BATON ROUGE, LOUISIANA. Researchers have investigated the possible cholesterol-lowering properties of rice bran, a by-product of milled rice. The team, from Pennington Biomedical Research Center, looked at rice bran oil and rice bran fiber separately, designing their study to exclude the effects of fatty acids. Rice bran products are frequently consumed in Japan and India, but not readily available in other countries. Earlier findings suggest that consuming rice bran oil can lower cholesterol levels as effectively as oat bran in individuals with moderately high cholesterol. Beneficial results have also been found for substituting rice bran oil for other types of cooking oil.
The present study consisted of two arms. The first arm involved 26 volunteers with borderline high cholesterol. Half were given defatted rice bran for five weeks to double their fiber intake. The rice bran did not lower overall blood cholesterol levels, and in fact it increased levels of low-density lipoprotein (LDL) cholesterol - the so-called "bad" cholesterol. Total cholesterol and other cardiovascular risk factors were unchanged. In the second arm, 14 volunteers followed two different diets for five weeks each. One was a diet in which rice bran oil made up a third of their total dietary fat; the other consisted of a blend of different oils with a similar fatty acid composition. After 10 weeks, total cholesterol had dropped significantly with rice bran oil. LDL cholesterol was reduced by 7 per cent and HDL cholesterol (the "good" form) was unchanged.
The researchers conclude that it is rice bran oil, and not the fiber, which helps lower cholesterol, despite the
fact that rice bran oil is high in saturated fatty acids. They suggest that the effect may be due to components
of the rice bran oil such as its unsaponifiable compounds, including plant sterols. Once the beneficial
compound is identified, the researchers believe that it could form part of an important functional food to help
protect against heart disease.