Serum IGF-1 Concentrations Change With Soy and Seaweed Supplements in Healthy Postmenopausal American Women

• Published in: Nutrition and cancer 2011-07, Vol.63 (5), p.743-748
• Main Authors: Teas, Jane, Irhimeh, Mohammad R, Druker, Susan, Hurley, Thomas G, Hebert, James R, Savarese, Todd M, Kurzer, Mindy S
• Format: Article
• Language: English
• Subjects: adults; Aged; Alaria; Alaria esculenta; Algae; Biological and medical sciences; Biomarkers - blood; blood serum; body weight; Breast cancer; breast neoplasms; Breast Neoplasms - epidemiology; Breast Neoplasms - prevention & control; Capsules; clinical trials; Cross-Over Studies; Dietary supplements; Dietary Supplements - adverse effects; Double-Blind Method; fasting; Feeding. Feeding behavior; Female; foods; Fundamental and applied biological sciences. Psychology; Glycine max - chemistry; Humans; Insulin-Like Growth Factor Binding Protein 3 - blood; insulin-like growth factor I; Insulin-Like Growth Factor I - analysis; Insulin-like growth factors; isoflavones; macroalgae; Massachusetts - epidemiology; Menopause; Middle Aged; nutritional status; Phaeophyceae - chemistry; postmenopause; Postmenopause - blood; protein isolates; Risk; Seaweed - chemistry; Seeds - chemistry; Vertebrates: anatomy and physiology, studies on body, several organs or systems; women; Womens health
• ISSN: 0163-5581; 1532-7914; 1532-7914
• DOI: 10.1080/01635581.2011.579383

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.