Gamma oryzanol is a substance derived from rice bran oil.[1] It is also found in wheat bran and some fruits and vegetables.
Gamma oryzanol is being consumed by bodybuilders due to its supposed anabolic effects. The compound is claimed to increase testosterone production and stimulate human growth hormone release, as well as improving strength during resistance exercise training. Fry, A. C. and associates [2] wanted to determine the effectiveness of gamma oryzanol (500 mg/day) supplementation in male bodybuilders. Placebo and gamma oryzanol groups both improved 1 repetition maximum muscular strength and vertical jump power but there were no differences between the groups. There were also no differences observed in circulating concentrations of hormones (testosterone, cortisol, estradiol, growth hormone, insulin), minerals or blood lipids. So after 9 weeks of training in combination with gamma oryzanol supplementation no ergogenic properties were noted.
Furthermore, scientific studies indicate that gamma oryzanol is poorly absorbed. It has been shown that less than 5% orally supplemented oryzanol is absorbed. When injected intravenously it actually induces anti-anabolic or catabolic activity (suppresses luteinizing hormone release, reduces growth hormone synthesis and release).[3] Another animal study showed that gamma oryzanol supplemented rats experienced significant increase in cholesterol excretion as well as 20% lower absorption.[4]
In short, gamma oryzanol appears to have no effect on hormone levels. Animal studies even suggest it might reduce testosterone levels [3].
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Refernences
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Sugano, M., and E. Tsuji. “Rice bran oil and human health.” Biomedical and Environmental Sciences 9 (1996): 242-246.
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Fry, A. C., et al. “The effects of gamma-oryzanol supplementation during resistance exercise training.” International journal of sport nutrition 7.4 (1997): 318.
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Wheeler, Keith B., and Keith A. Garleb. “Gamma oryzanol-plant sterol supplementation: metabolic, endocrine, and physiologic effects.” Int J Sport Nutr 1.2 (1991): 170-7.
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Seetharamaiah, G. S., and N. Chandrasekhara. “Effect of oryzanol on cholesterol absorption & biliary & fecal bile acids in rats.” The Indian journal of medical research 92 (1990): 471.
