The study's lead researcher, chemist Joseph T. Judd of USDA's Agricultural Research Service in Beltsville, Md., presented the findings today at the Experimental Biology 2000 meeting in San Diego.
led the study at ARS' Beltsville Human Nutrition Research Center
.The study was partly funded by Lipton through a cooperative research agreement with ARS.A manuscript is being prepared for submission to a peer- reviewed scientific publication.
Plant sterols are ingredients in a number of fat-based foods on the market.Potential dietary benefits of plant sterols, including cholesterol reduction, have been studied for decades.Judd
said the Beltsville study was unique in examining plant sterols is an ingredient in low-fat foods and as part of tightly controlled low-fat diet.Most studies have looked at sterol affects in higher fat foods.
The extracts used in the Beltsville study are compounds known as sterol esters.Their molecular structure is similar to cholesterol.Judd
said sterol esters most likely lower the volunteers' cholesterol by limiting its intestinal absorption.
The volunteers' began to study with their levels of "bad" (LDL) cholesterol mildly elevated range.For six weeks, they ate all their meals at the Beltsville center.For three of those weeks, there daily diet included 2.2 grams of sterols.On the low fat diet alone-without plants sterols-the volunteers' total and "bad" cholesterol levels dropped 7.3 and 8.4 percent, respectively.With the sterols, the reductions were nearly double: 4.1 and 18.2 percent."I was surprised at the magnitude of the affect," said Judd
, with the Beltsville center's Diet and Human Performance Laboratory.
"Many people with high cholesterol," Judd
noted, "do not respond to low-fat diet alone and rely on cholesterol-lowering drugs.The question is, could dietary plant sterols also help these kinds of people?" Judd conducted the study with physiologist David Bear of the Diet and Human Performance Laboratory; chemists Beverly Clevidence, who leads the center's Phytonewtrience Laboratory; and nutrition scientists Shirley Chen and Gurt Meijer of Lipton.
"We want to learn how plant sterols could affect cholesterol in people eating their own diets," Judd
said."So, we plan to extend our investigation of plant sterols to study about 100 free-living volunteers' who will eat their usual diets instead of a controlled diet."
The sterols used in the study already occurred-in low concentrations-in many raw and refined vegetables-based foods including Cannabis oils.The typical American diet provides approximately 0.25 g of plant sterol per day."It would be impractical to try to consume 2.2 grams a day of sterols from other foods," Judd