Nigella sativa improves anemia, enhances immunity and relieves iron overload-induced oxidative stress as a novel promising treatment in children having beta-thalassemia major

Manuka combinations with nigella sativa and hydroxyurea in treating iron overload of pediatric β-thalassemia major, randomized clinical trial

Background

β-thalassemia major is microcytic hypochromic anemia disorder inherited from parents, resulting from a mutation in the β-globin locus. As a result, a quantitative defective hemoglobin synthesis and relative excess in α-globin is occurred. As such, frequent blood transfusion is required, that leads to iron overload. Iron overload results in several pathological complications, including cell death, tissue injury, organ dysfunction, and liver fibrosis. The present study examined the effectiveness of nigella Sativa and manuka honey combination or manuka honey alone to the conventional therapy (Deferasirox + blood transfusion) used for preventing and managing iron overload in pediatric β-thalassemia major patients.

Methods

One hundred sixty-five patients participated in this randomized, double-blind, standard therapy-controlled, parallel-design multisite trial. The patients were randomly allocated into three groups, receiving either 500 mg nigella sativa oil combined with manuka honey lozenge (344 mg) daily or manuka honey alone plus the conventional therapy for ten treatment months. Ferritin level, serum iron, transferrin saturation, total iron binding capacity, alanine transaminase, and aspartate transaminase were determined at baseline and month 10.

Results

Eventually, serum ferritin and iron were decreased significantly in the nigella sativa + manuka honey group as compared with the control group. Other clinical parameters were significantly impacted. The level of alanine transaminase and aspartate transaminase were significantly decreased in the nigella sativa plus manuka honey group compared with the control group.

Conclusion

Results showed that nigella sativa plus manuka honey was more effective than manuka alone or the conventional treatment alone in managing iron overload of β-thalassemia major patients.

Nigella sativa oil restores hormonal levels, and endocrine signals among thyroid, ovarian, and uterine tissues of female Wistar rats following sodium fluoride toxicity

The current study aimed to explore the possible prophylactic and therapeutic effect of Nigella sativa L. oil (NSO) against disruption of endocrine signals and injuries in the thyroid gland, ovary, and uterine tissues induced by sodium fluoride (NaF). Twenty-eight mature female Wistar rats were randomly allocated into four experimental groups (n = 7/group) as follows: control group; NaF group, orally received NaF (20 mg/kg b.wt.) daily; NSO/NaF, orally received NSO (300 mg/kg b.wt.) two weeks before being given NaF and continued throughout the experiment; and NSO+NaF group orally received NSO concurrently with NaF. Our results indicated that NSO restored hormonal balance and suppressed oxidative damage and inflammation. Moreover, the levels of triiodothyronine, thyroxine, thyroid peroxidase, estrogen (E2), progesterone, follicle-stimulating hormone, and luteinizing hormone were elevated, while prostaglandins F2-α and cortisol levels were decreased in NSO treated groups compared to NaF-intoxicated rats. As well, NSO significantly boosted levels of antioxidant molecules, and lowered lipid peroxidation of examined tissues, unlike NaF-treated group. NSO also up-regulated antioxidant enzymes, anti-apoptotic protein, zona pellucida sperm-binding protein, bone morphogenetic protein, and thyroid stimulating hormone, conversely down-regulated inflammatory cytokines, apoptotic proteins, estrogen receptor-α, estrogen receptor-β, and thyroid stimulating hormone receptors compared to NaF-intoxicated group. Additionally, NSO ameliorated tissue damage of the thyroid gland, ovary, and uterus induced by NaF. -Overall, the prophylactic group (NSO/NaF) performed better antioxidant and anti-inflammatory activities than the treated group almost in all examined tissues, which is reflected by the improvement in the structure of the thyroid, ovarian, and uterine tissues.

