NutriStack
Black Seed Oil and Fenugreek, a caution.
Both supplements are well-documented oral hypoglycemics in human trials. Taken concurrently, especially alongside antidiabetic medication (metformin, sulfonylureas, insulin), they can produce a larger-than-expected drop in blood glucose. The combination is not dangerous in healthy normoglycemic users, but in people actively managing diabetes or prediabetes it raises a real risk of additive hypoglycemia.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
Same shape as the other 1,729 pairs in the public database.
From the interaction database
What the row says.
Every entry follows the same shape: what is happening, the mechanism, the recommendation, and the primary literature.
At a glance
- Substances
- Black Seed Oil and Fenugreek
- Pair type
- Caution
- Evidence (highest tier)
- Moderate
- Source citations
- 4 sources
- Stack Score effect
- −5 to your Stack Score (per scored caution row).
- Scope
- Supplement × Supplement
- Last verified
- May 30, 2026
Caution · Moderate evidence
Caution
What is happening. Both supplements are well-documented oral hypoglycemics in human trials. Taken concurrently, especially alongside antidiabetic medication (metformin, sulfonylureas, insulin), they can produce a larger-than-expected drop in blood glucose. The combination is not dangerous in healthy normoglycemic users, but in people actively managing diabetes or prediabetes it raises a real risk of additive hypoglycemia.
Mechanism. Additive blood-glucose-lowering effect through overlapping pathways. Black Seed Oil (Nigella sativa, thymoquinone) lowers fasting glucose, postprandial glucose, and HbA1c in human RCTs by improving insulin sensitivity and beta-cell function. Fenugreek independently lowers glucose by slowing intestinal carbohydrate absorption (high soluble fiber, prolonged gastric emptying) and by enhancing insulin sensitivity and secretion (4-hydroxyisoleucine, trigonelline). Used together the glucose-lowering effects stack.
Recommendation. If you take both, monitor blood glucose more closely for the first 2 to 3 weeks, particularly if you are also on glucose-lowering medication. Typical doses studied are Black Seed Oil around 1 to 2.5 g/day and Fenugreek 5 to 10 g/day of seed (or standardized extract per label). Watch for hypoglycemia symptoms (shakiness, sweating, lightheadedness). Discuss with your prescriber before combining if you use insulin or a sulfonylurea, as medication doses may need adjustment. No specific timing separation is required.
Minimum separation. None required; effects are systemic and additive regardless of timing.
Sources (4)
- Reviews of Nigella sativa (black seed) and thymoquinone in human and animal studies report reductions in fasting glucose, postprandial glucose, and HbA1c via improved insulin sensitivity and beta-cell function.
- Meta-analyses of randomized controlled trials of Nigella sativa describe improved glucose homeostasis and serum lipids in type 2 diabetes.
- Systematic reviews and meta-analyses of fenugreek (Trigonella foenum-graecum) document significant lowering of fasting and postprandial glucose and HbA1c in people with diabetes and prediabetes.
- Pharmacology reviews of both botanicals describe overlapping glucose-lowering mechanisms, supporting an additive hypoglycemic effect when combined, especially with antidiabetic medication.
Stack Score
How this pair moves the number.
Effect on the composite score
If both Black Seed Oil and Fenugreek are in the same stack, this pair applies −5 to your Stack Score (per scored caution row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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