Herb-Drug Interactions: Fenugreek

Trigonella foenum-graecum L. (Fabaceae)

Synonym(s) and related species

Bird’s foot, Bockshornsame, Foenugreek, Greek hay.

Not to be confused with Bird’s foot trefoil, which is Lotus corniculatus.

Pharmacopoeias

Fenugreek (European Ph, 6th ed., 2008 and Supplements 6.1, 6.2, 6.3 and 6.4).

Constituents

Fenugreek seeds are about 25% protein (particularly lysine and tryptophan) and about 50% mucilaginous fibre. The seeds also contain flavonoids (luteolin, quercetin and vitexin). Saponins, natural coumarins and vitamins (nicotinic acid) are also present.

Use and indications

The seeds of fenugreek have been used as an appetite stimulant and for digestive disorders (including constipation, dyspepsia and gastritis). It has also been used in respiratory disorders and is said to be an expectorant. Topically, fenugreek has been used for wounds and leg ulcers, and as an emollient. It has been reported to have hypocholesterolaemic and hypoglycaemic activity.

Pharmacokinetics

No relevant pharmacokinetic data found. For information on the pharmacokinetics of individual flavonoids present in fenugreek, see under flavonoids.

Interactions overview

Fenugreek saponins may modestly enhance the antidiabetic effects of the sulfonylureas. For a case report describing a raised INR in a patient taking a herbal medicine containing boldo and fenugreek, see Boldo + Warfarin and related drugs9. For information on the interactions of individual flavonoids present in fenugreek, see under flavonoids.

Fenugreek + Antidiabetics

In one study, fenugreek saponins had modest additional antidiabetic effects when they were added to established treatment with sulfonylureas.

Clinical evidence

Fenugreek seed appears to have been widely studied for its blood-glucose-lowering properties; however, studies on its effects in combination with conventional treatments for diabetes appear limited. In one randomised study, 46 patients taking sulfonylureas (not named), with fasting blood-glucose levels of 7 to 13mmol/L, were given fenugreek saponins 2.1 g three times daily after meals for 12 weeks. When compared with 23 similar patients given placebo it was found that fenugreek saponins decreased fasting blood-glucose levels by 23% (8.38mmol/L versus 6.79mmol/L). Diabetic control was also improved: glycosylated haemoglobin levels were about 20% lower in the treatment group (8.2% versus 6.56%). The fenugreek saponin preparation was an extract of total saponins of fenugreek given as capsules containing 0.35 mg per capsule, equivalent to 5.6 g of crude fenugreek.

Experimental evidence

The blood-glucose-lowering activity of fenugreek and its extracts has been well studied in animal models; however, there appear to be no data directly relating to interactions.

Mechanism

It is suggested that fenugreek decreases blood-glucose levels by affecting an insulin signalling pathway.

Importance and management

Evidence on the use of fenugreek with conventional antidiabetic medicines appears to be limited to this one study, which suggests that fenugreek may have some modest additional blood-glucose-lowering effects to those of the sulfonylureas. As these modest effects were apparent over a period of 12 weeks it seems unlikely that a dramatic hypoglycaemic effect will occur.

Fenugreek + Food

No interactions found. Fenugreek is often used as a flavouring in foodstuffs.

Fenugreek + Herbal medicines

No interactions found.

Fenugreek + Warfarin and related drugs

For a case report describing a raised INR in a patient taking a herbal medicine containing boldo and fenugreek, see Boldo + Warfarin and related drugs.