Athletes use many nutritional supplements to improve their performance regardless of nutritional status.1 Therefore, interest in safer nutritional therapies and supplements for muscle building and performance enhancement is rising.
All performance enhancing supplements are regulated by the World Anti-Doping Code as defined by theWorld Anti-Doping Agency.2–5 Many traditional herbal medicines are being investigated as safer alternatives for their nutritional benefits and performance enhancement. However, they need to be scientifically evaluated for their efficacy and safety in the relevant populations using standardized procedures such as randomized double-blind placebo controlled studies.6,7
Fenugreek, Trigonella foenum-groecum L. (Fabaceae) seeds extract is a component of many nutritional dietary products that are recommended for athletes and exercising male subjects. Fenugreek seeds, a spice and food grain, has traditional history of medicinal use in the management of type 2 diabetes mellitus in Egypt, Southern Europe, India, Asia, and North Africa.8 Fenugreek seeds extract is certified as a GRAS (generally recognized as safe) item under clause §182.20 (essential oils, oleoresins and natural extractives including distillates) by the US Food and Drug Administration.
Traditionally, fenugreek seeds have been reported to be useful in hormonal regulation, in particular for male impotence and as a galactagogue in lactating mothers.9 In India, ground fenugreek seeds mixed with jaggery are recommended for females after childbirth for their anabolic effects to develop andstrengthen muscles.10 Recent studies on fenugreek seeds extracts support their effectiveness in promoting lean body mass, and lowering cholesterol.11 Fenugreek extract is reported to enhance endurance capacity and the utilization of fatty acids as an energy source in male mice.12 One recent study on fenugreek extract reported fat reducing effects greater than placebo in young, healthy resistance-exercising males.13 These effects are purported to be mediated through an aromatase and 5α reductase inhibition, thereby increasing total testosterone levels by blocking its conversion to estrogen and dihydrotestosterone, respectively.13 Increased testosterone levels are known to increase muscle size and strength in men14 with downstream benefits on body weight, body fat, muscle size, strength, libido, energy, and mood.15,16 Increased total testosterone levels could potentially affect serum free/bioavailable testosterone concentrations, resulting in escalated delivery and use by muscle cells to enhance protein synthesis, thus positively influencing strength and body fat. However, direct evidence for the androgenic effects of fenugreek seeds extract or its components in clinical practice is lacking.
Fenugreek seeds are rich in steroidal compounds like glycosides and saponins including diosgenin, yamogenin, gitogenin, tigogenin, and neotigogens. Diosgenin is an important precursor for the synthesis of a number of sex hormones.17 Diosgenin, a steroidal sapogenin, is reported to augment overall weight and muscle growth in rats.18 Moreover, diosgenin is reported to improve glucose metabolism by promoting adipocyte differentiation and inhibiting inflammation in adipose tissues.19 We have previously shown the efficacy of the glycoside fraction of fenugreek seeds (Fenu-FG) on testosterone levels in immature castrated male rats.20 Recently, the excellent safety profile of sub-chronic (90-day) administration of Fenu-FG without any effects on body weight has been demonstrated in rats.21
Taking clues from both traditional and modern literature regarding the androgenic potential and safety of fenugreek glycosides, the present pilot study investigated furostanol glycosides-based fenugreek seeds extract (Fenu-FG) supplementation using a prospective, randomized, double blind, placebo-controlled design in healthy male subjects during an 8-week resistance training programme.
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