Effects of soy and probiotic consumption of coronary heart disease risk factors

The purpose of this dissertation was to evaluate the independent and interactive effects of isoflavone-rich soy protein and probiotic bacteria on plasma lipids in healthy postmenopausal and premenopausal women and men and to evaluate the effects of soy consumption on homocysteine and markers of chronic inflammation in postmenopausal women.;Six weeks of soy protein isolate (26 grams soy protein containing 44 milligrams isoflavones per day) or milk protein isolate with and without probiotic capsules (109 colony-forming-units Lactobacillus acidophilus strain DDS-1 and Bifidobacterium longum strain UABL-14) was investigated in 37 postmenopausal women in a randomized crossover design. Probiotic or placebo capsules were administered to 33 premenopausal women and 22 men for 2 menstrual cycles or 2 months in a parallel design.;In postmenopausal women, soy consumption decreased total cholesterol and LDL-cholesterol, increased HDL-cholesterol, and showed a trend toward decreased triglyceride; these effects were more pronounced in hypercholesterolemic women and not present in normocholesterolemic women. Probiotics did not independently lower lipids nor enhance the effects of soy. Concentrations of homocysteine, C-reactive protein, sE-selectin, sVCAM-1, and sICAM-1 were not different between soy and milk diet treatments. None of these results were affected by equol production status.;Plasma concentrations of total cholesterol, HDL-cholesterol, LDL-cholesterol, and triglyceride were not altered by consumption of probiotic or placebo capsules in premenopausal women and men, and were not different between treatment groups following the intervention.;These results confirm a hypocholesterolemic effect of isoflavone-rich soy on plasma lipids in mildly hypercholesterolemic postmenopausal women independent of equol production status, but do not support an independent or additive effect of Lactobacillus acidophilus strain DDS-1 and Bifidobacterium longum strain UABL-14 on plasma lipids in normocholesterolemic or hypercholesterolemic pre- or postmenopausal women or men. Although this dose of soy exerted an effect on lipids, the results did not substantiate the hypothesized decrease in vascular inflammation and homocysteine.