Gamma oryzanol is a naturally occurring mixture of plant chemicals called sterols and ferulic acid esters. Although it appears in grains such as barley and corn, gamma-oryzanol is extracted from rice bran oil for commercial purposes. Gamma oryzanol is actually two molecules in one. The largest part is the triterpenyl alcohol part. This is simply another name for sterol. Sterols are the group of compounds found throughout nature, with many vital biological functions. Some wellknown sterols are cholesterol and beta sitosterol. Many hormones such as testosterone, estrogen, progesterone, and corticosteroids, are derived from cholesterol, and can be thought of as modified sterols. The second half of each gamma oryzanol molecule is ferulic acid, a widespread plant compound.
Gamma oryzanol/ferulic acid is a potent membrane antioxidant in animals and humans. The role of antioxidants in exercise physiology has only recently been explored and elucidated. Several reviews have illustrated the mechanism by which anaerobic exercise actually produces free radicals, which result in fatigue. Surprisingly, the increased flow of oxygen to fuel working muscles is not a major source for free radical damage, as normal cellular antioxidant levels seem to be adequate for the amount of free radicals produced by oxidative processes. Instead, free radicals that overwhelm cellular defenses are produced by the action of xanthine oxidase on inosine in muscle tissue.
Apparently acting on the brain's control of digestion, and possibly through a direct effect on the stomach, gamma-oryzanol may help to ease heartburn and other digestive-system discomforts. Ulcer sufferers have taken it with some success. Gamma-oryzanol supplements have also relieved pain, nausea, vomiting, and other post-meal gastrointestinal symptoms in study participants suffering from gastritis (stomach inflammation). Japanese scientists conducting various trials have discovered that gamma-oryzanol may ease hot flashes and other symptoms of menopause, and may even help to lower cholesterol. In addition, antioxidant properties in the extract may protect heart vessels from free-radical damage.
Like other vegetable oils, rice bran oil appears to improve cholesterol profile as well as reduce heart disease risk in other ways. Weaker evidence suggests that the gamma oryzanol portion of rice bran oil can also improve cholesterol profile. It is thought to work by impairing cholesterol absorption in the digestive tract. Additionally, gamma oryzanol has antioxidant properties, although it is not clear that this implies any meaningful health benefits. Gamma oryzanol is used by some athletes based on early reports that suggested gamma oryzanol enhances muscle growth and sports performance. According to numerous websites, gamma oryzanol produces these benefits by increasing levels of testosterone, growth hormone, and other anabolic (muscle building) hormones.
Gamma oryzanol has also been advocated as a treatment for menopausal symptoms, but the basis of this potential use consists of evidence far too weak to be relied upon at all. In one study, gamma oryzanol injected into rats altered levels of circulation luteinizing hormone (LH). This in turn might conceivably help menopausal symptoms, but it is a long way from theoretical benefits in rats to proof of effectiveness in humans. One open study sometimes touted as direct evidence for benefit in menopause lacked a control group and therefore means nothing.