Fenugreek: Background. Actions

2010

Historical Note

Fenugreek’s seeds and leaves are used not only as food but also as an ingredient in traditional medicine. It is indigenous to Western Asia and Southern Europe, but is now mainly cultivated in India, Pakistan, France, Argentina and North African countries. In ancient times it was used as an aphrodisiac by the Egyptians and, together with honey, for the treatment of rickets, diabetes, dyspepsia, rheumatism, anaemia and constipation. It has also been described in early Greek and Latin pharmacopoeias for hyperglycaemia and was used by Yemenite Jews for type 2 diabetes. In India and China it is still widely used as a therapeutic agent. In the United States, it has been used since the 19th century for postmenopausal vaginal dryness and dysmenorrhea.

Common Name

Fenugreek

Other Names

Trigonella seeds, bird’s foot, Greek hay, hu lu ba, methi, trigonella

Botanical Name / Family

Trigonella foenum graecum (family Leguminosae)

Plant Parts Used

Dried mature seed, although leaves are used less commonly.

Chemical Components

The main chemical constituents are fibre, tannicacid, fixed and volatile oils and a bitter extractive, steroidal saponins, flavonoids, polysaccharides, alkaloids, trigonelline, trigocoumarin, trigomethyl coumarin, mucilage (up to 30%), seven essential amino acids and vitamins A, C, D, B1, B2 and B3.

Main Actions

HYPOGLYCAEMIC

The hypoglycaemic effect of fenugreek seeds has been demonstrated in numerous studies involving experimentally induced diabetes (both type 1 and type 2) in rats, dogs, mice, rabbits and humans, and the effect has been described as slow but sustained. Interestingly, no reduction of fasting or postprandial blood sugar levels were observed in a placebo-controlled study in non-diabetic people who used a dose of 5 g/day over 3 months.

Fenugreek exerts its hypoglycaemic effect by delaying glucose absorption and enhancing its utilisation. Results from in vivo experiments suggest that fenugreek may increase the sensitivity of tissues to available insulin. The active component responsible for this activity is associated with a defatted part (non-lipid extract), rich in fibre-containing steroidal saponins and proteins.

ANTIULCEROGENIC ACTIVITY

Both an aqueous extract and a gel fraction isolated from the seeds demonstrated significant ulcer-protective effects in vivo. The seed fractions given orally to test animals provided dose-dependent gastric protection against the effects of ethanol that was as potent as that of omeprazole. Furthermore, histological studies found that the soluble gel fraction was significantly more protective than omeprazole. Preliminary research suggests that the polysaccharide composition and/or flavonoid components of the gel are responsible for the gastroprotective and antisecretory activities of the seeds.

HYPOCHOLESTEROLAEMIC EFFECT

Significant cholesterol-lowering activity has been demonstrated in several animal studies and human studies with diabetic volunteers. Although the mechanism of action is still unclear, it appears that the fibre and steroidal saponin content are important for activity.

IMMUNOSTIMULANT ACTIVITY

Enhanced humoral immunity, significant increases in macrophage activity and a stimulatory effect on lymphoproliferation have been demonstrated in vivo. Stimulatory effects were observed at 100 mg/kg and in some cases at 250 mg/kg.

ANTI-INFLAMMATORY AND ANTIPYRETIC ACTIVITY

Potent anti-inflammatory activity was demonstrated in an animal model for both single-dose and chronic-dose applications of a dried leaf decoction of fenugreek. The effectiveness of the 1000 mg/kg dose of the extract was relatively equal to 300 mg/kg sodium salicylate for single dosing; however, chronic administration was more effective than sodium salicylate. Additionally, the fenugreek decoction demonstrated stronger antipyretic activity than that of sodium salicylate.

ANTINOCICEPTIVE EFFECTS

Two studies in animal models have identified antinociceptive activity for fenugreek. This seems to be mediated through central and peripheral mechanisms. According to Javan et al (1997), the antinociceptive effects of 2000 mg/kg of the extract were more potent than 300 mg/kg sodium salicylate.

EFFECT ON THYROID HORMONES

Administration of fenugreek seed extract for 1 5 days to both mice and rats significantly decreased serum triiodothyronine (T3), suggesting that thyroxine (T4)-to-T3 conversion is inhibited and leads to increases in T4 levels.

STIMULATES DIGESTION

Traditionally, fenugreek is used to improve digestion. In vivo studies have identified that it enhances the activity of pancreatic and intestinal lipase, and sucrase and maltase thereby providing support to this traditional use.

Other Actions

Antineoplastic activity has been observed for fenugreek in the Ehrlich ascites carcinoma model in mice. Protodioscin, purified from fenugreek, has also exhibited antineoplastic activity on human leukaemia cell lines in vitro. Although fenugreek contains coumarin constituents, a placebo-controlled study found that it does not affect platelet aggregation, fibrinolytic activity or fibrinogen. Traditionally it is thought to promote lactation in nursing mothers and act as a general tonic.