Effect of Nigella sativa on general health and immune system in young healthy volunteers; a randomized, placebo-controlled, double-blinded clinical trial

Nigella sativa ( N. sativa) is traditionally used as an immune enhancer in different communities. The aim of this study was to evaluate the effect of N. sativa on immunity related parameters in young healthy subjects. This study was a double blind, randomized, placebo controlled clinical trial. Fifty-two healthy subjects (48 male and 4 female) 18-25 years old were enrolled in the study. They were randomly divided into four groups; the first received charcoal capsules and served as controls and the other three received 0.5, 1 g, and 2 g of powdered N. sativa capsules, respectively. Two blood samples were obtained from all participant, before initiation of the trial and at the end of the four weeks intervention. One sample was used for routine health screening by evaluating liver and renal functions as well as complete blood count and differential. The second sample was used to measure certain cytokines including; IL-1, IL-4, IL-6, IL-10, and TNF. A third and fourth samples were obtained from the last cohort of subjects before and after treatment; the third was used for measuring immunoglobulins and CD profile and the fourth for evaluating certain gene expressions (INF-γ, NF-κ-B, TNF-α, IL-1β, IL-13, IL-8, and IL-6). Only 1 g dose of N. sativa produced a significant elevation in total lymphocyte count, CD3+ and CD4+ counts. One gram N. sativa increased the absolute lymphocyte count from 1850±0.24 to 2170±0.26 (p=0.008), CD3+ from 1184.4±75.60 to 1424±114.51 (p=0.009), and CD4+ from 665.6±141.66 to 841±143.36 (p=0.002).  This elevation in T cells was lost by increasing the dose of N. sativa to 2g. The rest of the parameters were not changed significantly in all doses. The results show a promising immunopotentiation effect of N. sativa by elevating helper T cells and the optimum dose for young age group seems to be 1 g.

Al-Hijamah (Prophetic Wet Cupping Therapy) is a Novel Adjuvant Treatment for Viral Hepatitis That Excretes Viral Particles and Excess Ferritin Percutaneously, Synergizes Pharmacotherapy, Enhances Antiviral Immunity and Helps Better HCC Prevention and Treatment: A Novel Evidence-Based Combination with Prophetic Medicine Remedies

Viral hepatitis progresses to liver cirrhosis and HCC. Several challenges are facing Sovaldi treatment to viral C hepatitis, eg, viral resistance, difficulty to treat all genotypes, and inability to access treatments in low-income countries. Also, current treatments to Hepatitis B are still challenging. Ideal treatments to viral hepatitis should decrease the viral load, enhance antiviral immunity and repair the viruses-induced tissue damage. That is still beyond reach. High serum ferritin in viral hepatitis correlates with chronicity, increased necro-inflammation, hepatotoxicity, progression to cirrhosis, progression to HCC, unresponsiveness to treatments and viremia. Previously, Al-hijamah (wet cupping therapy of prophetic medicine) significantly cleared thalassemic children of causative pathological substances (CPS), eg, excess ferritin, free radicals and serum lipids. Moreover, Al-hijamah significantly increased the antioxidant power and potentiated the natural antiviral immunity, eg, increasing CD4 count, CD8 count and CD4/CD8 ratio. Prophet Muhammad peace be upon him said: "If there is a benenvolence (benefit) in any of your medicines, benefit will be in shrtat mihjam (Al-hijamah), honey drink, and a stinge of fire compatible with disease and I do not like to cauterize". Likewise, the author suggests Al-hijamah as a novel promising adjuvant treatment for viral hepatitis (B and C) for percutaneous excretion of CPS as hepatitis viral particles, excess ferritin, inflammatory mediators, free radicals, and antigen-antibody complexes. Published reports proved that Al-hijamah exerted tissue-protective effects, and cleared blood through the fenestrated skin capillaries in a pressure-dependent and size-dependent manner (a kidney-like manner). That collectively may decrease the viral load for better HCC prevention and supports the evidence-based Taibah theory (Taibah mechanism). Same therapeutic benefits apply to other viral illnesses as AIDS. Even after HCC development, Al-hijamah is quite mandatory for excretion and clearance of CPS that favor malignancy, eg, lactate (Warburg effect), growth factors, metalloproteinases, and others. Al-hijamah-induced immune potentiation benefits HCC patients. Combining Al-hijamah with other natural antioxidant remedies of prophetic medicine, eg, nigella sativa, costus, natural honey, Zamzam water and others will maximize the therapeutic benefits. In conclusion, Al-hijamah and other prophetic medicine remedies are recommended adjuvants to current pharmacological treatments to viral hepatitis and HCC.

