Fenugreek (Trigonella foenum-graecum): A Review of Health Beneficial Physiological Effects

Fenugreek with reduced bitterness prevents diet-induced metabolic disorders in rats

Background

Various therapeutic effects of fenugreek (Trigonella foenum-graecum L.) on metabolic disorders have been reported. However, the bitterness of fenugreek makes it hard for humans to eat sufficient doses of it for achieving therapeutic effects. Fenugreek contains bitter saponins such as protodioscin. Fenugreek with reduced bitterness (FRB) is prepared by treating fenugreek with beta-glucosidase. This study has been undertaken to evaluate the effects of FRB on metabolic disorders in rats.

Methods

Forty Sprague–Dawley rats were fed with high-fat high-sucrose (HFS) diet for 12 week to induce mild glucose and lipid disorders. Afterwards, the rats were divided into 5 groups. In the experiment 1, each group (n = 8) was fed with HFS, or HFS containing 2.4% fenugreek, or HFS containing 1.2%, 2.4% and 4.8% FRB, respectively, for 12 week. In the experiment 2, we examined the effects of lower doses of FRB (0.12%, 0.24% and 1.2%) under the same protocol (n = 7 in each groups).

Results

In the experiment 1, FRB dose-dependently reduced food intake, body weight gain, epididymal white adipose tissue (EWAT) and soleus muscle weight. FRB also lowered plasma and hepatic lipid levels and increased fecal lipid levels, both dose-dependently. The Plasma total cholesterol levels (mmol/L) in the three FRB and Ctrl groups were 1.58 ± 0.09, 1.45 ± 0.05*, 1.29 ± 0.07* and 2.00 ± 0.18, respectively (*; P < 0.05 vs. Ctrl). The Hepatic total cholesterol levels (mmol/g liver) were 0.116 ± 0.011, 0.112 ± 0.006, 0.099 ± 0.007* and 0.144 ± 0.012, respectively (*; P < 0.05 vs. Ctrl). The calculated homeostasis model assessment as an index of insulin resistance (HOMA-IR) indicated 0.52 ± 0.04*, 0.47 ± 0.06*, 0.45 ± 0.05* and 1.10 ± 0.16, respectively (*; P < 0.05 vs. Ctrl). None of the FRB groups showed any adverse effect on the liver, kidney or hematological functions. In the experiment 2, no significant difference of food intake was observed, while the 1.2% FRB group alone showed nearly the same effects on glucose and lipid metabolism as in the experiment 1.

Conclusions

Thus we have demonstrated that FRB (1.2 ~ 4.8%) prevents diet-induced metabolic disorders such as insulin resistance, dyslipidemia and fatty liver.

Antidiabetic and neuroprotective effects of Trigonella foenum-graecum seed powder in diabetic rat brain

Trigonella foenum-graecum seed powder (TSP) has been reported to have hypoglycemic and hyperinsulinemic action. The objective of the study was to examine the antidiabetic and neuroprotective role of TSP in hyperglycemiainduced alterations in blood glucose, insulin levels and activities of membrane linked enzymes (Na+K+ATPase, Ca2+ATPase), antioxidant enzymes (superoxide dismutase, glutathione S-transferase), calcium (Ca2+) levels, lipid peroxidation, membrane fluidity and neurolipofuscin accumulation in the diabetic rat brain. Female Wistar rats weighing between 180 and 220 g were made diabetic by a single injection of alloxan monohydrate (15 mg/100 g body weight), diabetic rats were given 2 IU insulin, per day with 5% TSP in the diet for three weeks. A significant increase in lipid peroxidation was observed in diabetic brain. The increased lipid peroxidation following chronic hyperglycemia was accompanied with a significant increase in the neurolipofuscin deposition and Ca2+ levels with decreased activities of membrane linked ATPases and antioxidant enzymes in diabetic brain. A decrease in synaptosomal membrane fluidity may influence the activity of membrane linked enzymes in diabetes. The present study showed that TSP treatment can reverse the hyperglycemia induced changes to normal levels in diabetic rat brain. TSP administration amended effect of hyperglycemia on alterations in lipid peroxidation, restoring membrane fluidity, activities of membrane bound and antioxidant enzymes, thereby ameliorating the diabetic complications.

