|Nigella sativa is available in form of seeds, oils and all sorts of ointments and for many of them there are studies suggesting that they work.|
In the following I am going to present an allegedly cursory overview of the existing evidence with a focus on those health benefits that could be relevant for the average and extra-ordinary SuppVersity reader.
- General anti-oxidant effects - The complete oil of N. sativa,
as well as thymoquinone (the main compound of the
essential oil) have been shown to significantly reduce non-enzymatic lipid peroxidation
in liposomes (Houghton. 1995). Significant anti-oxidant effects have also been observed for other compounds isolated from N. sativa, uncluding thymoquinone, carvacol, t-anethole and 4-terpineol.
Figure 1: The tymoquinone rich fraction of blackseed (TQRF-X) has dose dependent (L,M,H) effects on antioxidant enzyems in hypercholesterolemic (Ismail. 2010).
Most importantly, though, the different compounds in the oil were found to act in a synergistic manner (i.e. more than the mere summation of the actions of the individual compounds). This stresses the importance of using the whole oil (or the crude extract) of the seeds in pharmacological studies.
As Ali and Blunden point out in their review of the literature, "the antioxidant property of N. sativa is multifactorial, [but] it does not seem to involve iron-complexing activity (Ali. 2003). It rather appears as if its general ability to scavenge free radicals, which may be, at least partially, the basis of many human diseases and conditions, could be at the heart of its ability to protect, for example, against CCl4 hepatotoxicity (Nagi. 1999), liver fibrosis and cirrhosis (Türkdogan. 2000), and hepatic damage induced by Schistosoma mansoni infection (Mahmoud. 2002).
- Antiinflammatory and analgesic actions -It's one thing to scavenge free radicals. It's yet a completely different thing to effectively reduce the inflammation that's often, but not always triggered by the presence of free radicals. Against that background it's important to note that an aqueous extract from nigella sativa exhibits strong anti-inflammatory effects, as well (Al-Ghamdi, 2001). Using carrageenan-induced
paw oedema as a model of inflammation, and the hot
plate reaction time as a model of nociception, the
extract was found to possess significant antiinflammatory
and analgesic (=pain reducing) action.
As Ali & Blunden (2003) point out, this finding lends some credence to the folk medicinal use of the plant as an antiinflammatory and analgesic substance, and also confirms previous reports on the antinociceptive (Abdel-Fattah. 2000) and antiinflammatory (Mutabagani. 1997) effects of N. sativa oil and its major component, thymoquinone, in mice.
The possible mechanism by which N. sativa exerts its antiinflammatory action has been studied. Thymoquinone has been shown to be a potent inhibitor of eicosanoid generation, namely thromboxane B2 and leucotrienes B4, by inhibiting both cyclooxygenase and lipooxygenase, respectively (Houghton. 1995). Interestingly, it was found that the fixed oil of N. sativa had both antioxidant and anti-eicosanoid effects greater than thymoquinone, which is its active constituent (Houghton. 1995)
|Chemical structure of some of the main potentially bioactive compounds in Nigella sativa (Paarakh. 2010).|
In addition, it contains four alkaloids and several monodesmosidic triterpene saponins. What? Yeah... unfortunately, we know only of few of the (potentially) active ingredients and even less about what exactly they do.
- Anti-Cancer Effect - In an in-vitro study from the late 1990s researchers from the Tobacco and Health Research Institute in Lexington were able to show that the thymoquinone (TQ) and dithymoquinone (DIM) content of nigella sativa have the astonishing ability to kill several parental and multi-drug resistant (MDR) human tumor cell lines (Worthen. 1997).
- Anti-allergic effects - In a study from 2003 Kalus et al. observed significant reductions in subjective feeling of allergic symptoms in 152 patients with allergic diseases (allergic rhinitis, bronchial asthma, atopic eczema) who were treated with Nigella sativa oil, given in capsules at a dose of 40 to 80 mg/kg/day.
- Anti-diabetes effects: The volatile compounds in nigella sativa oil have been shown to exert potent glucose lowering effects in healthy and diabetic animals (Al-Hader. 1993). Effects that occured in the absence of changes in insulin levels and are almost unsettlingly pronounced.
Figure 4: Reduction in fasting blood glucose in the hours after the administration of 50mg/kg volatile oil extract to normal and diabetic rodents (Al-Hader. 1993).
With comparatively lower doses of only 5ml of nigella sativa oil, Mohtashami et al. have recently demonstrated that the beneficial effects on blood glucose are not rodent specific.
