Scientific Program (Oral Abstracts) | Poster Abstracts | Speaker List
SECOND INTERNATIONAL SYMPOSIUM
ON THE ROLE OF SOY
IN PREVENTING AND TREATING CHRONIC DISEASESeptember 15-18, 1996
Brussells, Belgium
SCIENTIFIC PROGRAM
(Oral Abstracts)Soy and Heart Disease : Hypercholesterolemic Effects of Soy :
Potential MechanismsMechanisms for the Hypocholeste-rolemic Effect of Soy Protein in Normocholesterolemic and Hypercholesterolemic Men
William W. Wong, David L. Hachey, E. O'Brian Smith, Janice E. Stuff, William C. Heird, and Henry J. Pownall*
USDA/ARS Children's Nutrition Research Center, Departments of Pediatrics and Medicine*, Baylor College of Medicine, Houston, Texas 77030.To determine the mechanisms by which soy protein lowers plasma lipid levels in humans, cholesterol absorption and bile acid kinetics were measured in 13 normocholesterolemic and 13 hypercholesterolemic men while consuming a soy protein or animal protein NCEP Step 1 diet. Subjects were randomly assigned to receive either the soy protein or animal protein diet for 36 days, followed by a washout period of regular diet for 70 to 107 days, and then the alternative diet for another 36 days. Fasting blood samples were collected at the beginning of, and at weekly intervals during, each dietary treatment. Metabolic studies were performed on day 28 of each dietary period. On day 1 of each metabolic study, subjects received 250 mg of 18O-cholesterol, 50 mg of 13C-chenodeoxycholic acid (13C-CDCA), and 50 mg of 13C-cholic acid (13C-CA) by mouth and 50 mg of 13C5-cholesterol by vein. Plasma enrichments of 18O-cholesterol, 13C-CDCA, 13C-CA, and 18C5-cholesterol were measured by negative chemical ionization gas chromatography-mass spectrometry. Fractional cholesterol absorption was determined from the 4-day plasma ratio of the orally ingested 18O-cholesterol to the intravenously administered 13C5-cholesterol. Pool sizes and fluxes of CDCA and CA were determined from the plasma terminal decay curves of the orally ingested 13C-CDCA and 13C-CA. Preliminary results indicate that substitution of animal protein in the NCEP Step 1 diet with soy protein lowers the LDL-C levels of both normocholesterolemic and hypercholesterolemic men. Fractional cholesterol absorption and CA kinetics were not different between the two diets. However, the soy protein diet increased the pool size (9.3 for meat vs. 11.4 mg/kg for soy, p = 0.009) and flux (1.4 vs. 1.7 mg/kg/d, p = 0.07) of CDCA. Our data therefore indicate that soy protein enhances the hypocholesterolemic effect of the NCEP Step 1 diet in both normocholesterolemic and hypercholesterolemic men by upregulation of cholesterol excretion via the CDCA pathway.
Soy Symposium Home http://soyfoods.com/symposium/
U.S. Soyfoods Directory Home http:soyfoods.com/
© Copyright 1997
Indiana Soybean Board