**6.4** *Nigella sativa* **toxicity**

*N. sativa* has GRAS status in the United States [74]. A randomized, placebocontrolled study with 40 healthy elderly investigated the safety profile after daily intake of 1 g *N. sativa* seed powder for 9 weeks. Results found no statistical changes in any of the biochemical markers of cardiac, liver, and kidney function [105]. In 70 patients with chronic renal disease, 2.5 ml/day *N. sativa* oil for 12 weeks was safe and effective in improving clinical and biochemical parameters of kidney function without adverse events [106]. In a clinical trial with obese women, *N. sativa* oil (which is present in whole seeds and polar seed extracts), reduced body weight, VLDL cholesterol and triglycerides [107]. Traditional toxicity studies in rodents have been performed. In mice, hepatotoxicity was observed after 14-days of oral dosing at 6–21 g/kg body weight of *N. sativa* seeds water extract. No signs of hepatotoxicity were observed with methanolic and chloroform extracts. Body weight reductions were seen in methanolic extracts [108]. Similar findings were observed with the water extract in rats with increases in serum gamma-glutamyl transferase and alanine aminotransferase, but no changes in alkaline phosphatase and degeneration of hepatocytes [109]. In another rat study, 1 g/day for 6 weeks of whole *N. sativa* seeds were protective against hyperlipidemia to a similar extent as simvastatin without adverse effects to liver markers [110]. Human equivalent doses are 30–100 g *N. sativa* extracts per day for the mice study, and 10 g whole seeds per day for the rat study [80].