Study of lipid profile and parieto-temporal lipid peroxidation in AlCl₃ mediated neurotoxicity. Modulatory effect of fenugreek seeds

BACKGROUND

Peroxidation of lipid (LPO) membrane and cholesterol metabolism have been involved in the physiopathology of many diseases of aging brain. Therefore, this prospective animal study was carried firstly to find out the correlation between LPO in posterior brain and plasmatic cholesterol along with lipoprotein levels after chronic intoxication by aluminium chloride (AlCl₃). Chronic aluminum-induced neurotoxicity has been in fact related to enhanced brain lipid peroxidation together with hypercholesterolemia and hypertriglyceridemia, despite its controversial etiological role in neurodegenerative diseases. Secondly an evaluation of the effectiveness of fenugreek seeds in alleviating the engendered toxicity through these biochemical parameters was made.

RESULTS

Oral administration of AlCl₃ to rats during 5 months (500 mg/kg bw i.g for one month then 1600 ppm via the drinking water) enhanced the levels of LPO in posterior brain, liver and plasma together with lactate dehydrogenase (LDH) activities, total cholesterol (TC), triglycerides (TG) and LDL-C (Low Density Lipoproteins) levels. All these parameters were decreased following fenugreek seeds supplementation either as fenugreek seed powder (FSP) or fenugreek seed extract (FSE). A notable significant correlation was observed between LPObrain and LDL-C on one hand and LDHliver on the other hand. This latter was found to correlate positively with TC, TG and LDL-C. Furthermore, high significant correlations were observed between LDHbrain and TC, TG, LDL-C, LPObrain as well as LDHliver.

CONCLUSION

Aluminium-induced LPO in brain could arise from alteration of lipid metabolism particularly altered lipoprotein metabolism rather than a direct effect of cholesterol oxidation. Fenugreek seeds could play an anti-peroxidative role in brain which may be attributed in part to its modulatory effect on plasmatic lipid metabolism.

Metabolic and molecular action of Trigonella foenum-graecum (fenugreek) and trace metals in experimental diabetic tissues

Diabetes mellitus is a heterogeneous metabolic disorder characterized by hyperglycaemia resulting in defective insulin secretion, resistance to insulin action or both. The use of biguanides, sulphonylurea and other drugs are valuable in the treatment of diabetes mellitus; their use, however, is restricted by their limited action, pharmacokinetic properties, secondary failure rates and side effects. Trigonella foenum-graecum, commonly known as fenugreek, is a plant that has been extensively used as a source of antidiabetic compounds from its seeds and leaf extracts. Preliminary human trials and animal experiments suggest possible hypoglycaemic and antihyperlipedemic properties of fenugreek seed powder taken orally. Our results show that the action of fenugreek in lowering blood glucose levels is almost comparable to the effect of insulin. Combination with trace metal showed that vanadium had additive effects and manganese had additive effects with insulin on in vitro system in control and diabetic animals of young and old ages using adipose tissue. The Trigonella and vanadium effects were studied in a number of tissues including liver, kidney, brain peripheral nerve, heart, red blood cells and skeletal muscle. Addition of Trigonella to vanadium significantly removed the toxicity of vanadium when used to reduce blood glucose levels. Administration of the various combinations of the antidiabetic compounds to diabetic animals was found to reverse most of the diabetic effects studied at physiological, biochemical, histochemical and molecular levels. Results of the key enzymes of metabolic pathways have been summarized together with glucose transporter, Glut-4 and insulin levels. Our findings illustrate and elucidate the antidiabetic/insulin mimetic effects of Trigonella, manganese and vanadium.

