research in adults with vitiligo shows that applying a cream containing black seed oil to the skin twice daily for 6 months improves skin pigmentation. This cream induced repigmentation of 50% or more in around 44% of patients with facial or hand involvement and 88% of patients with genital region involvement (102064). The validity of these findings is limited by the lack of a comparator group. More evidence is needed to rate black seed for these uses.

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INSUFFICIENT RELIABLE EVIDENCE to RATE

• Dyspepsia. Oral olive leaf extract has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small study in healthy adults shows that taking a specific combination product containing olive leaf extract 24% and prickly pear cactus 33% (Mucosave, Bionap S.R.L.) 400 mg daily for 8 weeks seems to improve dyspepsia and other gastrointestinal symptoms when compared with placebo (105904). It is unclear if this benefit would occur in patients with clinically diagnosed dyspepsia.
• Exercise-induced respiratory infections. It is unclear if oral olive leaf extract is beneficial for reducing respiratory infections from exercise. Details: A small clinical study in high school athletes shows that taking one tablet of olive leaf extract providing eleuropein 100 mg daily for 2 months during training season does not reduce the incidence of the common cold when compared with placebo. While it may reduce the number of sick days by 28%, a sub-group analysis suggests that this reduction is only evident in female athletes (101860).
• Gastroesophageal reflux disease (GERD). Although there is interest in using oral olive leaf for GERD, there is insufficient reliable information about the clinical effects of olive for this condition.
• Herpes zoster (shingles). Although there is interest in using oral olive leaf for shingles, there is insufficient reliable information about the clinical effects of olive for this condition.
• Influenza. Although there is interest in using oral olive leaf for influenza, there is insufficient reliable information about the clinical effects of olive for this condition.
• Metabolic syndrome. It is unclear if oral olive leaf extract is beneficial for improving body composition and cardiovascular risk factors in patients with metabolic syndrome. Details: A small clinical trial in overweight, middle-aged males at risk for metabolic syndrome shows that taking four capsules of olive leaf extract providing oleuropein 51.1 mg and hydroxytyrosol 9.7 mg daily for 12 weeks improves insulin sensitivity by 15% when compared with placebo. However, body composition, blood pressure, cholesterol levels, and other cardiovascular risk factors were not improved (92245).
• Osteoarthritis. It is unclear if oral olive fruit or leaf extract is beneficial for improving osteoarthritis. Details: Preliminary clinical research shows that taking a freeze-dried aqueous extract of olive fruit 400 mg daily for 8 weeks decreases pain and increases mobility in people with osteoarthritis (14844). Other preliminary clinical research in adults with knee osteoarthritis shows that taking olive leaf extract 50.1 mg daily for 4 weeks improves overall pain measurements by 14%, compared to only 4% in the placebo group. However, many individual measurements of pain are not improved (92252).
• Osteoporosis. It is unclear if oral olive leaf extract is beneficial for osteoporosis. Details: Clinical research shows that taking olive leaf extract (Bonolive, BioActor BV) 250 mg daily for 12 months, along with elemental calcium 400 mg daily, increases osteocalcin levels by about 32% when compared to baseline; this increase was significant when compared to those taking calcium 400 mg plus placebo, who showed a 6% decrease in osteocalcin levels. However, taking olive leaf extract does not significantly increase bone mineral density of the lumbar spine or femur neck when compared with placebo (92247).
• Rheumatoid arthritis (RA). It is unclear if oral olive fruit extract is beneficial for improving RA symptoms. Details: Preliminary clinical research in adults with RA shows that taking an aqueous freeze-dried extract of olive fruit 400 mg daily for 8 weeks does not improve symptoms when compared with control (14844). More evidence is needed to rate the effectiveness of olive for these uses.

