Long term effects of soy protein and isoflavones on plasma lipid profiles in postmenopausal women

The effects of 40 g/d of soybean protein containing moderate and high levels of isoflavones on lipoproteins and other selected cardiovascular risk factors were investigated in 75 hypercholesterolemic free-living postmenopausal females (49 to 83 yrs of age) during a six month parallel group double-blind trial with three intervention arms. After a control period of 14 days, during which subjects followed an NCEP Step I low fat (30% of kcal) and low cholesterol (<300mg/d) dietary regimen, all subjects were randomly assigned to one of three dietary groups: NCEP Step I diet with 40 g protein obtained from casein/NFDM (non-fat dry milk), NCEP Step I diet with 40 g protein from isolated soy protein containing 0.8 mg isoflavones/g protein or NCEP Step I diet with 40 g protein from isolated soy protein ' containing 1.6 mg isoflavones/g protein. Blood samples were collected at baseline and every 6 weeks for the duration of the study and plasma concentrations of total, HDL, HDL2, HDL, LDL, VLDL cholesterol, total triglycérides, and apoprotein A-I and B were analyzed at baseline and at the end of each period. Results will be presented. (Funded by the Illinois Soybean Operating Board).