Nigella sativa

When looking at the human evidence in particular, nigella sativa appears to have a general health protective effect of a very small magnitude. It is able to reduce triglycerides and glucose when elevated and can normalize cholesterol metabolism (although not HDL-C) as well, but the amount of benefit it confers is too small for it to be considered a good intervention. As a general antiinflammatory agent (such as its usage in rheumatoid arthritis) it also seems modestly effective.

It does appear to have more promise as an immune booster (no evidence on rates of sickness, but it appears to increase the ability of macrophages to attack invaders) and an anti-allergic compound (with efficacy against allergic rhinitus, asthma, and eczema). One study that used nigella sativa alongside a proton pump inhibitor noted that the seed extract was potently anti-bacterial against heliobacter pylori with a comparable potency to the reference drugs used.

Although much more evidence is needed on this last claim, in men with central obesity the seeds have been noted to greatly improve subjective symptoms of obesity. Symptoms such as loss of libido (affected 84% of men), forgetfulness (89%), high appetite (73%), aches and arthalgia (74%), sleeplessness (54%), and laziness (74%) amongst others were noted to be outright abolished despite no changes in placebo.

Supplementation of the seeds of nigella sativa usually use the basic seed extract (a crushed powder of the seeds with no further processing or concentration) or the seed oil, both of which do not require a large degree of processing as the medicinal dosage is close to the raw product's natural state.

While 1 gram of the seed tends to always underperform relative to 2-3 grams, there is not sufficient evidence to suggest which of those two higher doses is 'better' and thus something within that range is recommended.

As the seeds are about a quarter to one third fatty acids (ie. the seed oil) then supplementation of any black seed oil product would be 3-4 times lower than the aforementioned range (giving a recommended range of 250-1,000 mg daily).

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what effects nigella sativa has on your body, and how strong these effects are.

Grade	Level of Evidence [show legend]
	Robust research conducted with repeated double-blind clinical trials
	Multiple studies where at least two are double-blind and placebo controlled
	Single double-blind study or multiple cohort studies
	Uncontrolled or observational studies only