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POSSIBLY INEFFECTIVE

• Cardiovascular disease (CVD). Most research suggests that increasing dietary intake of omega-6 fatty acids does not reduce the risk of CVD. Details: A meta-analysis including 19 low-quality randomized controlled trials that followed patients for 1-8 years shows that higher intake of omega-6 fatty acids for at least 12 months does not reduce the risk of primary or secondary CVD events, coronary heart disease (CHD) events, stroke, or all-cause or CVD mortality when compared with a lower intake. The intake of omega-6 fatty acids ranged from 0.8% to 20.6% of energy (99973). Population research conducted over about 7.3 years has also found that baseline red blood cell omega-6 fatty acid levels are not associated with CVD events, CHD events, ischemic strokes, CVD deaths, or all-cause mortality (99974), and red blood cell omega-6 fatty acid levels do not differ between people with or without coronary artery disease in patients hospitalized for coronary angiography (96918). However, some research suggests that individual omega-6 fatty acids may have differing effects in the body. One population study has found that increased levels of shorter chain omega-6 fatty acids in red blood cells, including linoleic acid, gamma linolenic acid, and dihomo-gamma linolenic acid, are associated with a reduced risk of CVD mortality. Higher levels of the longer chain omega-6 fatty acids adrenic acid and docosapentaenoic acid are associated with a moderately increased risk of overall mortality in these patients (96918). Higher quality studies are needed to confirm these findings.
• Child development. Most research suggests that supplementing infant formula with arachidonic acid, an omega-6 fatty acid, and docosahexaenoic acid (DHA), an omega-3 fatty acid, does not improve infant or child development. Details: Meta-analyses of clinical research show that inclusion of arachidonic acid in infant formula at levels of up to 0.84% of fatty acids, in addition to DHA, for 2-12 months does not improve visual or neurodevelopmental outcomes in preterm or full-term infants up to 18 months of age (96919,96920). Also, giving infants DHA- and arachidonic acid-supplemented formula during infancy does not appear to improve neurodevelopment by the age of 6 years (92503).
• Hyperlipidemia. Increasing dietary intake of omega-6 fatty acids does not seem to lower plasma cholesterol or triglyceride levels. Details: A meta-analysis of clinical research shows that increasing intake of omega-6 fatty acids, specifically linoleic acid or gamma-linolenic acid, by replacing dietary saturated or monounsaturated fatty acids modestly reduces levels of total cholesterol. However, the clinical significance is unclear. Also, increasing intake of omega-6 fatty acids does not seem to affect levels of high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, or triglycerides (99973).
• Multiple sclerosis (MS). Most research suggests that taking omega-6 fatty acids is not beneficial for MS. Details: A meta-analysis of the available literature shows that taking omega-6 fatty acids, mainly as linoleic acid, does not seem to prevent disease progression in relapsing-remitting MS patients or chronic progressive MS patients at 24 months (107318).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Age-related cognitive decline. It is unclear if increased dietary omega-6 fatty acid intake is beneficial for preventing age-related cognitive decline. Details: Population research has found that the highest blood levels of omega-6 fatty acids during middle age are associated with the best overall cognitive functioning 13 years later when compared with lower intakes (99979). In addition, the highest tertile of omega-6 fatty acid intake in older adults, at least 8.8 mg per kcal daily, is inversely associated with having low cognitive performance. However, the same pattern was observed for the highest tertile of omega-3 fatty acids, and the omega-6 to omega-3 fatty acid ratio in the diet had no overall association with cognitive performance (103308).
• Attention deficit-hyperactivity disorder (ADHD). Oral omega-6 fatty acids have only been evaluated in combination with other ingredients; their effect when used alone is unclear. Details: Preliminary clinical research shows that taking a combination of omega-3 and omega-6 fatty acids twice daily for 3-6 months does not improve symptoms of ADHD in most children when compared with placebo, although it may improve ADHD symptoms in a subgroup of children with ADHD inattentive subtype plus comorbid neurodevelopmental disorders (65864).
• Blepharitis. It is unclear if oral omega-6 fatty acids are beneficial for blepharitis. Details: One preliminary clinical study in patients with Meibomian gland dysfunction shows that taking a specific product (Medilar, Fidia Oftal Bausch & Lomb Pharmaceuticals), which contains the omega-6 fatty acids linoleic acid 28.5 mg and gamma-linolenic acid 15 mg, once daily for 180 days in combination with eyelid hygiene can improve cloudiness from eye secretions and gland obstruction when compared with baseline (66665). However, the lack of a control group limits the validity of these results. Population research involving postmenopausal adults has also found that moderate dietary intake of omega-6 fatty acids is associated with a reduced risk of developing Meibomian gland dysfunction. However, high intake was not associated with a reduced risk in these patients, and the protective effect of omega-6 fatty acids, if any, in the general population is unclear (99978). Higher quality research is needed to confirm these results.
