SACRAMENTO, Calif., Feb. 20 -- Plant sterols -- recognized for their cholesterol-lowering power when added to margarines, salad dressings and other fats -- are just as effective in reducing low-density lipoprotein, or "bad" cholesterol levels, when added to orange juice, say researchers at UC Davis School of Medicine and Medical Center.
The results, based on a 10-week study of 72 healthy volunteers with mildly elevated cholesterol levels, are published in the March 8 issue of the American Heart Association's journal Arteriosclerosis, Thrombosis and Vascular Biology (available online at http://www.atvbaha.org/ ).
"Lowering LDL cholesterol is a well-accepted means of reducing the likelihood of heart disease," said Sridevi Devaraj, an assistant professor of pathology and investigator in the Laboratory for Atherosclerosis and Metabolic Research at UC Davis Medical Center who led the sterol study. "Fortifying orange juice with plant sterols is an easy and effective way to boost a diet's LDL-fighting power in individuals with mildly elevated cholesterol levels.
"Fifty percent of Americans have mildly elevated cholesterol levels, defined as having a total cholesterol reading of more than 200 mg/dL. The inclusion of sterols in orange juice offers an important treatment option without increasing saturated fat and at the same time providing vitamin C, flavonoids and other essential nutrients."
The American Heart Association and National Cholesterol Education Program recommend a diet that is low in saturated fat and cholesterol and rich in soluble fiber and plant sterols to help individuals reduce their risk of heart disease. Sterols are present in small quantities in a variety of foods, including fruits, vegetables, nuts, seeds, cereals and legumes. Chemically similar to cholesterol, sterols are thought to lower LDL levels in the body by limiting absorption of cholesterol in the intestine. The UC Davis study is the first to show the cholesterol-reducing effects of plant sterols in a nonfat beverage.
For the study, the UC Davis researchers enrolled healthy volunteers ages 20 to 73 with mildly elevated cholesterol levels. The volunteers were asked to eat their normal diet but to drink a cup of juice along with whatever they had for breakfast and dinner. Half of the group had the sterol-fortified orange juice while the others drank regular orange juice by the same manufacturer. Fasting blood tests were taken before and after the study to determine total cholesterol, total triglyceride, LDL cholesterol, high-density lipoprotein cholesterol and apolipoprotein B levels.
"Volunteers who drank the sterol-fortified orange juice had a 7.2-percent decrease in total cholesterol, 12.4-percent decrease in LDL cholesterol, and 7.8-percent decrease in non-high-density lipoprotein levels compared to baseline and to the group that received the non-sterol orange juice group," she said.
"Orange juice has wide appeal since it is consumed by individuals of all ages, from early childhood to old age. And for individuals who do not want to take a drug for mildly elevated cholesterol, this may provide a healthy and attractive alternative."
Previous studies at other institutions have evaluated plant sterols in yogurt and other low-fat and non-fat foods, with variable results. The UC Davis study may be unique in that it did not place volunteers on a special diet and only asked that they drink the juice with their normal meals.
"The fat in the meals may have helped to emulsify the sterols, but further research will need to be done to determine the meal's relevance," said Ishwarlal Jialal, professor of pathology and internal medicine and director of the Laboratory for Atherosclerosis and Metabolic Research at UC Davis Medical Center. "We also would like to investigate whether sterols can add to the LDL-reducing effects of statin drugs in higher-risk individuals. Sterol-fortified orange juice could potentially enable more patients to meet cholesterol level goals as outlined by the National Cholesterol Education Program."
This study was supported with grants from National Institutes of Health and Minute Maid -- The Coca Cola Company.