Figure 5: Blackseed consumed in 2x2.5ml servings everydy improves blood glucose management in healthy humans, too (Mohtashami. 2011)
In view of the comparatively small reductions in blood sugar (see Figure 5), it's also not surprisng that the only side effect was an occasional case of transient nausea. Notable changes in liver enzyme and kidney functional adverse effects, on the other hand, were not observed..
Similar results have been reported for subjects with diabetes (Najmi. 2008), intact and diabetic rats (Hawsawi. 2001; Houcher. 2007) and in several cell models, like muscle cells, where it increases AMPK and GLUT4 expression (Benhaddou-Andaloussi. 2011) or the Langerhans cells (Rchid. 2004) of the pancreas of which Fararh et al. (2002) were able to show that they can partly recover their ability to release insulin in a rodent model of diabetes, when nigella sativa is administered in conjunction with nicotinic acid.
- Cardiovascular effects - The results of a 2014 study by Mohammad et al. indicate that "[t]he use of N. sativa as an alternative therapy for
hypercholesterolemia could have profound impact on the management of CVD among menopausal women
especially in countries where it is readily available." In the corresponding study 1g of nigella sativa powder consumed after breakfast lead to significant improvements in lipid profiles of menopausal women (decreased
total cholesterol, low density lipoprotein cholesterol and triglyceride, and increased high density lipoprotein
cholesterol)within 2 months. Improvements that were lost almost completely after one month without the capped Nigella sativa supplement.
Rather ambigous - at least at first sight - are the effects of nigella sativa on the physiology of the heart, while Al-Asoom et al. (2014a) were able to show that the IFG-1 boosting effects Nigella sativa exerts on exercising rats could make it a valuable tool for the treatment of heart failure with superior advantages to exercise training alone, the same effects are often mentioned as potential unwanted side effects of Nigella sativa.
Figure 6: In trained rats, the Nigella sativa induced boost in IGF-1 (left) promotes the exercise induced increase in heart weight (right | Al-Asoom. 2014a)
- Abbas, Ayman Talatt, et al. "Effect of dexamethasone and Nigella sativa on peripheral blood eosinophil count, IgG1 and IgG2a, cytokine profiles and lung inflammation in murine model of allergic asthma." The Egyptian journal of immunology/Egyptian Association of Immunologists 12.1 (2004): 95-102.
- Abdel-Fattah, Abdel-Fattah Mohamed, Kinzo Matsumoto, and Hiroshi Watanabe. "Antinociceptive effects of< i> Nigella sativa</i> oil and its major component, thymoquinone, in mice." European journal of pharmacology 400.1 (2000): 89-97.
- Al-Sa'aidi, J. A. A., A. L. D. Al-Khuzai, and N. F. H. Al-Zobaydi. "Effect of alcoholic extract of Nigella sativa on fertility in male rats." Iraq J Verterin Sci 23 (2009): 123-8.
- Al-Asoom, L. I., et al. "Effect of Nigella sativa Supplementation to Exercise Training in a Novel Model of Physiological Cardiac Hypertrophy." Cardiovascular toxicology (2014a): 1-8.
- Al-Asoom, Lubna Ibrahim, et al. "Comparison of Nigella sativa-and Exercise-Induced Models of Cardiac Hypertrophy: Structural and Electrophysiological Features." Cardiovascular toxicology (2014b): 1-6.
- Al-Awadi, Fatania, and U. Shamte. "The effect of a plants mixture extract on liver gluconeogenesis in streptozotocin induced diabetic rats." Diabetes research (Edinburgh, Scotland) 18.4 (1991): 163-168.
- Al-Hader, Aqel, M. Aqel, and Z. Hasan. "Hypoglycemic effects of the volatile oil of Nigella sativa seeds." Pharmaceutical Biology 31.2 (1993): 96-100.
- Ali, B. H., and Gerald Blunden. "Pharmacological and toxicological properties of Nigella sativa." Phytotherapy Research 17.4 (2003): 299-305.
- Ahlatci, Adem, et al. "Radiation-modifying abilities of< i> Nigella sativa</i> and Thymoquinone on radiation-induced nitrosative stress in the brain tissue." Phytomedicine 21.5 (2014): 740-744.
- Benhaddou-Andaloussi, Ali, et al. "The in vivo antidiabetic activity of Nigella sativa is mediated through activation of the AMPK pathway and increased muscle Glut4 content." Evidence-Based Complementary and Alternative Medicine 2011 (2011).
- Cikman, Oztekin, et al. "Radioprotective Effects of Nigella Sativa Oil Against Oxidative Stress in Liver Tissue of Rats Exposed to Total Head Irradiation." Journal of Investigative Surgery (2014).
- Fararh, K. M., et al. "Isulinotropic properties of< i> Nigella sativa</i> oil in Streptozotocin plus Nicotinamide diabetic hamster." Research in veterinary science 73.3 (2002): 279-282.