• Cancer. It is unclear if increased dietary intake of omega-6 fatty acids is beneficial for cancer prevention. Details: In a meta-analysis of clinical research, increasing intake of dietary omega-6 fatty acids does not seem to reduce cancer risk or mortality. However, the included research is of low quality (107005). Also, a meta-analysis of population research has found that dietary intake of omega-6 fatty acids is not associated with cancer risk. However, high blood levels of omega-6 fatty acids were associated with an 8% reduced risk of cancer when compared to low blood levels, with breast cancer carrying the strongest association. Each 5% increase in blood levels of omega-6 fatty acids was associated with a 2% decreased cancer risk (107006). These results should be interpreted with caution, since factors other than omega-6 fatty acid intake, such as alcohol intake or overall diet, may affect blood levels of omega-6 fatty acids (100516).
• Developmental coordination disorder (DCD). Oral omega-6 fatty acids have only been evaluated in combination with other ingredients; their effect when used alone is unclear. Details: Preliminary clinical research shows that taking a combination of omega-6 and omega-3 fatty acids for 3 months can improve reading, spelling, and behavior, but not motor skills, when compared with placebo in children with DCD (13748).
• Diabetes. It is unclear if higher dietary or supplemental intake of omega-6 fatty acids is associated with a reduced risk of diabetes. Details: Population research has found that the highest blood levels of the omega-6 fatty acid linoleic acid are associated with a 43% reduced risk of developing diabetes over a period of 5-42 years when compared with the lowest blood levels. Blood levels of another omega-6 fatty acid, arachidonic acid, do not seem to be linked to diabetes risk (96914). These results should be interpreted with caution, since factors other than omega-6 fatty acid intake, such as alcohol intake or overall diet, may affect blood levels of omega-6 fatty acids (100516). In addition, a meta-analysis of low-quality clinical research does not support any benefit of omega-6 fatty acids in the prevention or treatment of type 2 diabetes (101504).
• Diarrhea. It is unclear if formula supplemented with arachidonic acid is beneficial for diarrhea prevention in infancy. Details: Preliminary clinical research shows that infant formula supplemented with arachidonic acid 34 mg/100 kcal and docosahexaenoic (DHA) acid, an omega-3 fatty acid, 17 mg/100 kcal (Enfamil Premium 1 and Enfamil Premium 2, Mead Johnson Nutrition) can reduce the incidence of diarrhea in the first year of life when compared with non-supplemented infant formula (92505).
• Dry eye. It is unclear if dietary intake of omega-6 fatty acids is beneficial for dry eye prevention. Details: Population research has found that higher intake of dietary omega-6 fatty acids is not associated with a reduced risk of dry eye after menopause (99978).
• Hypertension. It is unclear if dietary intake of omega-6 fatty acids is beneficial for blood pressure reduction. Details: Population research has found that higher dietary intake of omega-6 fatty acids, especially linoleic acid, is inversely associated with the odds of hypertension in non-diabetic individuals. However, in patients with diabetes, higher intake of omega-6 fatty acids is associated with an increased odds of hypertension (99975).
• Nonalcoholic fatty liver disease (NAFLD). It is unclear if dietary intake of omega-6 fatty acids is beneficial for NAFLD prevention. Details: Cross-sectional population research is mixed with respect to dietary intake of omega-6 fatty acids in patients with NAFLD when compared with healthy controls. One large cross-sectional study based on data from the National Health and Nutrition Examination Survey (NHANES) between 2007-2014 has found that consuming omega-6 fatty acids at a dose of at least 250 mg/kg daily is associated with an 82% reduced risk of having NAFLD when compared with consuming less than 121.3 mg/kg daily (107002).
• Obesity. It is unclear if oral omega-6 fatty acids are beneficial for reducing cholesterol or triglyceride levels in adults with obesity. Details: In individuals with abdominal obesity, a small clinical trial shows that taking linoleic acid 15 grams (females) or 20 grams (males) (Pharmatech AS) daily for 7 weeks from safflower oil has modest beneficial effects on levels of low-density lipoprotein (LDL)-, high-density lipoprotein (HDL)-, and total cholesterol when compared with baseline or taking fish oil. However, there was no effect on triglyceride levels (107003).
• Photoreactive keratectomy. Oral omega-6 fatty acids have only been evaluated in combination with other ingredients; their effect when used alone is unclear. Details: Preliminary clinical research in patients who have undergone photoreactive keratectomy shows that taking a tablet containing the omega-6 fatty acids linoleic acid and gamma-linolenic acid, as well as beta-carotene, B vitamins, and trace minerals, daily for 30 days can improve tear production and eye healing when compared with a control group (66679).
• Respiratory tract infections. It is unclear if supplementing infant formula with arachidonic acid is beneficial for preventing respiratory tract infections. Details: Preliminary clinical research shows that infant formula supplemented with arachidonic acid 34 mg/100 kcal and docosahexaenoic acid (an omega-3 fatty acid) 17 mg/100 kcal (Enfamil Premium 1 and Enfamil Premium 2, Mead Johnson Nutrition) can reduce the incidence of respiratory illness in the first year of life when compared with non-supplemented infant formula (92505). More evidence is needed to rate omega-6 fatty acids for these uses.

