Soy stanols and cholesterol absorption - Positive Effects of Foods

Nutrition Research Newsletter, June, 2003

There is a growing consensus that reduction of LDL (low-density lipoprotein) cholesterol is a critical component of both prevention and treatment of coronary heart disease. Phytosterols and phytostanols, which are found in unrefined vegetable foods, lower LDL cholesterol and have a favorable safety profile, making them candidates for use in dietary treatment.

Despite these promising attributes, the practical use of phytostanols has been limited by their low water solubility and a very slow rate of dissolution in physiological bile salt solutions. An alternative approach used is the emulsification of phytostanols with small amounts of lecithin. Lecithin disperses easily in water and forms water-soluble micelles that can include stanols. Therefore, a recent study tired to prove that fat-free, lecithin-formulated soy stanols lower cholesterol absorption and serum LDL cholesterol.

Forty-five subjects were enrolled in three studies: 21 subjects for two cholesterol absorption studies using single test meals and 24 subjects for a 10-week study of LDL lowering. Reduction in cholesterol absorption was measured using egg whites that contained 625 mg stanols and a cholesterol tracer. In the LDL reduction study, the subjects received a lemonade beverage three times a day for a 10-week period. The primary endpoint was change in LDL and total cholesterol. During a 6-week, dietary run-in period, the subjects received a placebo with each meal and followed the American Heart Association step 1 diet. After this lead-in period, a 4-week randomized period began with consumption of either active (625 mg stanols and 550 mg lecithin) or placebo (550 mg lecithin) beverage three times a day. Lipoproteins were measured after a week as well as after four weeks of treatment. Patients fasted for at least 12 hours and then total cholesterol, triacylglycerols, and HDL cholesterol were measured. Low-density lipoprotein cholesterol was calculated using the Friedewald formula.

Stanol-lecithin reduced cholesterol absorption by 32.1% and by 38.2% when delivered in a lemonade-flavored beverage and in egg whites, respectively. Reduction in cholesterol absorption was strongly related to the initial level of absorbed cholesterol tracer in serum. During the treatment period, all subjects who received stanols-lecithin had reduced LDL cholesterol and total cholesterol. The difference between treatment groups was a 14.3% reduction in LDL cholesterol and a 10.1% reduction in total cholesterol. There were no significant changes in HDL cholesterol or triacylglycerols. Stanols lowered the ratio of LDL cholesterol to HDL cholesterol by 13%.

Soy stanols-lecithin powder can be reconstituted in lemonade to produce a clinically active drink that lowers cholesterol absorption in single test meals and reduces LDL and total cholesterol during chronic treatment. The degree of LDL lowering observed with a dose of 1.9 g stanols per day was 14.3% relative to controls, which compares favorably with values observed previously with stanol margarines. Incorporation of lecithin-emulsified soy sterols into nonfat food products has the potential to provide the dietitian with another avenue for the nonpharmaceutical treatment of hyperlipidemia. The ability to deliver these compounds in water provides a flexible system that is amenable to many different food or beverage types. These results show that solubilization of phytosterols in dietary fat is not necessarily a prescription for more dietary fat.

Curtis A. Spilburg, Anne C. Goldberg, Janet B. McGill, et al. Fat-Free Foods Supplemented with Soy Stanol-Lecithin Powder Reduce Cholesterol Absorption and LDL Cholesterol, JADA (103[5]: 577-581, May 2003). Address correspondence to: Curtis A. Spilburg, PhD, President, Lifeline Technologies, 400 Chesterfield Center, Suite 120, Chesterfield, MO 63017. E-mail: Spilburg@aol.com