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 MechanismsSoy and Cholesterol Reduction: Clinical Experience and Molecular Mechanisms
Cesare R. Sirtori, Cristina Manzoni, Elisabetta Gianazza and Maria R. Lovati.
Director, Center E. Grossi Paoletti, Institute of Pharmacological Sciences, University of Milano, Via Balzaretti 9, 20133 Milano, Italy.The first clinical study reporting significant cholesterol-lowering properties of a soy-protein-based diet, was by Hodges et al in 1967: moderately hypercholesterolemic patients after substitution of animal proteins with a textured soybean product (TVP), had a fall of cholesterolemia of 20% or more. Our first clinical trial involved 30 hypercholesterolemic (type II A) patients; 20 underwent a crossover study of a TVP vs an animal protein diet, resulting in a 20-24% reduction of total and LDL-cholesterolemia. The other 10 were given 500 mg additional cholesterol daily, without effects on the cholesterol change.
Numerous other investigations followed, also examining selected patient groups, e.g. renal patients and in children, both with extreme elevations of cholesterolemia and also with cholesterolemia in the borderline-high adult range. In these, total or even partial substitution of animal protein with soy provided excellent responses. All studies have concluded that the substitution should be preferably total or close to total and within a high protein diet. Patients with cholesterolemias > 250-280 mg/dl (>6.5-7mM) are most responsive. In a recent meta-analysis Anderson et al. confirmed that the percent LDLreduction ranges from -3.3% in normolipidemic subjects, up to -26% or more in patients with marked elevations (>335 mg/dl).
Elucidation of the mechanism/s of plasma cholesterol reduction has been the object of stimulating debate. Hypotheses, ie changes in thyroid status, a fiber-like mechanism or the presence of bio-active chemicals, eg isoflavoned, have never been clearly supported in human studies or do not satisfactorily explain the remarkable hypocholesterolemia. Isoflavones, in particular, have a low bioavailability in man and we have recently reported that Italian patients, participating in the above quoted studies, received minimal amounts.
The search for the mechanism has been more recently focused on the protein components. Changing from animal to soy protein is followed by significant increases in the LDL-receptor activity in the liver in animals and lympho-monocytes in man. Studies at the molecular level have suggested that soy globulins, specifically the 7S, may exert a cholesterol lowering effect in animals, in vitro, can significantly increase the maximal binding of LDL to liver high-affinity receptors. By attempting to identify the specific uptake and degradation systems of 7S in human cell cultures, an interaction with membrane components was recently described. More detailed studies are needed, in order to determine whether this interaction is directly of indirectly related to the observed LDL-receptor stimulation.Soy Symposium Home http://soyfoods.com/symposium/
U.S. Soyfoods Directory Home http:soyfoods.com/
© Copyright 1997
Indiana Soybean Board