Effects of soy bean on serum paraoxonase 1 activity and lipoproteins in hyperlipidemic postmenopausal women.
OBJECTIVE
Because of an unfavorable serum lipoprotein profile, postmenopausal women are at risk of cardiovascular disease. Soy protein may help protect against these risk factors, although its effect on paraoxonase 1 (PON1) is not clear. The aim of the present study was to determine the effects of soy protein on serum concentration of lipoproteins and PON1 activity in hypercholesterolemic postmenopausal women.


METHODS
In a double-blind randomized clinical trial with a parallel design, 52 hypercholesterolemic postmenopausal women were randomly assigned to 50 g/day soy protein containing 164 mg isoflavones or placebo, for 10 weeks. Serum lipoproteins and PON1 activity were measured at baseline and at the 10th week.


RESULTS
There was significant increase in PON1 activity (P=0.029) and a significant decrease in low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), LDL-C/high-density lipoprotein cholesterol (HDL-C), triacylglycerol/HDL-C and TC/HDL-C in the soy group compared with the placebo group (P=0.001, P=0.008, P=0.012, P=0.04 and P=0.029, respectively) at the end of the study. Similarly, PON1 activity was significantly increased (P=0.015) and LDL-C, TC, LDL-C/HDL-C, triacylglycerol/HDL-C and TC/HDL-C were significantly decreased (P=0.001, P=0.002, P=0.001, P=0.016 and P=0.001) at the end of the study compared with the beginning value in soy group.


CONCLUSIONS
Soy protein reduces the cardiovascular disease risk in postmenopausal women because of both modest reductions in serum lipoproteins and an increase in PON1 activity.
Shidfar
Farzad
F
School of Health, Iran University of Medical Sciences, Tehran, Iran. farzadshidfar@yahoo.com
Ehramphosh
Elham
E
Heydari
Iraj
I
Haghighi
Ladan
L
Hosseini
Sharieh
S
Shidfar
Shahrzad
S
D043303:Aryldialkylphosphatase / Q000097:blood*; D002318:Cardiovascular Diseases / Q000097:blood / Q000517:prevention & control; D008076:Cholesterol, HDL / Q000097:blood; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006937:Hypercholesterolemia / Q000188:drug therapy*; D007492:Iran; D008074:Lipoproteins / Q000097:blood* / Q000187:drug effects; D008875:Middle Aged; D017698:Postmenopause / Q000097:blood*; D012307:Risk Factors; D030262:Soybean Proteins / Q000494:pharmacology*; D013997:Time Factors
D008076:Cholesterol, HDL; D008074:Lipoproteins; D030262:Soybean Proteins; D043303:Aryldialkylphosphatase; C468406:PON1 protein, human