title: Serum IGF-1 concentrations change with soy and seaweed supplements in healthy postmenopausal American women.
abstract: Insulin-like growth factor 1 (IGF-1) is an anabolic hormone important for growth and development. However, high-circulating serum concentrations in adults are associated with increased risk of postmenopausal breast cancer. Nutritional status and specific foods influence serum IGF-1 concentrations. Breast cancer incidence is typically low in Asian countries where soy is commonly consumed. Paradoxically, soy supplement trials in American women have reported significant increases in IGF-1. Seaweed also is consumed regularly in Asian countries where breast cancer risk is low. We investigated the possibility that seaweed could modify soy-associated increases in IGF-1 in American women. Thirty healthy postmenopausal women (mean age 58 yr) participated in this 14-wk double-blinded, randomized, placebo-controlled crossover clinical trial. Participants consumed 5 g/day placebo or seaweed (Alaria esculenta) in capsules for 7 wk. During the 7th wk, a high-soy protein isolate powder was added (2 mg/kg body weight aglycone equivalent isoflavones). Overnight fasting blood samples were collected after each intervention period. Soy significantly increased serum IGF-1 concentrations compared to the placebo (21.2 nmol/L for soy vs. 16.9 nmol/L for placebo; P = 0.0001). The combination of seaweed and soy significantly reduced this increase by about 40% (21.2 nmol/L for soy alone vs. 19.4 nmol/L; P = 0.01). Concurrent seaweed and soy consumption may be important in modifying the effect of soy on IGF-1 serum concentrations.
authors.affiliation: Cancer Research Center of the University of South Carolina, Columbia, South Carolina 29208, USA. teas@mailbox.sc.edu
authors.forename: Jane
authors.initials: J
authors.lastname: Teas
authors.forename: Mohammad R
authors.initials: MR
authors.lastname: Irhimeh
authors.forename: Susan
authors.initials: S
authors.lastname: Druker
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Hurley
authors.forename: James R
authors.initials: JR
authors.lastname: Hébert
authors.forename: Todd M
authors.initials: TM
authors.lastname: Savarese
authors.forename: Mindy S
authors.initials: MS
authors.lastname: Kurzer
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D001943:Breast Neoplasms / Q000453:epidemiology / Q000517:prevention & control; D002214:Capsules; D018592:Cross-Over Studies; D019587:Dietary Supplements / Q000009:adverse effects; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D008404:Massachusetts / Q000453:epidemiology; D008875:Middle Aged; D000459:Phaeophyceae / Q000737:chemistry*; D017698:Postmenopause / Q000097:blood*; D012306:Risk; D012624:Seaweed / Q000737:chemistry*; D012639:Seeds / Q000737:chemistry; D013025:Glycine max / Q000737:chemistry*
chemical_list: D015415:Biomarkers; D002214:Capsules; C515497:IGFBP3 protein, human; D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I