Background: Clinical trials have suggested that the intake of soy protein reduces blood cholesterol. Few studies have explored this relation in subjects who consume soy as part of their regular diet.
Objective: In this study, we investigated whether blood cholesterol concentrations are related to the intake of soyfoods in a cohort comprising subjects with a wide variation in soy intake.
Design: This cross-sectional study included 1033 pre- and postmenopausal women selected from the Oxford arm of the European Prospective Investigation into Cancer and Nutrition. The sample included 361 nonvegetarians, 570 vegetarians, and 102 vegans. Their dietary intake was assessed by using a food-frequency questionnaire. Anthropometric data, medical history, and lifestyle information were obtained with the use of a questionnaire, blood samples were obtained, and plasma total, LDL-, and HDL-cholesterol concentrations were measured.
Results: Soy-protein intake was inversely associated with total and LDL-cholesterol concentrations and with the ratio of total to HDL cholesterol but not with HDL-cholesterol concentrations. Mean plasma LDL-cholesterol concentrations in women with a soy-protein intake >/=6 g/d was 12.4% lower than that in women who consumed <0.5 g/d (P < 0.001).
Conclusion: Moderate intakes of soyfoods as part of a regular diet are associated with favorable blood cholesterol concentrations.