Effects of feeding 4 levels of soy protein for 3 and 6 wk on blood lipids and apolipoproteins in moderately hypercholesterolemic men.
BACKGROUND
Replacing animal protein with soy protein has been shown to reduce total and LDL-cholesterol concentrations in humans. However, the minimum amount of soy protein required for significant reduction of blood lipids is not known.


OBJECTIVE
We evaluated the amount of soy protein needed to reduce blood lipids in moderately hypercholesterolemic men.


METHODS
Eighty-one men with moderate hypercholesterolemia (total cholesterol concentration between 5.70 and 7.70 mmol/L) were studied. After a 3-wk lead-in on a Step I diet, total cholesterol was measured and subjects were randomly divided into 5 groups. For 6 wk, each group received 50 g protein/d, which included isolated soy protein (ISP) and casein, respectively, in the following amounts: 50:0, 40:10, 30:20, 20:30, and 0:50 (control group) g. Blood was collected at baseline and weeks 3 and 6 of the intervention.


RESULTS
At week 6, significant reductions (P < 0.05) from baseline compared with the control group were found for non-HDL and total cholesterol and apolipoprotein (apo) B for all ISP groups (except total cholesterol with 40 g ISP). At week 3, significant reductions (P < 0.05) were found in apo B for the groups that consumed >/=30 g ISP and in non-HDL cholesterol for the groups that consumed >/=40 g ISP. HDL-cholesterol, apo A-I, lipoprotein(a), and triacylglycerol concentrations were not significantly affected by dietary treatment.


CONCLUSIONS
Our findings show that consuming as little as 20 g soy protein/d instead of animal protein for 6 wk reduces concentrations of non-HDL cholesterol and apo B by approximately 2.6% and 2.2%, respectively. 2000;71:-84.
Teixeira
S R
SR
Division of Nutritional Sciences, the Department of Veterinary Pathobiology and Community Health, and the Functional Foods for Health Program, University of Illinois at Urbana-Champaign, Urbana, USA.
Potter
S M
SM
Weigel
R
R
Hannum
S
S
Erdman
J W
JW
Hasler
C M
CM
D000328:Adult; D000368:Aged; D016632:Apolipoprotein A-I / Q000097:blood; D001053:Apolipoproteins / Q000097:blood*; D001055:Apolipoproteins B / Q000097:blood; D015992:Body Mass Index; D002784:Cholesterol / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D015331:Cohort Studies; D004305:Dose-Response Relationship, Drug; D006801:Humans; D006937:Hypercholesterolemia / Q000097:blood / Q000178:diet therapy*; D007529:Isoflavones / Q000097:blood; D016014:Linear Models; D008055:Lipids / Q000097:blood*; D017270:Lipoprotein(a) / Q000097:blood; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D030262:Soybean Proteins / Q000378:metabolism*; D014280:Triglycerides / Q000097:blood
D016632:Apolipoprotein A-I; D001053:Apolipoproteins; D001055:Apolipoproteins B; D008076:Cholesterol, HDL; D007529:Isoflavones; D008055:Lipids; D017270:Lipoprotein(a); D030262:Soybean Proteins; D014280:Triglycerides; D002784:Cholesterol