Does black seed oil work as a supplement?

In people with type 2 diabetes, black seed supplementation shows a meaningful effect on blood sugar. Fasting blood sugar dropped by an average of 21 mg/dL, and the long-term blood sugar measure (HbA1c) fell by an average of 0.44 percentage points. This effect was most pronounced with use lasting longer than 8 weeks for blood sugar, and with higher doses (more than 1 gram per day) and the oil form for HbA1c. LDL cholesterol and total cholesterol also fell clearly (by an average of 19.5 and 18.8 mg/dL, respectively). No demonstrable effect was found on triglycerides, 'good' HDL cholesterol, body weight, or BMI.

Blood pressure dropped slightly but measurably with the use of black seed in powder form: systolic by an average of 3.3 mmHg and diastolic by 2.8 mmHg. For the oil form, this effect was less clear. The longer-term effects remain unknown.

For other conditions, such as cancer or cardiovascular disease, the evidence in humans has not yet been established. Laboratory research shows that the active compound in black seed can inhibit the growth of breast cancer cells and can enhance the effect of a chemotherapy agent. But such cell culture results say nothing about what happens in the human body. The step from the laboratory to practice is large and has not yet been taken.

There is a documented report of serious side effects following the ingestion of black seed oil: muscle damage, acute kidney failure, and liver damage in the same individual. These are rare but serious risks. This concerns a single case, so the exact probability is unknown, but it is a clear safety signal. If you already have kidney, liver, or muscle problems, discuss use with your doctor first.