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LIKELY SAFE ...when used orally in amounts found in foods (6).

POSSIBLY SAFE ...when black seed oil is used orally at doses of up to 5 mL or 5 grams daily for up to 12 weeks (36071,94486,96927,96929,98815,101550,102062,110269,110276). ...when a specific black seed oil formulation containing 5% thymoquinone (BlaQmax) is used in doses of 200 mg daily for 90 days (110264). ...when black seed powder is used orally at doses of up to 2 grams daily for up to 12 months (36239,36244,94478,94479,94485,96928,102061,110268,110271) or 3 grams daily for 3 months (114880). ...when used topically and appropriately, short-term. There is some clinical evidence that black seed oil can be safely applied as an oil 2 times daily for up to 6 months or 3 times daily for up to 1 month (95981,98814,102064,110262), as a 30% gel twice daily for approximately 2 months (94483), or as a 10% solution in a patch to oral lesions 3 times daily for 4 weeks (114815).

CHILDREN: POSSIBLY SAFE
when black seed oil is used orally at doses of 40-80 mg/kg daily for 2-19 months in children ages 4-17 years old (36071,95984). However, the higher dose of 80 mg/kg daily has been associated with increased adverse effects such as gastrointestinal complaints when taken on an empty stomach (36071).

PREGNANCY: LIKELY UNSAFE
when used orally in amounts exceeding those found in food. Black seed may decrease or inhibit uterine contractions (241) and may have contraceptive activity (242).

LACTATION:
Insufficient reliable information available; avoid using.

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LIKELY SAFE ...when olive fruit is used orally and appropriately in amounts commonly found in foods.

POSSIBLY SAFE ...when olive leaf extract is used orally and appropriately. Olive leaf extract providing 51-100 mg oleuropein daily has been used with apparent safety for 6-8 weeks (92245,92247,101860). There is insufficient reliable information available about the safety of olive fruit extract when used in amounts greater than those found in foods.

PREGNANCY AND LACTATION:
Insufficient reliable information available; stick with amounts commonly found in foods.

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LIKELY SAFE ...when used orally in amounts found in foods. Dietary intake in amounts of 5% to 10% of daily calories are appropriate according to the Dietary Reference Intake (DRI) Acceptable Macronutrient Distribution Range (AMDR) (23723). There is insufficient reliable information available about the safety of omega-6 fatty acids when used orally in medicinal amounts.

CHILDREN: LIKELY SAFE
when consumed by children over the age of 12 months as part of the diet in amounts between 5% to 10% of daily calories according to the Dietary Reference Intake (DRI) Acceptable Macronutrient Distribution Range (AMDR) (23723).

PREGNANCY AND LACTATION: LIKELY SAFE
when consumed as part of the diet in amounts between 5% and 10% of daily calories according to the Dietary Reference Intake (DRI) Acceptable Macronutrient Distribution Range (AMDR) (23723).