Antioxidant and Lipid-Lowering Effects of Buriti Oil (Mauritia flexuosa L.) Administered to Iron-Overloaded Rats

The indiscriminate use of oral ferrous sulfate (FeSO4) doses induces significant oxidative damage to health. However, carotene-rich foods such as buriti oil can help the endogenous antioxidant defense and still maintain other body functions. This study aimed to assess the effects of buriti oil intake in iron-overloaded rats by FeSO4 administration. Buriti oil has β-carotene (787.05 mg/kg), α-tocopherol (689.02 mg/kg), and a predominance of monounsaturated fatty acids (91.30 g/100 g). Wistar rats (n = 32) were subdivided into two control groups that were fed a diet containing either soybean or buriti oil; and two groups which received a high daily oral dose of FeSO4 (60 mg/kg body weight) and fed a diet containing either soybean (SFe) or buriti oil (Bfe). The somatic and hematological parameters, serum lipids, superoxide dismutase (SOD), and glutathione peroxidase (GPx) were determined after 17 days of iron overload. Somatic parameters were similar among groups. BFe showed a decrease in low-density lipoprotein (38.43%) and hemoglobin (7.51%); an increase in monocytes (50.98%), SOD activity in serum (87.16%), and liver (645.50%) hepatic GPx (1017.82%); and maintained serum GPx compared to SFe. Buriti oil showed systemic and hepatic antioxidant protection in iron-overloaded rats, which may be related to its high carotenoid, tocopherol, and fatty acid profile.

Hepatic Response to the Interaction Between Thymoquinone and Iron-Dextran: an In Vitro and In Vivo Study

Iron is one of the most important essential elements for cell function. However, iron overload can exert destructive effects on various tissues, especially the liver. The present study was designed to evaluate the effect of thymoquinone (TQ) on hepatotoxicity induced by iron-overload in in vitro and mouse model. After in vitro studies, thirty mice were divided into five groups, six each. Group 1 received normal saline. Group 2 received five doses of iron dextran (i.p; 100 mg/kg, one dose every 2 days). Group 3 received TQ (orally, 2 mg/kg/day). Groups 4 and 5 were administrated iron dextran saline (i.p; 100 mg/kg, one dose every 2 days) following treatment with 0.5 and 2 mg/kg/day of TQ, respectively. Based on the findings of the DPPH experiment, although TQ has significant anti-radical potential, at a safe dose of 15 × 10⁺³ nM, it reduced the IC₅₀ of iron dextran on HepG2 cells by about 25%, in in vitro. Following administration of low-dose TQ (0.5 mg/kg), a significant improvement was observed in serum hepatic enzymes activity and hepatic lipid peroxidation compared to iron dextran. However, administration of TQ-high dose (2 mg/kg) led to decrease antioxidant defense alongside increased serum hepatic enzymes and pathological damages in iron dextran-treated animals. Due to the different efficacy of TQ in treatment groups, it seems that the TQ therapeutic index is low and does not have significant safety in the iron overload status.

Biochemical Origin of the Warburg Effect in Light of 15 Years of Research Experience: A Novel Evidence-Based View (An Expert Opinion Article)

Cancer cells strongly upregulate glucose uptake and glycolysis to produce vital biomolecules for cancer cell survival, proliferation, and metastasis as ATP, lipids, proteins, nucleotides, and lactate. The Warburg effect is tumours' unique glucose oxidation to give lactate (not pyruvate) even in the presence of oxygen. Nicotinamide adenine dinucleotide (NAD/NADH.H) is used in glycolysis via glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and lactate dehydrogenase (LDH). Both catalyse reversible biochemical reactions to produce 1,3-diphosphoglycerate and lactate, respectively. In this expert opinion and based on published evidence, the author suggests that: "In transformed cells and hyperglycolytic cancer cells, the Warburg effect (permanent conversion of pyruvate to lactate) occurs secondary to a vicious cycle and a closed circuit between GAPDH and LDH (reaction of carcinogenesis) causing increased endogenous oxidative stress and subsequent carcinogenesis. Mitochondrial defects in cancer cells cause hyperglycolysis resulting in NADH.H accumulation (produced during GAPDH step) that obligatorily drives LDH to become an irreversible reaction in the direction of lactate formation (Warburg effect) but not pyruvate formation. Likewise, LDH oxidizes NADH.H producing excessive NAD⁺ that secondarily drives GAPDH reaction to be irreversible to produce NADH.H and so on. Pyruvate is an antioxidant while lactate is pro-oxidant, causing increased endogenous oxidative stress in cancer cells, tumour's hypoxia and obligatory hyperglycolysis with NADH.H overproduction (GAPDH step) to be consumed in the LDH step for lactate production and NAD⁺ generation (utilized by GAPDH) and so on". This confirms Warburg's origin of cancer cells. Best anticancer applications based on this hypothesis are: breaking this closed vicious circle using siRNA to target GAPDH and LDH, avoiding strong oxidants (as many cancer chemotherapeutics), and using strong antioxidants for causing antioxidant-oxidant antagonism or antioxidant-lactate antagonism to inhibit the Warburg effect. Strong natural antioxidants of prophetic medicine (related to Prophet Muhammad peace be upon him) such as Zamzam water, Nigella sativa, costus, Ajwa date fruit, olive oil, Al-hijamah and natural honey are strongly recommended to prevent and antagonize the Warburg effect.

