5/17/2005 - A natural component of rice bran oil lowers cholesterol inrats, and ongoing research also shows it may have potential as ananti-cancer and anti-infection agent in humans, according to a Universityof Rochester scientist who has studied the antioxidant since 1996.

The latest findings from Mohammad Minhajuddin, Ph.D., and colleagues, arereported in the May 2005 Food and Chemical Toxicology journal. They showthat total cholesterol levels in animals dropped by 42 percent, and LDL or"bad cholesterol" levels dropped up to 62 percent, after their diets weresupplemented with a concentrated form of Vitamin E called tocotrienol richfraction or TRF isolated from rice bran oil.

Vitamin E, which has been widely studied for its health benefits, consistsof both tocopherols and tocotrienols. Much research has focused on thetocopherols derived from corn, wheat and soybean. But the tocotrienols(TRF) seem to have greater antioxidant properties and are becoming morenoteworthy in scientific research, Minhajuddin says. TRF is derived frombarley, oats, palm and rice bran.

The best form of TRF comes from rice bran oil, which is contained in theouter grain hull of rice. Its properties inhibit the activity of HMG-CoAreductase, an enzyme involved in cholesterol biosynthesis. However, sincetaking any form of Vitamin E for a long time can be harmful, the purposeof Minhajuddin's latest reported research was to find the minimum dose ofTRF that provided the maximum antioxidants and effectively loweredcholesterol.

The results: The most effective dose in rats was 8 IU kg/day. Extrapolatedto humans, a person with an average body weight of 154 pounds would getaround 560 IU, which is close to the 400 IU of Vitamin E normally taken.(The upper tolerable intake of Vitamin E is 1500 IU).

Researchers have been investigating natural ways (besides diet andexercise) to achieve lower cholesterol levels, despite the popularity andeffectiveness of statin drugs. Although millions of Americans take statinsand do well, they are expensive and they come with side effects. So far,scientists have not found any adverse effects of tocotrienols, saysMinhajuddin, a research associate in the Department of Pediatrics.

Minhajuddin, who is from India, also has preliminary, unpublished datafrom a study he conducted in that country, showing that TRF reducescholesterol in humans as well as in animals. Five healthy volunteers withtotal cholesterol levels in the "normal" range of 170-230 mg/dL, whoingested TRF in capsule form at a dose of 8 IU kg/day for four weeks, sawtheir cholesterol levels drop by 10 percent with a 26-percent decline inLDL-cholesterol levels. A case study of a 5-year-old boy in India, who hada genetic defect (familial hypercholesterolemia) that caused his totalcholesterol to climb to 440 mg/dL, resulted in a 20-percent decline afterabout two months of tocotrienol supplements. The boy's cholesterol didrise again, however, after 100 weeks of TRF supplements.

In addition, Minhajuddin and colleagues previously showed in animals thatTRF reacts with liver enzymes in such a way that it clears toxicsubstances from the organ, and reduces or stabilizes liver tumors. Thegroup concluded that long-term use of tocotrienol might reduce overallcancer risk, according to published research last year in the EuropeanJournal of Cancer Prevention. Currently, Minhajuddin's research group isusing a scientific model to study infection and the immune system, and howto regulate the expression of a gene called ICAM-1 on the surface ofendothelial cells.

Much of Minhajuddin's research on TRF was carried out in India until hejoined the UR faculty in 2003. A Research Fellowship from the IndianCouncil of Agricultural Research, New Delhi, funded his work.

Contact:

Leslie Orrleslie_orr@urmc.rochester.edu585-275-5774University of Rochester Medical Center