PREGNANCY AND LACTATION: POSSIBLY UNSAFE
when high amounts of omega-6 fatty acids are consumed in the diet. Population research suggests that the highest maternal intakes of omega-6 fatty acids (15.2-47.6 grams or 137-428 kcal daily) during pregnancy is associated with a 2.4-times greater odds of giving birth to an infant below the 10th percentile for birth weight when compared with the lowest maternal intakes (0.4-5.7 grams daily) (96913). In addition, population research in women with a history of atopy suggests that the highest blood levels of omega-6 fatty acids during the second trimester is associated with an increased odds of having a child develop atopic dermatitis by age 4-6 years when compared with the lowest intakes (103309). There is insufficient reliable information available about supplemental omega-6 fatty acids; avoid using.

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ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, black seed may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.  Details In vitro and animal research suggests that black seed extract can inhibit platelet aggregation and clotting, and increase bleeding time (36029,36049,36100,108701). In addition, decreased platelet counts have occurred in a human case report and in animal research (104665).

ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, taking black seed with antidiabetes drugs might increase the risk of hypoglycemia.  Details Some clinical research (36262,94479,94485,101552,102062,110269,110276) and numerous animal studies (36037,36086,36150,36155,36214,110270) suggest that black seed, especially its constituent thymoquinone, can have hypoglycemic effects.

ANTIHYPERTENSIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, taking black seed with antihypertensive drugs might increase the risk of hypotension.  Details Clinical research suggests that black seed powder and oil might reduce blood pressure by 2-3 mmHg (16437,94489). In animal research, black seed modestly reduces blood pressure and concomitant use of black seed and amlodipine (Norvasc) or metoprolol (Lopressor) increased the blood pressure lowering effects of these drugs (101559,108703).

CLOPIDOGREL (Plavix) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, black seed may increase the risk of bleeding if used with clopidogrel.  Details Animal research shows that taking black seed extract daily for 2 weeks prior to a single dose of clopidogrel increases maximum concentrations of clopidogrel by approximately 31% and modestly decreases oral clearance. Furthermore, bleeding time was increased by 12% (108701). This has not been shown in humans.

CNS DEPRESSANTS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use with drugs that have sedative properties may cause additive effects.  Details Animal research suggests that black seed may have CNS depressant effects (36064).

CYCLOSPORINE (Neoral, Sandimmune) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically taking black seed might reduce the levels and clinical effects of cyclosporine.  Details In animal research, black seed extract decreased the maximal levels of cyclosporine in the blood by 35.5% (94474). This has not been shown in humans.

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, black seed might increase levels of drugs metabolized by CYP2C9.  Details In vitro research suggests that thymoquinone, a constituent of black seed, can decrease the metabolism of phenytoin by a mechanism possibly related to the inhibition of CYP2C9 (110281). The effect of black seed on CYP2C9 is unclear. This has not been shown in humans.

DIURETIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking black seed with diuretic drugs might increase potassium loss and the risk of hypokalemia.  Details Black seed extract has shown diuretic effects in animals, which could theoretically increase potassium loss (36026). This has not been shown in humans.

IMMUNOSUPPRESSANTS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, black seed might interfere with immunosuppressive therapy.  Details Animal and in vitro studies suggest that black seed might stimulate immune function (36086,36137,36161). However, other animal studies suggest that black seed may suppress immune function (36085,36142).

PHENYTOIN (Dilantin) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, black seed might increase or decrease levels and effects of phenytoin.  Details In vitro research suggests that thymoquinone, a constituent of black seed, can decrease the metabolism of phenytoin (110281). This effect may be due to inhibition of cytochrome P450 2C9 (CYP2C9). However, animal research shows that black seed decreases the maximum concentration of and total systemic exposure to phenytoin by 57% and 87%, respectively. This seems to be related to increased clearance and steady state volume of distribution (110905). This interaction has not been shown in humans.

PREDNISOLONE Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically black seed might reduce plasma levels and therapeutic effects of prednisolone.  Details In animal research, oral administration of a single dose of black seed oil 15 minutes prior to oral prednisolone decreases the prednisolone maximum plasma concentration by 65% and area under the curve by 25%(114811). This has not been shown in humans.

SEROTONERGIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, combining serotonergic drugs with black seed might increase the risk of serotonergic side effects, including serotonin syndrome and cerebral vasoconstrictive disorders.  Details Animal research suggests that black seed can increase brain serotonin levels (36180,94488). In one case report, a 35-year-old man undergoing endoscopic surgery experienced immediate postoperative serotonin syndrome that was likely associated with the use of black seed oil 600 mg daily starting 4 days before surgery, and precipitated by the use of serotonergic pain medications, including fentanyl and oxycodone (101558). Monitor patients for signs of serotonin syndrome and other serotonergic side effects if using black seed with serotonergic drugs.

SILDENAFIL (Viagra) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, black seed might reduce plasma levels and the therapeutic effects of sildenafil.  Details Animal research shows that black seed reduces the total systemic exposure to sildenafil by 43% (110898). So far, this interaction has not been reported in humans.

WARFARIN (Coumadin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, black seed might increase levels of warfarin and increase the risk of bleeding.  Details In vitro research suggests that thymoquinone, a constituent of black seed, can decrease the metabolism of warfarin (110280). This effect may be due to inhibition of cytochrome P450 2C9 (CYP2C9). The effect of black seed on warfarin metabolism is unclear. This has not been shown in humans.

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General ...Orally and topically, black seed seems to be well tolerated.
Most Common Adverse Effects:
Orally: Constipation, gastric burning or discomfort, nausea, and vomiting.

Dermatologic ...Orally, black seed can cause itching, but this adverse effect is rare (94481). It has also been reported to cause bullous drug eruption and maculopapular eruption (94480,100324). Topically, black seed and its oil have been reported to cause allergic contact dermatitis (36053,36296,36297,100324). Rarely, topical use of the oil has been reported to cause a rash related to drug reaction with eosinophilia and systemic symptoms (DRESS) (110277).

Gastrointestinal ...In a clinical trial, unspecified gastrointestinal complaints occurred in 20% of patients taking black seed oil orally (36071). Gastrointestinal complaints occurred rarely in another clinical trial; however, one patient in this study was hospitalized for nausea and vomiting thought to be associated with black seed oil (110267). Gastrointestinal adverse effects to black seed have included constipation (36180), burning sensation (94487), epigastric discomfort (94479), vomiting (94491), or mild nausea (94481,94489,94491,96927,96929). Gastrointestinal adverse effects to a specific black seed oil formulation containing 5% thymoquinone (BlaQmax) have included mild cases of bloating, burping and mild diarrhea (110264).

Genitourinary ...Orally, relatively severe menstrual bleeding has occurred in one clinical trial (104661).

Hepatic ...While intake of black seed has been associated with hepatotoxicity in some animal research, other animal research has not confirmed this finding (245,95982). One case report describes hepatotoxicity, kidney injury, and rhabdomyolysis occurring in an otherwise healthy 26-year-old male after taking black seed oil 1000 mg twice daily for 1 month. The patient was hospitalized for critical care management, including hemodialysis. After 52 days in the hospital, the patient had recovered and was discharged (114812).

Immunologic ...Orally, black seed has been reported to cause bullous drug eruption and maculopapular eruption (94480,100324). Topically, black seed and its oil can cause allergic contact dermatitis (6,36053,36296,36297,100324,110266). One case of bullous drug eruption with skin detachment has been reported for a 54-year-old woman who used black seed oil orally. The eruptions resolved following treatment with clobetasol propionate 0.05%. Although this patient showed a positive skin prick test for undiluted black seed oil, the tests were negative when the oil was diluted to 10% and 1% (94480). A 28-year-old woman developed a rash following topical use of black seed oil. She was diagnosed with drug reaction with eosinophilia and systemic symptoms (DRESS), including enlarged lymph nodes, and required systemic corticosteroid treatment. This diagnosis was confirmed six months later following confirmation with a patch test (110277). In another case report, a 58-year-old woman developed eczematous lesions on the lower and upper eyelids after topical application of an oil containing black seed. This reaction was followed by the development of a diffuse maculopapular eruption after taking two oral capsules containing black seed oil. It is theorized that the topical application of black seed oil led to systemic sensitization prior to the use of oral black seed in this patient (100324).

