DEAR DR. BLONZ: I have some questions regarding rice oil and peanut oil. I like to use them for cooking because of their health benefits and flavors. I know that peanut oil has to be stored in the refrigerator, and read the same thing about rice oil; however, at the Asian market where I purchase my rice oil, the proprietor just keeps it in her cupboard. Who is correct? -- K.K., San Diego
DEAR K.K.: Rice oil, usually called rice bran oil, has many healthful attributes. It contains healthful fatty acids, but there are also some nonfat components that are receiving some attention. The phytochemicals of note include the tocopherols and tocotrienols (vitamin E and its relatives), and certain triterpene alcohols, most notably a compound named gamma oryzanol.
A study in the January 2005 issue of the American Journal of Clinical Nutrition compared the cholesterol-lowering abilities of rice bran oil to those of rice bran (without the oil). The study used a diet in which 1/3 of the fats were from rice bran oil. The control group used other foods with similar levels of monounsaturated, polyunsaturated and saturated fats as that found in rice bran oil. After the 10-week experimental period, the rice bran oil group experienced a significant decrease in LDL cholesterol -- the one you want to lower -- of 7 percent.
A companion study looked to see whether adding rice bran, without the oil, would also have a cholesterol-lowering effect. The control group had 17 grams of fiber a day, while the experimental group had an equal amount of rice bran (no oil) added to their daily regimen so they had twice the intake of fiber per day. The study found no impact on cholesterol levels from the bran.
From these studies, the scientists concluded that it wasn't the fats in the rice bran oil, but its unique nonfat phytochemicals that were most likely to have been responsible. This is a theme we continue to see throughout nature.
Rice bran oil is also a great cooking oil because it has a very high smoke point -- the temperature at which an oil will begin to break down -- of 490 degrees. This means it can handle high-heat processes such as frying without giving off the acrid smoke that oils with lower smoke points might.
Similar to whole grains, oils are perishable. Purchase only the amount that you'll use within 4 to 6 months, and store in a well-sealed container in a cool place out of direct light. As long as it does not sit on the shelf for too long, refrigeration is not essential for rice bran oil or peanut oil, but it certainly works in your favor and does not harm the oil in any way.
Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.