Endocrine Abstracts

AIMS: Postmenopausal oestrogen replacement therapy (ERT) has been shown to lower serum insulin-like growth factor 1 (IGF-1) levels, requiring the use of higher doses of growth hormone (GH) replacement. Soy derived phytoestrogens (PE) are in widespread usage as a natural alternative to ERT. No data exists on the effects of PE on serum IGF-1 levels. The aim of this pilot study was to determine the effects of Phytoestrogen dietary supplementation on the serum IGF-1 level in postmenopausal women. METHODS & PATIENTS: Ten postmenopausal women, ages 47-75 years, completed a randomised, double blind, placebo controlled, crossover trial of soy derived PE, 132mg/day, vs. placebo for 12 weeks, separated by a 2 week washout period. No subject was using any form of ERT or was on any medication known to alter the GH/IGF-1 axis. The subjects were weighed and fasting blood was collected and at baseline and after both phases for analysis of IGF-1 and Lipid profile. Mean results obtained after the two treatment phases were compared using the paired t test for data that had a Gaussian distribution and by the Wilcoxon signed ranks test when not of Gaussian distribution. RESULTS: When compared with placebo, Phytoestrogen supplementation significantly reduced total cholesterol (5.7 plus/minus 1.1 vs 6.1 plus/minus 1.1 mmol/L, p=0.043) and low density lipoprotein cholesterol (3.4 plus/minus 0.8 vs 3.9 plus/minus 1.0 mmol/L, p=0.008), but produced no significant change in IGF-1 (72.6 plus/minus 26.7 vs 69.9 plus/minus 24.2, p=0.398), triglycerides (2.4 plus/minus 1.5 vs 2.4 plus/minus 1.3 mmol/L, p=0.867), high density lipoprotein cholesterol (1.2 plus/minus 0.3 vs 1.2 plus/minus 0.3 mmol/L, p=0.496) and weight (80.9 plus/minus 9.5 vs 80.6 plus/minus 8.9 kg, p=0.574). CONCLUSION: We conclude that in contrast to ERT, dietary supplementation with phytoestrogens does not adversely affect IGF-1 levels whilst producing similar beneficial effects on the lipid profile.