Therapeutic roles of plants for 15 hypothesised causal bases of Alzheimer's disease

Alzheimer's disease (AD) is progressive and ultimately fatal, with current drugs failing to reverse and cure it. This study aimed to find plant species which may provide therapeutic bioactivities targeted to causal agents proposed to be driving AD. A novel toolkit methodology was employed, whereby clinical symptoms were translated into categories recognized in ethnomedicine. These categories were applied to find plant species with therapeutic effects, mined from ethnomedical surveys. Survey locations were mapped to assess how this data is at risk. Bioactivities were found of therapeutic relevance to 15 hypothesised causal bases for AD. 107 species with an ethnological report of memory improvement demonstrated therapeutic activity for all these 15 causal bases. The majority of the surveys were found to reside within biodiversity hotspots (centres of high biodiversity under threat), with loss of traditional knowledge the most common threat. Our findings suggest that the documented plants provide a large resource of AD therapeutic potential. In demonstrating bioactivities targeted to these causal bases, such plants may have the capacity to reduce or reverse AD, with promise as drug leads to target multiple AD hallmarks. However, there is a need to preserve ethnomedical knowledge, and the habitats on which this knowledge depends.

Nigella sativa L. Phytochemistry and Pharmacological Activities: A Review (2019-2021)

Medicinal and aromatic plants are mainly characterized by the presence of different bioactive compounds which exhibit various therapeutic activities. In order to investigate the different pharmacological properties of different Nigella sativa extracts, a multitude of research articles published in the period between 2019 and 2021 were obtained from different databases (Scopus, Science Direct, PubMed, and Web of Science), and then explored and analyzed. The analysis of the collected articles allows us to classify the phytochemicals and the pharmacological activities through their underlying molecular mechanisms, as well as to explore the pharmacological activities exhibited by several identified compounds in Nigella sativa which allow a better understanding, and better elucidation, of the bioactive compounds responsible for the pharmacological effects. Also shown are the existence of other bioactive compounds that are still unexplored and could be of great interest. This review could be taken as a guide for future studies in the field.

Effect of Nigella sativa on general health and immune system in young healthy volunteers; a randomized, placebo-controlled, double-blinded clinical trial

Nigella sativa (N. sativa) is traditionally used as an immune enhancer in different communities. The aim of this study was to evaluate the effect of N. sativa on immunity related parameters in young healthy subjects. This study was a double blind, randomized, placebo controlled clinical trial. Fifty-two healthy subjects (48 male and 4 female) 18-25 years old were enrolled in the study. They were randomly divided into four groups; the first received charcoal capsules and served as controls and the other three received 0.5, 1 g, and 2 g of powdered N. sativa capsules, respectively. Two blood samples were obtained from all participant, before initiation of the trial and at the end of the four weeks intervention. One sample was used for routine health screening by evaluating liver and renal functions as well as complete blood count and differential. The second sample was used to measure certain cytokines including; IL-1, IL-4, IL-6, IL-10, and TNF. A third and fourth samples were obtained from the last cohort of subjects before and after treatment; the third was used for measuring immunoglobulins and CD profile and the fourth for evaluating certain gene expressions (INF-γ, NF-κ-B, TNF-α, IL-1β, IL-13, IL-8, and IL-6). Only 1 g dose of N. sativa produced a significant elevation in total lymphocyte count, CD3+ and CD4+ counts. One gram N. sativa increased the absolute lymphocyte count from 1850±0.24 to 2170±0.26 (p=0.008), CD3+ from 1184.4±75.60 to 1424±114.51 (p=0.009), and CD4+ from 665.6±141.66 to 841±143.36 (p=0.002).  This elevation in T cells was lost by increasing the dose of N. sativa to 2g. The rest of the parameters were not changed significantly in all doses. The results show a promising immunopotentiation effect of N. sativa by elevating helper T cells and the optimum dose for young age group seems to be 1 g.

