New research findings point to the specific component of rice bran responsible for its heart-healthy effects. Two small studies show that it is the oil, and not the fiber, that helps lower cholesterol. According to researchers at the Pennington Biomedical Research Center in Baton Rouge, the findings provide evidence that plants contain compounds beneficial to our health.
Previous research has also pointed to the heart-healthy effects of rice bran and rice bran oil, which is most commonly available in Japan and India, but may also be found in some specialty food stores in the United States.
One study found that adding rice bran to the diet of people with moderately high cholesterol lowered cholesterol levels just as effectively as an oat bran-containing diet did. Another study found that middle age and elderly study participants who substituted rice bran oil for their usual cooking oils experienced decreases in their cholesterol levels.
In the first study, 26 men and women were randomly assigned to a low-fiber diet, in which they consumed up to 22 grams of fiber per day, or a high-fiber diet with defatted rice bran, in which they consumed twice as much fiber as the other group. The defatted rice bran was used in muffins, cookies and breads. At the end of the five-week study, none of the patients experienced great changes in their overall blood cholesterol levels. An unexpected finding was that subjects in the defatted rice bran group had higher levels of low-density lipoprotein (LDL) cholesterol -- the artery-clogging "bad" cholesterol.
In the second study, 14 participants followed two different diets for five weeks each. During the first five-week period the study participants consumed one third of their total daily dietary fat in the form of a blend of peanut oil, olive oil, corn oil, canola oil, palm oil and butter. During the second five-week period, the oil blend was replaced with rice bran oil.
The oil blend had a fatty acid composition similar to that found in rice bran oil, the researchers note. Rice bran is high in saturated fatty acids, which has been shown to have deleterious effects on cholesterol levels. Thus, a diet consisting of rice bran oil would not be expected to lower cholesterol, Most said.
At the end of the study, however, Most and her team found that the study participants' cholesterol levels -- LDL cholesterol in particular -- were lowest when their diet consisted of rice bran oil.
The findings from both studies show that it is the rice bran oil, and not the fiber, that lowers blood lipids in people with borderline high total cholesterol.
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