Herbs & Supplements:
Gamma Oryzanol

Principal Proposed Uses
  • Menopausal Symptoms ("Hot Flashes"), High Cholesterol
Other Proposed Uses
  • Anxiety, Stomach Distress, Bodybuilding

Gamma oryzanol is a mixture of substances derived from rice bran oil, including sterols and ferulic acid. It has been approved in Japan for several conditions, including menopausal symptoms, mild anxiety, stomach upset, and high cholesterol. Each year Japan manufactures 7,500 tons of gamma oryzanol from 150,000 tons of rice bran. Not surprisingly,most of the research on oryzanol has been performed in Japan.

Scientists are not certain how gamma oryzanol works. For menopause, it may affect a key hormone, luteinizing hormone (LH). Gamma oryzanol may also interfere with the absorption of cholesterol into the body from food, thus reducing cholesterol levels in the blood.

Sources

There is no daily requirement for gamma oryzanol.

Rice bran oil is the principal source of gamma oryzanol, but it is also found in the bran of wheat and other grains, as well as various fruits, vegetables, and herbs. However, to get enough gamma oryzanol to reach recommended therapeutic dosages, you will need to take supplements.

Therapeutic Dosages

The typical dosage of gamma oryzanol is 300 mg daily.

Therapeutic Uses

Despite the widespread use of gamma oryzanol for menopausal symptoms, the studies available provide little evidence that it is effective. The most commonly cited Japanese study was very small and did not have a control group.¹

Gamma oryzanol may be useful for elevated cholesterol, although the principal evidence appears to be limited to a few animal studies^2,3 as well as one small human trial using rice bran oil.⁴ No serious evidence has been presented for using gamma oryzanol as a treatment for anxiety or stomach distress.

Very preliminary evidence suggests that gamma oryzanol may increase endorphin release and aid muscle development.^5,6 These findings have created an interest in using gamma oryzanol as a sports supplement. However, the one reported double-blind study on this potential use did not find it effective..⁷

Safety Issues

No significant side effects have been reported with gamma oryzanol. However, the maximum safe dosages for young children, pregnant or nursing women, or those with severe liver or kidney disease have not been established.

Last reviewed March 2002 by Medical Review Board

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