Healthy Oil Products From Thailand, Rice Bran Oil

Author: Michihiro Sugano and Etsuko Tsuji 

Dietary fat is a crucial factor in the regulation of plasma cholesterol levels, and there is overwhelming evidence to support the hypocholesterolemic effect of vegetable oils that are rich in polyunsaturated fatty acids, mainly linoleic acid. Rice bran oil (RBO) is not a popular oil worldwide, but it is in steady demand as a so-called “healthy oil” not only in Japan but also in Asian countries, particularly India. Approximately 80 thousand tons of RBO, corresponding to only 3.5% of total vegetable oils, is consumed annually in Japan.

A number of studies in humans and animals have shown that RBO is as effective as other vegetable oils in lowering plasma cholesterol levels. In some cases, RBO lowered plasma cholesterol more effectively than other commonly used vegetable oils rich in linoleic acid; this effect can be attributed to the occurrence of specific components in RBO, -oryzanol (and its constituents, triterpene alcohols) and perhaps tocotrienols.

A range of human and animal studies have shown that rice bran oil (RBO) is an edible oil of preference for improving serum cholesterol levels and lipoprotein profiles with similarity to the more commonly used vegetable oils such as corn oil and safflower oil. Of particular interest is the observation that blending RBO with safflower oil at a definite proportion (7:3, wt/wt) magnifies the hypocholesterolemic efficacy, compared with the effect of each oil alone. Although the mechanism underlying this effect is not apparent at present, the blending may have a practical significance. The blending effect was reproduced in rats fed a cholesterol-enriched diet, and there was also a decrease in liver cholesterol. The occurrence of peculiar components such as -oryzanol and tocotrienols could be responsible for the hypocholesterolemic effect of RBO.