Therapeutic applications of Fenugreek - Fenugreek

Alternative Medicine Review, Feb, 2003 by Ethan Basch, Catherine Ulbricht, Grace Kuo, Philippe Szapary, Michael Smith

Abstract

Fenugreek has a long history of medical uses in Ayurvedic and Chinese medicine, and has been used for numerous indications, including labor induction, aiding digestion, and as a general tonic to improve metabolism and health. Preliminary animal and human trials suggest possible hypoglycemic and antihyperlipidemic properties of oral fenugreek seed powder.

(Altern Med Rev 2003;8(1):20-27)

Historical Uses of Fenugreek

Fenugreek (Trigonella foenum-graecum L. Leguminosae) is one of the oldest medicinal plants, originating in India and Northern Africa. An annual plant, fenugreek grows to an average height of two feet. The leaves and seeds, which mature in long pods, are used to prepare extracts or powders for medicinal use. Applications of fenugreek were documented in ancient Egypt, where it was used in incense and to embalm mummies. In modern Egypt, fenugreek is still used as a supplement in wheat and maize flour for bread-making. (1) In ancient Rome, fenugreek was purportedly used to aid labor and delivery. In traditional Chinese medicine, fenugreek seeds are used as a tonic, as well as a treatment for weakness and edema of the legs. (2) In India, fenugreek is commonly consumed as a condiment (2) and used medicinally as a lactation stimulant. (3) There are numerous other folkloric uses of fenugreek, including the treatment of indigestion and baldness. The possible hypoglycemic and antihyperlipidemic properties of oral fenugreek seed powder have been suggested by the results of preliminary animal and human trials.

Active Constituents

The fraction of fenugreek that contains the testa (i.e., the portion of the fenugreek seed with the peculiar smell and bitter taste) and the endosperm of the defatted seeds (i.e., the "A" subfraction) are thought to be associated with the hypoglycemic effects of fenugreek. These effects have not been observed in studies of lipid extracts. (4,5) It is possible fenugreek lowers lipids because it contains saponins that are transformed in the gastrointestinal tract into sapogenins. Fenugreek seeds contain 50-percent fiber (30-percent soluble fiber and 20-percent insoluble fiber) that can slow the rate of postprandial glucose absorption. This may be a secondary mechanism for its hypoglycemic effect.

Mechanisms of Action

The hypoglycemic effects of fenugreek have been attributed to several mechanisms. Sauvaire et al demonstrated in vitro the amino acid 4-hydroxyisolcucine in fenugreek seeds increased glucose-induced insulin release in human and rat pancreatic islet cells. (6) This amino acid appeared to act only on pancreatic beta cells, since the levels of somatostatin and glucagon were not altered. In human studies, fenugreek reduced the area under the plasma glucose curve and increased the number of insulin receptors, although the mechanism for this effect is unclear. (7) In humans, fenugreek seeds exert hypoglycemic effects by stimulating glucose-dependent insulin secretion from pancreatic beta cells, (8) as well as by inhibiting the activities of alpha-amylase and sucrase, (9) two intestinal enzymes involved in carbohydrate metabolism.

Fenugreek seeds also lower serum triglycerides, total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C). (10-14) These effects may be due to sapogenins, which increase biliary cholesterol excretion, in turn leading to lowered serum cholesterol levels. (10-15-17) The lipid-lowering effect of fenugreek might also be attributed to its estrogenic constituent, indirectly increasing thyroid hormone [T.sub.4].

Fenugreek in the Treatment of Diabetes Type 2 Diabetes

In animal and several small, human trials, fenugreek seeds have been found to lower fasting serum glucose levels, both acutely and chronically.

Gupta et al reported the results of a small randomized, controlled, double-blind trial to evaluate the effects of fenugreek seeds on glycemic control. (18) Twenty-five patients with newly diagnosed type 2 diabetes received either 1 g daily of a hydroalcoholic extract of fenugreek seeds or "usual care" (dietary discretion and exercise). After two months, mean lasting blood glucose levels were reduced in both groups without significant differences between groups (148.3 mg/dL to 119.9 mg/dL in the fenugreek group versus 137.5 mg/dL to 113.0 mg/dL in the "usual care" group). There were no significant differences between groups in mean glucose tolerance test values at the study's end. The authors did note differences between groups in the area under the curve for blood glucose and insulin levels. This study suggests that fenugreek seed extract and diet/exercise may be equally effective strategies for attaining glycemic control in type 2 diabetes. However, the trial may have been too small or brief to detect significant mean differences between groups. In addition, it is not clear if mean glucose values would have normalized without intervention, and design and methods were not well described, which limits the clinical relevance of these results.

Raghuram et al reported the results of a randomized, controlled, crossover trial of fenugreek seeds in 10 patients with type 2 diabetes. (7) The doses of these patients' antidiabetic drug, glibenclamide, ranged from 2.5-7.5 mg per day; both medication dose and dietary intake were stabilized prior to the actual study periods. The patients were given either 25 g powdered fenugreek seeds in two equal doses with meals or meals without fenugreek supplementation for 15 days. The fenugreek powder was added to the experimental diet in the form of dietary fiber, resulting in higher fiber content in the experimental diet than in the control diet. Five diabetic patients were randomized to receive fenugreek during the first 15-day period; the other five received it during the second period. Subjects were then crossed over an additional 15 days with no washout period. In the fenugreek-treated patients, statistically significant mean improvements were reported for glucose-tolerance test scores and serum-clearance rates of glucose (control group, 153 [ or -] 11.92 mg/mL/min; fenugreek group, 136.4 [ or -] 6.36 mg/mL/min). The absolute difference in glucose between the two groups was not mentioned. Larger studies with washout periods are needed to confirm these results.