- Hawsawi, Zubaida A., Basil A. Ali, and Abdullah O. Bamosa. "Effect of Nigella sativa (black seed) and thymoquinone on blood glucose in albino rats." Annals of Saudi medicine 21.3-4 (2001): 242-244.
- Houcher, Zahira, et al. "Effects of methanolic extract and commercial oil of Nigella sativa L. on blood glucose and antioxidant capacity in alloxan-induced diabetic rats." Pteridines 18.1 (2007): 8-18.
- Houghton PJ, Zarka R, de las Heras B, Hoult JRS."Fixed oil of Nigella sativa and derived thymoquinone inhibit eicosanoid generation in leukocytes and membrane lipid peroxidation". Planta Med 61 (1995): 33–36.
- Ichwan, S. J., et al. "Apoptotic Activities of Thymoquinone, an Active Ingredient of Black Seed (Nigella sativa), in Cervical Cancer Cell Lines." The Chinese journal of physiology 57.5 (2014).
- Lautenbacher LM. "Schwarzkümmelöl." Dtsch Apoth Ztg 137 (1997): 68–69.
- Khan, Fazal, et al. "Evaluation of the effect of Nigella sativa extract on human hepatocellular adenocarcinoma cell line (HepG2) in vitro." BMC Genomics 15.Suppl 2 (2014): P63.
- Kundu, Juthika, et al. "Mechanistic Perspectives on Cancer Chemoprevention/Chemotherapeutic Effects of Thymoquinone." Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis (2014).
- Mahmoud, M. R., H. S. El-Abhar, and S. Saleh. "The effect of< i> Nigella sativa</i> oil against the liver damage induced by< i> Schistosoma mansoni</i> infection in mice." Journal of ethnopharmacology 79.1 (2002): 1-11.
- Mohtashami, R., et al. "Blood Glucose Lowering Effects of Nigella Sativa L. Seeds Oil in Healthy Volunteers: a Randomized, Double-Blind, Placebo-Controlled Clinical Trial." Journal of Medicinal Plant 10.36 (2011): 90-94.
- Mutabagani, A., and S. A. M. El-Mahdy. "A study of the anti-inflammatory activity of Nigella sativa L. and thymoquinone in rats." Saudi Pharmaceutical Journal 5 (1997): 110-113.
- Nagi, Mahmoud N., et al. "Thymoquinone protects against carbon tetrachloride hetatotoxicity in mice via an antioxidant mechanism." IUBMB Life 47.1 (1999): 153-159.
- Najmi, Ahmad, et al. "Effect of Nigella sativa oil on various clinical and biochemical parameters of insulin resistance syndrome." International journal of diabetes in developing countries 28.1 (2008): 11.
- Ozugurlu, F., et al. "The effect of Nigella sativa oil against experimental allergic encephalomyelitis via nitric oxide and other oxidative stress parameters." Cellular and molecular biology (Noisy-le-Grand, France) 51.3 (2005): 337-342.
- Pace, Andrea, et al. "Neuroprotective effect of vitamin E supplementation in patients treated with cisplatin chemotherapy." Journal of Clinical Oncology 21.5 (2003): 927-931.
- Paarakh, Padmaa M. "Nigella sativa Linn.–A comprehensive review." Indian J Nat Prod Resour 1 (2010): 409-29.
- Rchid, Halima, et al. "Nigella sativa seed extracts enhance glucose‐induced insulin release from rat‐isolated Langerhans islets." Fundamental & clinical pharmacology 18.5 (2004): 525-529.
- Sindi, Abrar, and Karen Carlberg. "Thymoquinone, a component of the Middle East spicy seed Nigella sativa, decreases oxidative DNA damage in a rat model of mammary cancer (693.21)." The FASEB Journal 28.1 Supplement (2014): 693-21.
- Tabasi, Nafise, et al. "Cytotoxic and apoptogenic properties of Nigella sativa and thymoquinone, its constituent, in human renal cell carcinoma are comparable with cisplatin." Food and Agricultural Immunology ahead-of-print (2014): 1-19.
- Türkdoğan, M. K., et al. "The role of antioxidant vitamins (C and E), selenium and Nigella sativa in the prevention of liver fibrosis and cirrhosis in rabbits: new hopes." DTW. Deutsche tierarztliche Wochenschrift 108.2 (2001): 71-73.
- Worthen, David R., Omar A. Ghosheh, and P. A. Crooks. "The in vitro anti-tumor activity of some crude and purified components of blackseed, Nigella sativa L." Anticancer research 18.3A (1997): 1527-1532.