Effect of soy protein-containing isoflavones on lipoproteins in postmenopausal women.
OBJECTIVE
Some clinical trials have demonstrated a beneficial effect of dietary soy protein on improving lipoproteins. Research also has documented that serum lipoproteins and some lipoprotein subclasses are altered as a consequence of menopause, resulting in a more atherogenic lipid profile. The purpose of this study was to determine the effects of isolated soy protein-containing isoflavones on lipoproteins and lipoprotein subclasses in both African American and white postmenopausal women with borderline to moderate low-density lipoprotein cholesterol elevations.


METHODS
This was a randomized, double-blind, controlled clinical trial including 216 postmenopausal women. After a 4-week run-in period with a casein protein-based supplement, participants were randomly assigned to continue the casein placebo or receive soy protein-containing isoflavones for a period of 12 weeks.


RESULTS
In the soy group, the total cholesterol, low-density lipoprotein cholesterol, and low-density lipoprotein particle number decreased significantly as compared with the placebo group at 6 weeks. Although this decrease continued at 12 weeks in the soy group, the difference from the placebo group was attenuated for total cholesterol and low-density lipoprotein particle number. Multivariate analyses controlling for age, race, change in weight, change in dietary fat intake, and change in kilocalorie energy expenditure revealed that treatment remained a significant independent predictor of change in total cholesterol (P = 0.01), low-density lipoprotein cholesterol (P = 0.02), and low-density lipoprotein particle number (P = 0.002) after 6 weeks of dietary soy.


CONCLUSIONS
Increased consumption of soy protein replacing animal protein that is high in fat may help improve atherogenic lipid profiles.
Allen
Jerilyn K
JK
Johns Hopkins University School of Nursing, Baltimore, MD 21205, USA. jallen@son.jhmi.edu
Becker
Diane M
DM
Kwiterovich
Peter O
PO
Lindenstruth
Kathleen A
KA
Curtis
Carol
C
D002364:Caseins / Q000494:pharmacology*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007529:Isoflavones / Q000494:pharmacology*; D008074:Lipoproteins / Q000097:blood*; D008875:Middle Aged; D015999:Multivariate Analysis; D017698:Postmenopause / Q000097:blood / Q000187:drug effects*; D030262:Soybean Proteins / Q000494:pharmacology*
D002364:Caseins; D007529:Isoflavones; D008074:Lipoproteins; D030262:Soybean Proteins