Effects of high- and low-isoflavone soyfoods on blood lipids, oxidized LDL, homocysteine, and blood pressure in hyperlipidemic men and women.
BACKGROUND
Many of the benefits of soy have been attributed to soy isoflavones.


OBJECTIVE
The objective was to determine the effects of high- and low-isoflavone soy-protein foods on both lipid and nonlipid risk factors for coronary artery disease (CAD).


METHODS
Forty-one hyperlipidemic men and postmenopausal women participated in a study with three 1-mo diets: a low-fat dairy food control diet and high- (50 g soy protein and 73 mg isoflavones daily) and low- (52 g soy protein and 10 mg isoflavones daily) isoflavone soyfood diets. All 3 diets were very low in saturated fat (< 5% of energy) and cholesterol (< 50 mg/d). Fasting blood samples were drawn and blood pressure was measured at the start and end of each diet.


RESULTS
No significant differences were seen between the high- and low-isoflavone soy diets. Compared with the control diet, however, both soy diets resulted in significantly lower total cholesterol, estimated CAD risk, and ratios of total to HDL cholesterol, LDL to HDL cholesterol, and apolipoprotein B to A-I. No significant sex differences were observed, except for systolic blood pressure, which in men was significantly lower after the soy diets than after the control diet. On the basis of blood lipid and blood pressure changes, the calculated CAD risk was significantly lower with the soy diets, by 10.1 +/- 2.7%.


CONCLUSIONS
Substitution of soyfoods for animal products, regardless of isoflavone concentration, reduces the CAD risk because of both modest reductions in blood lipids and reductions in oxidized LDL, homocysteine, and blood pressure.
Jenkins
David J A
DJ
Clinical Nutrition and Risk Factor Modification Center, St Michael's Hospital, Toronto, Ontario, Canada. cyril.kendall@utoronto.ca
Kendall
Cyril W C
CW
Jackson
Chung-Ja C
CJ
Connelly
Philip W
PW
Parker
Tina
T
Faulkner
Dorothea
D
Vidgen
Edward
E
Cunnane
Stephen C
SC
Leiter
Lawrence A
LA
Josse
Robert G
RG
D001794:Blood Pressure / Q000187:drug effects*; D002784:Cholesterol / Q000097:blood; D003327:Coronary Disease / Q000517:prevention & control*; D018592:Cross-Over Studies; D004044:Dietary Proteins / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D006949:Hyperlipidemias / Q000188:drug therapy*; D007529:Isoflavones / Q000008:administration & dosage / Q000627:therapeutic use*; D008055:Lipids / Q000097:blood*; D008297:Male; D008875:Middle Aged; D017698:Postmenopause; D030262:Soybean Proteins / Q000008:administration & dosage / Q000627:therapeutic use*
D004044:Dietary Proteins; D007529:Isoflavones; D008055:Lipids; D030262:Soybean Proteins; D006710:Homocysteine; D002784:Cholesterol