A very modest dose of Nigella sativa – known in the Middle East as Habbat ul Baraka or Habbat ul Sauda, and in Europe as black cumin – helps the body produce more insulin and also boosts the muscles’ sensitivity to insulin. Moroccan and Canadian researchers write about it in Evidence-Based Complementary and Alternative Medicine. If you read the animal study you may start to think that Nigella sativa might just be an extremely interesting supplement for anyone wanting to build muscle and lose body fat.
The researchers did a four-week experiment with a kind of desert rat – Meriones shawi – of which some were healthy and others produced insufficient insulin. Some of the diabetic desert rats were given metformin, a diabetes medicine, every day, and others were given an extract of Nigella sativa seeds.
The researchers made their extracts themselves. They used seeds from Morocco that had been dried and ground, and then extracted the active substances from this using ethanol. The human equivalent of the dose they administered to the desert rats would be about 400-700 mg per day. If you use dried seeds instead of an extract, then the amount would be about 20-25 g powder per day.
After four weeks the researchers gave the rats glucose, and they observed that the glucose levels of the diabetic rats that had been given Nigella sativa normalised more quickly than those of the diabetic rats that had not been given Nigella sativa.
NSE = diabetic rats, given Nigella sativa extract; DC = diabetic rats, given no supplements; NC = healthy rats, given no supplements.
Nigella sativa boosted the concentration of ‘good cholesterol’, HDL, and lowered the concentration of triglycerides, fats, in the blood. That would suggest that the extract reduces the risk of cardiovascular disease.
Administration of Nigella sativa boosted the insulin level [below left]. At the same time, the extract boosted the activity of the glucose transport protein GLUT4 [below right]. This meant the muscles became more sensitive to insulin and absorbed more nutrients from the bloodstream.
The figure below summarises how Nigella sativa probably works.
“Nigella sativa extract greatly improves systemic glucose homeostasis and HDL-cholesterol in diabetic Meriones shawi by acting through several mechanisms”, the researchers summarise. “Most importantly, Nigella sativa increases circulating insulin and enhances the sensitivity of peripheral tissues to the hormone. The latter effect can be attributed in part to an activation of the AMPK pathway in skeletal muscle and liver and to an increased content of Glut4 in skeletal muscle.”
“Such pleiotropic actions provide strong evidence in support of the traditional use of Nigella sativa seeds for the treatment of diabetes. They further call for high-quality clinical studies to determine the optimal conditions for complementary or alternative treatment in diabetic patients.”
The In Vivo Antidiabetic Activity of Nigella sativa Is Mediated through Activation of the AMPK Pathway and Increased Muscle Glut4 Content
The antidiabetic effect of N. sativa seed ethanol extract (NSE) was assessed in Meriones shawi after development of diabetes. Meriones shawi were divided randomly into four groups: normal control, diabetic control, diabetic treated with NSE (2 g eq plant/kg) or with metformin (300 mg/kg) positive control, both administered by daily intragastric gavage for 4 weeks. Glycaemia and body weight were evaluated weekly. At study’s end, an Oral Glucose Tolerance Test (OGTT) was performed to estimate insulin sensitivity. Upon sacrifice, plasma lipid profile, insulin, leptin, and adiponectin levels were assessed. ACC phosphorylation and Glut4 protein content were determined in liver and skeletal muscle. NSE animals showed a progressive normalization of glycaemia, albeit slower than that of metformin controls. Moreover, NSE increased insulinemia and HDL-cholesterol, compared to diabetic controls. Leptin and adiponectin were unchanged. NSE treatment decreased OGTT and tended to decrease liver and muscle triglyceride content. NSE stimulated muscle and liver ACC phosphorylation and increased muscle Glut4. These results confirm NSE’s previously reported hypoglycaemic and hypolipidemic activity. More significantly, our data demonstrate that in vivo treatment with NSE exerts an insulin-sensitizing action by enhancing ACC phosphorylation, a major component of the insulin-independent AMPK signaling pathway, and by enhancing muscle Glut4 expression.