The potential of fenugreek (Trigonella foenum-graecum) as a functional food and nutraceutical and its effects on glycemia and lipidemia

Dietary fiber from fenugreek blunts glucose and cholesterol after a meal and regulates the production of cholesterol in the liver. The mechanisms for these effects have not been fully elucidated. Fenugreek seeds contain 45.4% dietary fiber (32% insoluble and 13.3% soluble), and the gum is composed of galactose and mannose. The latter compounds are associated with reduced glycemia and cholesterolemia. Fenugreek's hypoglycemic effect has been especially documented in humans and animals with type 1 and type 2 diabetes mellitus. In addition, this dietary fiber has potential for widespread use in the food industry because its galactomannan composition has emulsifying and stabilizing properties. Flour supplemented with 8%-10% fenugreek dietary fiber has been used in the production of baked goods such as bread, pizza, muffins, and cakes. This application to flour allows for the production of functional foods that may be widely acceptable to consumers observing western diets.

Fenugreek seeds reduce atherogenic diet-induced cholesterol gallstone formation in experimental mice

Dietary hypocholesterolemic adjuncts may have a beneficial role in the prevention and treatment of cholesterol gallstones (CGS). In this investigation, fenugreek (Trigonella foenum-graecum) seed was evaluated for this potential on the experimental induction of CGS in laboratory mice. CGS was induced by maintaining mice on a lithogenic diet (0.5% cholesterol) for 10 weeks. Fenugreek seed powder was included at 5%, 10%, and 15% of this lithogenic diet. Dietary fenugreek significantly lowered the incidence of CGS in these mice; the incidence was 63%, 40%, and 10% in the 5%, 10%, and 15% fenugreek groups, respectively, compared with 100% in the lithogenic control. The antilithogenic influence of fenugreek is attributable to its hypocholesterolemic effect. Serum cholesterol level was decreased by 26%-31% by dietary fenugreek, while hepatic cholesterol was lowered by 47%-64% in these high cholesterol-fed animals. Biliary cholesterol was 8.73-11.2 mmol/L as a result of dietary fenugreek, compared with 33.6 mmol/L in high-cholesterol feeding without fenugreek. Cholesterol saturation index in bile was reduced to 0.77-0.99 in fenugreek treatments compared with 2.57 in the high-cholesterol group. Thus, fenugreek seed offers health-beneficial antilithogenic potential by virtue of its favourable influence on cholesterol metabolism.

Dietary fenugreek seed regresses preestablished cholesterol gallstones in mice

An animal study was carried out to evaluate the influence of dietary fenugreek seeds on regression of preestablished cholesterol gallstones (CGS). CGS was induced by feeding a high-cholesterol diet for 10 weeks. After CGS induction, the animals were maintained for a further 10 weeks on experimental diets of high cholesterol, 6% fenugreek powder, 12% fenugreek powder, or basal control. Incidence of CGS and its severity were evaluated at the end of this feeding regimen. The incidence of CGS was significantly lowered as a result of dietary fenugreek seeds, the extent of regression being 61% and 64% in the low and high dose groups compared with 10% regression in the basal control group. The antilithogenic influence of dietary fenugreek was accompanied by significant reductions of more than 35% in serum cholesterol concentration. Hepatic cholesterol concentration was also profoundly lowered by dietary fenugreek, being 53%–63% lower than that of the basal control diet. Biliary cholesterol concentration was significantly lower as a result of dietary fenugreek during the post-CGS induction period, resulting in a decreased cholesterol:phospholipid ratio (0.44 and 0.40 compared with 0.79 in the basal control group). Biliary cholesterol : bile acid ratio was lowered by 67% and 73% upon feeding fenugreek, significantly lower than that in the basal control group. The cholesterol saturation index in the bile was also beneficially lowered by fenugreek treatment during the post-CGS induction period (the index was 0.90 and 0.42 compared with 1.86 in the basal control group). The present study provides evidence of the potency of hypolipidemic fenugreek seeds in regressing preestablished CGS, and this beneficial antilithogenic effect is attributable to its primary influence on cholesterol levels. This finding is significant in the context of evolving a dietary strategy to address CGS, which could help in preventing the incidence and regression of existing CGS and controlling possible recurrence.