title: A comparison of the effects of 2 doses of soy protein or casein on serum lipids, serum lipoproteins, and plasma total homocysteine in hypercholesterolemic subjects.
abstract: 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.
  
  
  METHODS
  Four to 24 wk after being instructed to consume a lipid-lowering diet, 130 men and women with LDL-cholesterol concentrations > or = 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 micromol/L (-1.4, -0.2 micromol/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.
authors.affiliation: Department of Preventive Cardiology, Ullevål Hospital, Oslo , Norway. serena.tonstad@ulleval.no
authors.forename: Serena
authors.initials: S
authors.lastname: Tonstad
authors.forename: Knut
authors.initials: K
authors.lastname: Smerud
authors.forename: Lars
authors.initials: L
authors.lastname: Høie
mesh_terms: D000328:Adult; D000368:Aged; D001161:Arteriosclerosis / Q000517:prevention & control; D001835:Body Weight; D002364:Caseins / Q000008:administration & dosage*; D002482:Cellulose / Q000008:administration & dosage; D008078:Cholesterol, LDL / Q000097:blood; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D004043:Dietary Fiber / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D002149:Energy Intake; D005260:Female; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D006937:Hypercholesterolemia / Q000097:blood / Q000178:diet therapy*; D008055:Lipids / Q000097:blood*; D017270:Lipoprotein(a) / Q000097:blood; D008074:Lipoproteins / Q000097:blood*; D008297:Male; D008875:Middle Aged; D030262:Soybean Proteins / Q000008:administration & dosage*
chemical_list: D002364:Caseins; D008078:Cholesterol, LDL; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004043:Dietary Fiber; D004044:Dietary Proteins; D008055:Lipids; D017270:Lipoprotein(a); D008074:Lipoproteins; D030262:Soybean Proteins; D006710:Homocysteine; D002482:Cellulose