Level of Evidence ? The amount of high quality evidence. The more evidence, the more we can trust the results.	Outcome	Magnitude of effect ? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.	Consistency of research results ? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.	Notes
	Blood Pressure	Minor	Moderate See all 4 studies	The reduction in blood pressure is only seen in hypertensives and very mild (1-3mmHg), likely not practically relevant at all.
	LDL-C	Minor	Moderate See all 8 studies	Reductions in LDL-C are mild at best and only occur in persons with impaired lipid profiles (high cholesterol or dyslipidemia), but they do appear to occur with ingestion of the seed extract
	Total Cholesterol	Minor	Moderate See all 8 studies	Decreases have been sporadically noted in persons with high cholesterol initially, the cholesterol reductions are mild at best and do not affect persons with normal cholesterol.
	Triglycerides	Minor	Moderate See all 8 studies	The decreases in triglycerides only affect those with high triglycerides, and the decrease scales with severity of hyperlipidemia (mild elevation of TGs is met with a 1-5% decrease, significantly elevated TGs are met with a 15-20% reduction).
	Weight	Minor	Low See all 4 studies	One study has noted weight loss, but due to the reduction in appetite and no records of food intake the possibility of subjects losing weight due to eating less cannot be ruled out. Other studies have failed to find an influence of treatment.
	HDL-C	-	Very High See all 8 studies	Mild increases have been reported in some cases, but for the most part nigella sativa does not influence HDL cholesterol in the active dosage range.
	Liver Enzymes	-	High See all 5 studies	There may be a reducing effect in instances of liver damage (this curative effect needs to be explored more), and there are no alterations in liver enzymes that would be indicative of liver damage.
	Allergies	Notable	Very High See all 4 studies	Supplementation of the seed appears to beneficially influence most symptoms associated with allergies and most causes of the allergies (rhinitus, eczema, asthma, etc.), with the magnitude being somewhat notable among supplements.
	Subjective Well-Being	Notable	- See study	Although only based on one study, in men with central obesity and a wide variety of general health complaints supplementation has outright abolished all measured complaints such as loss of libido, high appetite, pain, and forgetfulness.
	Appetite	Minor	- See study	The side-effect of 'high appetite' was effectively abolished in men with central obesity, which may underlie the observed weight loss; food intake was not reported in this study.
	Attention	Minor	- See study	Attention processing on trail making tests appears to be increased.
	Cognition	Minor	- See study	A slight improvement in cognition has been noted with supplementation of nigella seed extract in older persons
	Memory	Minor	- See study	There appears to be a small but respectable (15-20% higher than baseline) improvement in logical memory and 30 minute recall in older subjects supplementing the seeds in their daily lifestyle.
	Nasal Congestion	Minor	- See study	Nasal congestion as a side-effect of allergic rhinitus is slightly reduced following the treatment of rhinitus with nigella sativa seeds
	Pain	Minor	- See study	Pain as a side-effect of rheumatoid arthritis is modestly reduced.
	Processing Speed	Minor	- See study	Trail making test time in older adult men appears to be reduced modestly with daily supplementation of nigella seed extract
	Pulmonary Function	Minor	Very High See 2 studies	While the magnitude of benefit has not yet been compared to reference drugs, nigella sativa extracts appear to benefit lung function in both asthmatics and persons with otherwise damaged lung function; no studies in otherwise healthy persons.
	Seizure Frequency	Minor	- See study	Seizure frequency in children with poorly controlled epilepsy is significantly reduced with a seed extract, and while it was quite notable in some children it was variable enough to also be quite modest in others. Needs more research to assess potency.
	Serum Albumin	Minor	Moderate See all 3 studies	An increase in serum albumin has been noted, and the reason for this currently unknown.
	Symptoms of Rheumatoid Arthritis	Minor	- See study	A modest reduction in symptoms of rheumatoid arthritis (9%) has been noted with ingestion of the seeds
	Adiponectin	-	- See study	No significant influence on adiponectin concentrations
	Bilirubin	-	Very High See 2 studies	Despite treating the viral load of hepatitis C, no significant changes in serum bilirubin exist.
	Blood Glucose	-	Very High See all 5 studies	Although the best evidence to date shows no change in blood glucose, these studies were not structured to assess the influence on diabetics; in diabetics, there appears to be a significant reduction in glucose.
	C-Reactive Protein	-	- See study	The alterations in C-reactive protein failed to reach statistical significance, but are otherwise not very well explored.
	Creatinine	-	Very High See 2 studies	No significant influence on serum creatinine
	Food Intake	-	- See study	No significant alterations in food intake associated with ingestion of nigella sativa.
	Free Testosterone	-	- See study	No significant influence on circulating free testosterone concentrations in men with central obesity
	Heart Rate	-	- See study	No significant influence on heart rate or pulse rate.
	Processing Accuracy	-	- See study	No significant improvements in the accuracy of cognitive processing appears to occur with supplementation of nigella sativa seeds.
	Proteinuria	-	- See study	No significant influence on the rate of proteinuria, suggesting no kidney damage associated with supplementation.
	Uric Acid	-	Moderate See 2 studies	No statistically significant alterations in uric acid concentrations in serum
	Working Memory	-	- See study	Despite improvements in logical memory and 30 minute recall, digit span tests are not affected by supplementation of nigella sativa.
	Viral Load	Notable	- See study	A pilot study in hepatitis C noted that the viral load was reduced to 38.6% of baseline with a modest dosage of the seed oil, a fairly drastic reduction.
	Asthma	Minor	Very High See 2 studies	Asthmatic symptoms appear to be reduced with supplementation of nigella sativa seeds, in part due to benefits to lung function and in part due to its anti-allergic properties. Potency has not been adequately assessed
	HbA1c	Minor	- See study	A mild decrease in HbA1c has been noted in diabetics given the seeds as an adjuvant to standard therapy
	Immunity	Minor	- See study	Macrophage phagocytic activity and killing potential is increased following oral ingestion of the seed extract.
	Red Blood Cell Count	Minor	- See study	A normalization of RBC count has been noted in the treatment of hepatitis C with the seed oil of nigella sativa
	White Blood Cell Count	Minor	- See study	A normalization of WBC count has been noted in persons with hepatitis C being treated with the seed oil.
	Cortisol	-	- See study	No significant alterations in cortisol concentrations seen with supplementation of the seeds.

Studies Excluded from Consideration

• Pharmacokinetic study^[1]

• Confounded with Phyllanthus niruri^[2]

• Confounded with pharmaceuticals^[3][4]