Gamma oryzanol is a mixture of ferulic acid esters of sterol and triterpene alcohols, and it occurs in rice bran oil at a level of 1-2%, although it has been extracted from corn and barley oils as well. It is theorized that some of the health benefits from rice bran oil, namely, its cholesterol-lowering effects, may be due to its gamma oryzanol content. Gamma oryzanol was first isolated and purified in the 1950s. In the 1960s, it was used medically in Japan for anxiety. 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. Gamma oryzanol is frequently sold as a bodybuilding aid, specifically to increase testosterone levels, stimulate the release of endorphins (pain-relieving substances made in the body), and promote the growth of lean muscle tissue. However, most currently available studies do not support these claims.