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Green Tea Catechin Extract Supplementation Does Not Influence Circulating Sex Hormones and Insulin-Like Growth Factor Axis Proteins in a Randomized Controlled Trial of Postmenopausal Women at High Risk of Breast Cancer.
- Source :
-
Journal of Nutrition . Apr2019, Vol. 149 Issue 4, p619-627. 9p. - Publication Year :
- 2019
-
Abstract
- <bold>Background: </bold>Consumption of green tea has been associated with reduced risk of breast cancer. Hormonal modulation has been suggested as one of the potential underlying mechanisms; however, it has yet to be fully elucidated in large, long-term human clinical trials.<bold>Objective: </bold>We investigated the effects of decaffeinated green tea extract (GTE) on circulating sex hormones and insulin-like growth factor (IGF) proteins.<bold>Methods: </bold>We conducted a placebo-controlled double-blind randomized clinical trial recruiting from 8 clinical centers in Minnesota. Participants were 538 healthy postmenopausal women randomly assigned to the GTE group (463 completed the study; mean age = 60.0 y) and 537 to the placebo group (474 completed; mean age = 59.7 y). Women in the GTE group orally took 4 decaffeinated capsules containing 1315 mg total catechins including 843 mg epigallocatechin-3-gallate daily for 1 y, whereas women in the placebo group took similar capsules containing no tea catechins. Blood sex hormones (estrone, estradiol, androstenedione, testosterone, and sex hormone-binding globulin) and IGF proteins (IGF-1 and IGF binding protein-3) were quantified at baseline and months 6 (for IGF proteins only) and 12, and were assessed as secondary outcomes of the study using a mixed-effect repeated-measures ANOVA model.<bold>Results: </bold>Women in the GTE group had significantly higher blood total estradiol (16%; P = 0.02) and bioavailable estradiol (21%; P = 0.03) than in the placebo group at month 12. There was a statistically significant interaction between GTE supplementation and duration of treatment on estradiol and bioavailable estradiol (both Ps for interaction = 0.001). The catechol-O-methyltransferase genotype did not influence blood sex hormones before or after GTE supplementation. The circulating concentrations of IGF proteins were comparable between GTE and placebo groups at all 3 time points.<bold>Conclusion: </bold>These results suggest that a 12-mo GTE supplementation significantly increases circulating estradiol concentrations in healthy postmenopausal women. This trial was registered at clinicaltrials.gov as NCT00917735. [ABSTRACT FROM AUTHOR]
- Subjects :
- *GREEN tea
*CATECHIN
*SEX hormones
*SOMATOMEDIN
*POSTMENOPAUSE
*BREAST cancer
*RESEARCH
*FLAVONOIDS
*RESEARCH methodology
*EVALUATION research
*MEDICAL cooperation
*DIETARY supplements
*COMPARATIVE studies
*RANDOMIZED controlled trials
*BLIND experiment
*RESEARCH funding
*TEA
*PLANT extracts
*STATISTICAL sampling
*BREAST tumors
Subjects
Details
- Language :
- English
- ISSN :
- 00223166
- Volume :
- 149
- Issue :
- 4
- Database :
- Academic Search Index
- Journal :
- Journal of Nutrition
- Publication Type :
- Academic Journal
- Accession number :
- 135894294
- Full Text :
- https://doi.org/10.1093/jn/nxy316