title: Effects of tomato- and soy-rich diets on the IGF-I hormonal network: a crossover study of postmenopausal women at high risk for breast cancer.
abstract: To determine whether dietary modifications with tomato products and/or a soy supplement affected circulating levels of insulin-like growth factor (IGF)-1 and other markers of cell signaling in postmenopausal women at risk for developing breast cancer. Eligible and consented postmenopausal women at high risk for developing breast cancer were enrolled in a 26-week, two-arm (tomato and soy, 10 weeks each) longitudinal dietary intervention study in which each woman served as her own control. Changes in biochemical endpoints including IGF-I, IGF-binding protein (IGFBP)-3, estradiol, sex hormone-binding globulin (SHBG), C-peptide, and insulin were measured for each intervention arm. Carotenoid and isoflavone levels were measured to assess adherence. Significant increases in carotenoid and isoflavone levels during the tomato and soy study arms, respectively, suggested that women were adherent to both arms of the intervention. The tomato-rich diet had little effect on cell-signaling biomarkers previously associated with breast cancer risk. However, results of the soy intervention showed that concentrations of IGF-I and IGFBP-3 increased by 21.6 and 154.7 μmol/L, respectively (P = 0.001 for both) and SHBG decreased by 5.4 μmol/L (P < 0.001) after consumption of the soy protein supplement. Increased soy protein intake may lead to small, but significant, increases in IGF-I and IGFBP-3. Soy consumption also led to a significant decrease in SHBG, which has been hypothesized to promote, rather than prevent, cancer growth. Previous epidemiologic studies, however, have confirmed protective effect of soy on breast cancer. Additional investigation about the effect of soy on breast cancer risk and its mechanism of action is warranted.
authors.affiliation: The Ohio State University, Comprehensive Cancer Center, Columbus, OH 43210, USA. mclaugj1@gmail.com
authors.forename: John M
authors.initials: JM
authors.lastname: McLaughlin
authors.forename: Susan
authors.initials: S
authors.lastname: Olivo-Marston
authors.forename: Mara Z
authors.initials: MZ
authors.lastname: Vitolins
authors.forename: Marisa
authors.initials: M
authors.lastname: Bittoni
authors.forename: Katherine W
authors.initials: KW
authors.lastname: Reeves
authors.forename: Cecilia R
authors.initials: CR
authors.lastname: Degraffinreid
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Schwartz
authors.forename: Steven K
authors.initials: SK
authors.lastname: Clinton
authors.forename: Electra D
authors.initials: ED
authors.lastname: Paskett
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000378:metabolism* / Q000517:prevention & control*; D018592:Cross-Over Studies; D004032:Diet; D005260:Female; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000032:analysis; D018969:Insulin-Like Growth Factor Binding Proteins / Q000032:analysis; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D008137:Longitudinal Studies; D018551:Solanum lycopersicum; D008875:Middle Aged; D017698:Postmenopause; D012307:Risk Factors; D030262:Soybean Proteins
chemical_list: D018972:Insulin-Like Growth Factor Binding Protein 3; D018969:Insulin-Like Growth Factor Binding Proteins; D030262:Soybean Proteins; D007334:Insulin-Like Growth Factor I