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

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.

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).

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.

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