Renal ...Orally, black seed might cause renal dysfunction. A case of acute renal failure thought to be related to use of black seed tablets 2-2.5 grams daily has been reported for a 62 year-old patient with diabetes (94477). Additionally, a case of acute kidney injury, rhabdomyolysis, and hepatotoxicity has been reported in an otherwise healthy 26-year-old male after taking black seed oil 1000 mg twice daily for 1 month. The patient was hospitalized for critical care management, including hemodialysis. . After 52 days in the hospital, the patient had recovered and was discharged (114812).

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General ...Orally, olive fruit is well tolerated when used in typical food amounts. Olive leaf extract seems to be well tolerated.
Most Common Adverse Effects:
Orally: Headache and stomach discomfort.

Dermatologic ...Orally, one patient in one clinical trial reported bad skin and acne after using olive leaf extract (101860).

Gastrointestinal ...Orally, three patients in one clinical trial reported stomach ache after using olive leaf extract (101860).

Neurologic/CNS ...Orally, three patients in one clinical trial reported headache after using olive leaf extract (101860).

Psychiatric ...In one case report, a 67-year-old female experienced irritability, anger, a lack of control, and feelings of sadness and negativity after consuming a multi-ingredient product containing olive leaf extract 5 grams, horseradish root, and eyebright daily for 38 days. All psychiatric symptoms disappeared within days of stopping the combined product. It is hypothesized that the hydroxytyrosol component of olive leaf extract contributed to these symptoms due to its chemical similarity to dopamine; however, it is not clear if these symptoms were due to the olive leaf extract or to the other ingredients (96245).

Pulmonary/Respiratory ...Olive tree pollen can cause seasonal respiratory allergy (1543).

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General ...Orally, consuming omega-6 fatty acids in amounts found in foods is well tolerated.

Cardiovascular ...Dietary intake of the omega-6 fatty acid linoleic acid in amounts of 5% to 10% of daily calories is appropriate according to the Dietary Reference Intake (DRI) Acceptable Macronutrient Distribution Range (AMDR) (23723). However, higher intake levels, especially when compared with omega-3 fatty acid intake, might be detrimental. For example, a higher ratio of dietary omega-6 to omega-3 fatty acids is thought to increase the risk of cardiovascular disease compared to a lower ratio (66678). However, the American Heart Association Nutrition Subcommittee of the Council on Nutrition, Physical Activity, and Metabolism, the Council on Cardiovascular Nursing, and the Council on Epidemiology and Prevention, suggest that reduction of omega-6 fatty acids in the diet is unlikely to be beneficial for the cardiovascular system if replaced with saturated or trans-fatty acids (66692). Population research has found that higher intake of omega-6 fatty acids might be associated with hypertension and increased levels of plasma homocysteine, a risk factor for cardiovascular disease and atherosclerosis (65498,66640,66642).

Musculoskeletal ...In epidemiological research, increased intake of omega-6 fatty acids was associated with elevated risk of fracture in the elderly (66662).

Neurologic/CNS ...In epidemiological research, an increased dietary ratio of omega-6 fatty acids to omega-3 fatty acids has been associated with an elevated risk of having a sleep disorder (107001).

Oncologic ...Some population research has found that high omega-6 fatty acid intake or blood levels are associated with an increased risk for cancer, including breast cancer and prostate cancer (3508,7824,66660,66664,66729).

Psychiatric ...In epidemiological research, adolescents with attention-deficit hyperactivity disorder (ADHD) had higher levels of omega-6 and lower levels of omega-3 fatty acids in red blood cells (48200). The role of omega-6 fatty acids in ADHD is unclear; it is possible that the low levels of omega-3 fatty acids and essential fatty acids in general may be playing a role. Also, higher levels of some omega-6 fatty acids in the body are associated with greater depressive symptomology and neuroticism (65815,66659). Higher concentrations of some omega-6 fatty acids in red blood cells of patients with schizophrenia are correlated with positive schizotypal trait measures in healthy adults (66635). This may be related to increased intake of omega-6 fatty acids in the diet of patients with schizophrenia (96916).

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