Effects of Nigella sativa seeds (black cumin) on insulin secretion and lipid profile: a pilot study in healthy volunteers.
Br J Clin Pharmacol. 2019 Mar 15. Epub 2019 Mar 15. PMID: 30875097
Nigella sativa seeds (NSS), also known as black cumin, have been claimed to have antidiabetic and lipid-lowering properties. Our pilot study investigated the effects of powdered NSS on insulin secretion and lipid profile in healthy male volunteers. We conducted a double blind randomized placebo-controlled 4-week trial in 30 subjects, receiving NSS powder (1 g/day) or placebo orally (15 subjects/group). Insulin secretion as determined by the hyperglycemic clamp technique, insulin sensitivity as well as cholesterol and triglycerides serum concentrations, were measured before and after treatment. NSS powder administration was clinically well tolerated. It did not modify fasting glycemia and insulinemia, and was ineffective on glucose-induced insulin secretion and insulin sensitivity. No significant changes on serum lipids were observed after treatment in any treatment groups, nor between the two treatment groups. However, in the treated group only, there was a significant correlation between total-cholesterol change after treatment and its baseline level (r=-0.71, p=0.006, n=13), and between low-density lipoprotein (LDL)-cholesterol change after treatment and its baseline level (r=-0.74, p=0.004, n=13). No such correlations were found for high-density lipoprotein (HDL)-cholesterol, and for triglycerides. These results do not confirm any NSS effect on glucose regulation; however, they suggest that NSS powder may be of interest in lowering lipid concentrations in hyperlipidemic subjects.