comparison of the effects of 2 doses of soy protein or casein on serum lipids, serum lipoproteins, and plasma total homocysteine in hypercholesterolemic subjects

• Published in: The American journal of clinical nutrition Vol. 76; no. 1; pp. 78 - 84
• Main Authors: Tonstad, Serena, Smerud, Knut, Høie, Lars
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Clinical Nutrition 01.07.2002; American Society for Clinical Nutrition, Inc
• Subjects: administration & dosage; Adult; Aged; Arteriosclerosis; Arteriosclerosis - prevention & control; beverages; Biological and medical sciences; blood; blood lipids; Body Weight; casein; Caseins; Caseins - administration & dosage; cellulose; Cellulose - administration & dosage; Cholesterol; Cholesterol, LDL; Cholesterol, LDL - blood; cotyledons; diet therapy; Dietary Carbohydrates; Dietary Carbohydrates - administration & dosage; Dietary Fats; Dietary Fats - administration & dosage; Dietary Fiber; Dietary Fiber - administration & dosage; Dietary Proteins; Dietary Proteins - administration & dosage; Disorders of blood lipids. Hyperlipoproteinemia; dose response; Energy Intake; Female; high density lipoprotein cholesterol; homocysteine; Homocysteine - blood; Humans; Hypercholesterolemia; Hypercholesterolemia - blood; Hypercholesterolemia - diet therapy; Lipids; Lipids - blood; Lipoprotein(a); Lipoprotein(a) - blood; Lipoproteins; Lipoproteins - blood; low density lipoprotein cholesterol; Male; Medical sciences; men; Metabolic diseases; Middle Aged; Plasma; prevention & control; Proteins; Soy products; soy protein; Soybean Proteins; Soybean Proteins - administration & dosage; triacylglycerols; women; Human; Animal origin; Metabolic diseases; Cholesterol LDL; Lipids; Hyperlipoproteinemia; Lipoprotein; Feeding; Dose activity relation; Apolipoprotein B; Soy protein; Hypercholesterolemia; Lipemia; Casein; Homocystein; Diet; Plant protein; Dyslipemia; Macronutrient
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/76.1.78

Background: Studies have shown that soy protein reduces some atherogenic lipid and lipoprotein concentrations, although lipoprotein(a) concentrations may be increased. The dose response of soy protein has not been established; neither has its effect on plasma total homocysteine. Objective: Our objective was to evaluate the effect of 2 doses of soy protein on lipid, lipoprotein, and homocysteine concentrations. Design: Four to 24 wk after being instructed to consume a lipid-lowering diet, 130 men and women with LDL-cholesterol concentrations ≥ 4 mmol/L were studied during a parallel group trial in which 4 interventions were assigned randomly. Thirty grams isolated soy protein (ISP) and 10 g cotyledon fiber or 50 g ISP and 16.6 g cotyledon fiber or equivalent doses of casein and cellulose were consumed daily as a beverage for 16 wk. Results: When the 2 groups who consumed ISP were compared with the 2 groups who consumed casein, the differences in the net changes from baseline to week 16 in the concentrations of LDL cholesterol and plasma total homocysteine were −0.26 mmol/L (95% CI: −0.43, −0.09 mmol/L; P = 0.01) and −0.8 μmol/L (−1.4, −0.2 μmol/L; P = 0.005), respectively. The effect of the ISP dose was not significant. There were no significant differences between the 2 ISP and the 2 casein groups in changes in lipoprotein(a), HDL-cholesterol, or triacylglycerol concentrations. Conclusions: Adding 30–50 g soy protein/d to a lipid-lowering diet significantly reduced LDL-cholesterol concentrations without increasing lipoprotein(a) concentrations. Plasma total homocysteine concentrations also decreased, suggesting a novel, possibly antiatherosclerotic effect.