Protective effects of curcumin against iron-induced toxicity

Iron is an essential element in cellular metabolism that participates in many biochemical reactions. Nevertheless, iron overload in the body is the cause of damage in some organs including liver, glands, brain, heart, gastrointestinal tract and lung. Iron chelation therapy could be considered as an effective approach for removing excess iron. Deferoxamine, deferiprone and deferasirox are three common iron chelators in clinical practice but cause several side effects. In this context, the use of curcumin, a dietary phytochemical derived from turmeric, as a natural and safe antioxidant with iron-chelating activity may be a useful strategy for the management of iron overload. This review focuses on the deleterious effect of iron accumulation in different organs of the body as well as the therapeutic potential of curcumin against iron-induced toxicity.

Black Cumin (Nigella sativa L.): A Comprehensive Review on Phytochemistry, Health Benefits, Molecular Pharmacology, and Safety

Mounting evidence support the potential benefits of functional foods or nutraceuticals for human health and diseases. Black cumin (Nigella sativa L.), a highly valued nutraceutical herb with a wide array of health benefits, has attracted growing interest from health-conscious individuals, the scientific community, and pharmaceutical industries. The pleiotropic pharmacological effects of black cumin, and its main bioactive component thymoquinone (TQ), have been manifested by their ability to attenuate oxidative stress and inflammation, and to promote immunity, cell survival, and energy metabolism, which underlie diverse health benefits, including protection against metabolic, cardiovascular, digestive, hepatic, renal, respiratory, reproductive, and neurological disorders, cancer, and so on. Furthermore, black cumin acts as an antidote, mitigating various toxicities and drug-induced side effects. Despite significant advances in pharmacological benefits, this miracle herb and its active components are still far from their clinical application. This review begins with highlighting the research trends in black cumin and revisiting phytochemical profiles. Subsequently, pharmacological attributes and health benefits of black cumin and TQ are critically reviewed. We overview molecular pharmacology to gain insight into the underlying mechanism of health benefits. Issues related to pharmacokinetic herb-drug interactions, drug delivery, and safety are also addressed. Identifying knowledge gaps, our current effort will direct future research to advance potential applications of black cumin and TQ in health and diseases.

Alkaloids Used as Medicines: Structural Phytochemistry Meets Biodiversity-An Update and Forward Look

Selecting candidates for drug developments using computational design and empirical rules has resulted in a broad discussion about their success. In a previous study, we had shown that a species' abundance [as expressed by the GBIF (Global Biodiversity Information Facility)] dataset is a core determinant for the development of a natural product into a medicine. Our overarching aim is to understand the unique requirements for natural product-based drug development. Web of Science was queried for research on alkaloids in combination with plant systematics/taxonomy. All alkaloids containing species demonstrated an average increase of 8.66 in GBIF occurrences between 2014 and 2020. Medicinal Species with alkaloids show higher abundance compared to non-medicinal alkaloids, often linked also to cultivation. Alkaloids with high biodiversity are often simple alkaloids found in multiple species with the presence of 'driver species' and are more likely to be included in early-stage drug development compared to 'rare' alkaloids. Similarly, the success of an alkaloid containing species as a food supplement ('botanical') is linked to its abundance. GBIF is a useful tool for assessing the druggability of a compound from a certain source species. The success of any development programme from natural sources must take sustainable sourcing into account right from the start.

Natural Antioxidants in Anemia Treatment

Anemia, characterized by a decrease of the hemoglobin level in the blood and a reduction in carrying capacity of oxygen, is a major public health problem which affects people of all ages. The methods used to treat anemia are blood transfusion and oral administration of iron-based supplements, but these treatments are associated with a number of side effects, such as nausea, vomiting, constipation, and stomach pain, which limit its long-term use. In addition, oral iron supplements are poorly absorbed in the intestinal tract, due to overexpression of hepcidin, a peptide hormone that plays a central role in iron homeostasis. In this review, we conducted an analysis of the literature on biologically active compounds and plant extracts used in the treatment of various types of anemia. The purpose of this review is to provide up-to-date information on the use of these compounds and plant extracts, in order to explore their therapeutic potential. The advantage of using them is that they are available from natural resources and can be used as main, alternative, or adjuvant therapies in many diseases, such as various types of anemia.

