Effect of soy protein-containing isoflavones on lipoproteins in postmenopausal women.

OBJECTIVE: Some clinical trials have demonstrated a beneficial effect of dietary soy protein on improving lipoproteins. Research also has documented that serum lipoproteins and some lipoprotein subclasses are altered as a consequence of menopause, resulting in a more atherogenic lipid profile. The purpose of this study was to determine the effects of isolated soy protein-containing isoflavones on lipoproteins and lipoprotein subclasses in both African American and white postmenopausal women with borderline to moderate low-density lipoprotein cholesterol elevations. DESIGN: This was a randomized, double-blind, controlled clinical trial including 216 postmenopausal women. After a 4-week run-in period with a casein protein-based supplement, participants were randomly assigned to continue the casein placebo or receive soy protein-containing isoflavones for a period of 12 weeks. RESULTS: In the soy group, the total cholesterol, low-density lipoprotein cholesterol, and low-density lipoprotein particle number decreased significantly as compared with the placebo group at 6 weeks. Although this decrease continued at 12 weeks in the soy group, the difference from the placebo group was attenuated for total cholesterol and low-density lipoprotein particle number. Multivariate analyses controlling for age, race, change in weight, change in dietary fat intake, and change in kilocalorie energy expenditure revealed that treatment remained a significant independent predictor of change in total cholesterol (P = 0.01), low-density lipoprotein cholesterol (P = 0.02), and low-density lipoprotein particle number (P = 0.002) after 6 weeks of dietary soy. CONCLUSIONS: Increased consumption of soy protein replacing animal protein that is high in fat may help improve atherogenic lipid profiles.

Recruitment of African American and white postmenopausal women into clinical trials: the beneficial effects of soy trial experience.

OBJECTIVE: To describe the strategies and costs associated with recruiting both African American and White postmenopausal women into a randomized controlled trial. DESIGN: The Beneficial Effects of Soy Trial (BEST) was a randomized, controlled trial designed to determine the effects of a dietary soy supplement on lipoproteins, lipoprotein subclasses, and menopausal symptoms in African American and White postmenopausal women. The goal was to have > or = 80 African American and > or = 80 White women complete the study. RESULTS: A total of 705 postmenopausal women (381 African American, 324 White) were screened, and of those, 217 were randomized (105 African American, 112 White), and 192 (91 African American, 101 White) completed the study. Direct mailings to targeted zip codes proved the most successful recruitment strategy for recruiting African Americans (52% of African Americans recruited) and the second most effective for recruiting Whites (32% of Whites recruited). Newspaper advertisements yielded the highest number of White participants (36%) but proved less successful for recruiting African Americans (8%). Airing advertisements on the radio was the second most effective strategy for recruiting African Americans (15%), yet it was one of the least effective approaches for recruiting Whites (5%). The total cost of recruitment was dollar 49,036.25, which averaged dollar 255.40 per participant who completed the study. The three most successful strategies, direct mailings, newspaper ads, and radio ads, were the three most expensive approaches but yielded 73% of all participants who completed the study.