title: Effects of high- and low-isoflavone (phytoestrogen) soy foods on inflammatory biomarkers and proinflammatory cytokines in middle-aged men and women.
abstract: This study sought to determine effects of high- and low-isoflavone soy protein foods on acute-phase proteins and proinflammatory cytokines and whether isoflavone phytoestrogens might act as estrogens, which enhance the immune response. Forty-one hypercholesterolemic men and postmenopausal women underwent three 1-month diets consisting of a low-fat dairy food control phase and high- and low-isoflavone soy food test phases (50 g/d and 52g/d soy protein, respectively, and 73 mg/d and 10 mg/d isoflavone, respectively). Diets were low in saturated fat (<5% of energy) and cholesterol (<50 mg/d). Fasting blood analytes and blood pressure were measured at the start and end of each phase. For the entire group of subjects, no treatment differences were observed for acute-phase proteins or proinflammatory cytokines. However, a significant interaction was noted between diet and sex. Assessing the results of men and women separately, women showed significantly higher interleukin-6 (IL-6) values after the high-isoflavone soy diet (P =.013) compared to control values. For women, the difference between the high- and low-isoflavone IL-6 values was significant using the unadjusted data (P =.048) but not after adjustment. No significant effects were seen for men or women in C-reactive protein (CRP), serum amyloid A (SAA), or tumor necrosis factor-alpha (TNF-alpha). Thus, high levels of isoflavone intake appear to increase serum concentrations of IL-6 in women. This finding may indicate an estrogenic effect of soy isoflavones in enhancing the immune response and provide a possible explanation through enhanced immune surveillance for lower incidence of certain cancers in soy-eating parts of the world.
authors.affiliation: Clinical Nutrition and Risk Factor Modification Center, and the Department of Medicine, Division of Endocrinology and Metabolism, St Michael's Hospital, Toronto, Ontario, Canada.
authors.forename: David J A
authors.initials: DJ
authors.lastname: Jenkins
authors.forename: Cyril W C
authors.initials: CW
authors.lastname: Kendall
authors.forename: Philip W
authors.initials: PW
authors.lastname: Connelly
authors.forename: Chung-Ja C
authors.initials: CJ
authors.lastname: Jackson
authors.forename: Tina
authors.initials: T
authors.lastname: Parker
authors.forename: Dorothea
authors.initials: D
authors.lastname: Faulkner
authors.forename: Edward
authors.initials: E
authors.lastname: Vidgen
mesh_terms: D000284:Administration, Oral; D001053:Apolipoproteins / Q000097:blood; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000032:analysis; D002791:Cholesterol, Dietary / Q000494:pharmacology; D016207:Cytokines / Q000097:blood*; D004032:Diet; D004041:Dietary Fats / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004968:Estrogens, Non-Steroidal / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D006937:Hypercholesterolemia / Q000097:blood / Q000178:diet therapy*; D007249:Inflammation / Q000097:blood / Q000178:diet therapy*; D015850:Interleukin-6 / Q000097:blood; D007529:Isoflavones / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D048789:Phytoestrogens; D028321:Plant Preparations; D000685:Serum Amyloid A Protein; D012737:Sex Factors; D013025:Glycine max; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis
chemical_list: D001053:Apolipoproteins; D015415:Biomarkers; D002791:Cholesterol, Dietary; D016207:Cytokines; D004041:Dietary Fats; D004968:Estrogens, Non-Steroidal; D015850:Interleukin-6; D007529:Isoflavones; D048789:Phytoestrogens; D028321:Plant Preparations; D000685:Serum Amyloid A Protein; D014409:Tumor Necrosis Factor-alpha; D002097:C-Reactive Protein