Effect of soy protein varying in isoflavone content on serum lipids in healthy young men.
BACKGROUND
Previous research supports a role for soy protein in reducing serum lipids; however, few studies involved healthy male subjects or focused on soy isoflavones (or did both).


OBJECTIVE
The objective was to ascertain the effects of soy protein varying in isoflavone content on serum lipids in healthy young men.


METHODS
Thirty-five males (x +/- SD age: 27.9 +/- 5.7 y) consumed milk protein isolate (MPI), low-isoflavone soy protein isolate (low-iso SPI; 1.64 +/- 0.19 mg aglycone isoflavones/d), and high-isoflavone SPI (high-iso SPI; 61.7 +/- 7.4 mg aglycone isoflavones/d) for 57 d each, separated by 4-wk washout periods, in a randomized crossover design. Blood samples were collected at the beginning and end of each treatment period, and total, LDL, and HDL cholesterol; triacylglycerols; apolipoprotein (apo) B; apo A-I; and C-reactive protein (CRP) were measured in serum. Twenty-four-hour urine samples were collected for 3 consecutive days at the end of each treatment period and analyzed for isoflavones.


RESULTS
Urinary isoflavones were significantly greater with consumption of the high-iso SPI than with that of the low-iso SPI or MPI. The differences between the 3 treatments with respect to individual serum lipids were not significant, but the ratios of total to HDL cholesterol, LDL to HDL cholesterol, and apo B to apo A-I were significantly lower with both SPI treatments than with MPI treatment.


CONCLUSIONS
Soy protein, regardless of isoflavone content, modulates serum lipid ratios in a direction beneficial for cardiovascular disease risk in healthy young men.
McVeigh
Brianne L
BL
Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Canada.
Dillingham
Barbara L
BL
Lampe
Johanna W
JW
Duncan
Alison M
AM
D000328:Adult; D016632:Apolipoprotein A-I / Q000097:blood; D001055:Apolipoproteins B / Q000097:blood; D002097:C-Reactive Protein / Q000378:metabolism; D002318:Cardiovascular Diseases / Q000097:blood / Q000517:prevention & control*; D002784:Cholesterol / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007529:Isoflavones / Q000008:administration & dosage* / Q000097:blood / Q000652:urine; D008055:Lipids / Q000097:blood* / Q000737:chemistry; D008297:Male; D012307:Risk Factors; D030262:Soybean Proteins / Q000008:administration & dosage* / Q000737:chemistry*; D014280:Triglycerides / Q000097:blood
D016632:Apolipoprotein A-I; D001055:Apolipoproteins B; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D007529:Isoflavones; D008055:Lipids; D030262:Soybean Proteins; D014280:Triglycerides; D002097:C-Reactive Protein; D002784:Cholesterol