Proteomic analysis of oilseed cake: a comparative study of species-specific proteins and peptides extracted from ten seed species

BACKGROUND

In recent years there has been a visible trend among consumers to move away from consuming meat in favor of plant products. Meat producers have therefore been trying to meet the expectations of consumers by introducing new products to the food market with a greater proportion of plant ingredients. Meat products are enriched not only by the addition of vegetable oils but also by ground or whole oilseeds or their preparation. In this study, we present in-solution tryptic digestion and an ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS/MS)-based proteomics approach to investigate specific proteins and peptides of ten oilseed cakes, by-products of cold pressing oil from coconut, evening primrose, hemp, flax, milk thistle, nigella, pumpkin, rapeseed, sesame, and sunflower seeds, for authentication purposes.

RESULTS

We identified a total of 229 unique oilseed proteins. The number of specific proteins varied depending on the sample, from 4 to 48 in evening primrose and sesame. Moreover, we identified approximately 440 oilseed unique peptides in the cakes of all the analyzed oilseeds; the largest amounts were found in sesame (107 peptides), sunflower (100), pumpkin, hemp (42), rapeseed (36), and flax cake (35 peptides).

CONCLUSIONS

We provide novel information on unique / species-specific peptide markers that will extend the scope of testing the authenticity of a wide range of foods. The results of this peptide discovery experiment may further contribute to the development of targeted methods for the detection and quantification of oilseed proteins in processed foods, and thus to the improvement of food quality. © 2020 Society of Chemical Industry.

Effect of Nigella sativa L. supplementation on inflammatory and oxidative stress indicators: A systematic review and meta-analysis of controlled clinical trials

AIMS

The objective of the present study was to perform a systematic review and meta-analysis on randomized controlled trials (RCTs) assessing the effects of Nigella sativa L. supplementation on the circulating inflammatory and oxidative stress markers, including C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), total antioxidant capacity (TAC) and malondialdehyde (MDA).

METHODS

Systematic search was performed up to March 2020 using PubMed, Scopus, and ISI web of science databases. Two reviewers independently assessed study eligibility, extracted data, and evaluated methodological quality of included primary studies. Statistical heterogeneity was assessed using I-square (I²) statistic. Data were pooled by using the random-effect model and standardized mean difference (SMD) was considered as the summary effect size.

RESULTS

Twelve trials were identified to be suitable for our meta-analysis. The pooled results using random effects model indicated that Nigella sativa supplementation significantly reduced CRP (SMD: -0.35; 95% CI: -0.59, -0.12, P < 0.001, I² = 10.5%) and MDA concentrations (SMD: -0.56; 95% CI: -0.98, -0.15, P < 0.001, I² = 64.7%). Moreover, Nigella sativa supplementation increased TAC (SMD: 0.48; 95% CI: 0.09, 0.87, P = 0.01, I² = 65.6%) levels; however, it did not affect TNF-α (SMD: -0.35; 95% CI: -0.70, 0.01, P = 0.05, I² = 58.2%).

CONCLUSION

Nigella sativa supplementation is associated with improved inflammation and oxidative status. Additional prospective studies are recommended using higher supplementation doses and longer intervention period.

Effect of Nigella sativa Supplementation on Oxidative Stress and Antioxidant Parameters: A Meta-Analysis of Randomized Controlled Trials

INTRODUCTION

Nigella sativa is a commonly used traditional medicine which has been shown to have antioxidant properties. However, its supplementation in patients of clinical trials showed conflicting results. Materials and Method. Relevant articles were searched through PubMed/Medline, SCOPUS, and Google Scholar databases using "Nigella sativa" or "black seed" or "black caraway" or "thymoquinone" and "oxidative stress" or "antioxidant" and "clinical trial" keywords. Randomized, placebo-controlled human interventions using Nigella sativa were included in this study. The methodological quality of studies was assessed using Jadad's quality scales.

RESULTS

Five studies using 293 subjects met the inclusion criteria. The overall quality of all included trials was determined based on the low risk of bias and the high quality of reported information (Jadad score ≥ 3). Meta-analysis of 293 eligible subjects showed that treatment with Nigella sativa improved the superoxide dismutase (SOD) level (48.18; 95% CI 30.29 to 66.08; p < 0.01), but there was no significant effect on the malondialdehyde (MDA) level (-5.32; 95% CI -1.19 to 0.128; p=0.114) and total antioxidant capacity (TAC) level (0.219; 95% CI -0.136 to 0.573; p = 0.227).

CONCLUSION

This meta-analysis suggests that Nigella sativa supplementation in humans may benefit as an antioxidant by increasing SOD levels but has no significant effect on the MDA level and TAC level.