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

Hamed Samavat, Anna H. Wu, Giske Ursin, Carolyn J Torkelson, Renwei Wang, Mimi C. Yu, Douglas Yee, Mindy S Kurzer, Jian Min Yuan

Research output: Contribution to journalArticle

Abstract

Background: 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. Objective: We investigated the effects of decaffeinated green tea extract (GTE) on circulating sex hormones and insulin-like growth factor (IGF) proteins. Methods: 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-3gallate 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. Results: 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. Conclusion: 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.

Original languageEnglish (US)
Pages (from-to)619-627
Number of pages9
JournalJournal of Nutrition
Volume149
Issue number4
DOIs
StatePublished - Apr 1 2019

Fingerprint

Catechin
Gonadal Steroid Hormones
Somatomedins
Tea
Randomized Controlled Trials
Breast Neoplasms
Estradiol
Proteins
Placebos
Capsules
Catechol O-Methyltransferase
Sex Hormone-Binding Globulin
Insulin-Like Growth Factor Binding Protein 3
Androstenedione
Estrone
Testosterone
Analysis of Variance
Genotype
Outcome Assessment (Health Care)
Clinical Trials

Keywords

  • Breast cancer
  • Catechins
  • Green tea extract
  • Insulin-like growth factors
  • Postmenopausal women
  • Sex hormones

PubMed: MeSH publication types

  • Journal Article

Cite this

@article{70feb6f4e5ac4122b18c9127d92d4a12,
title = "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",
abstract = "Background: 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. Objective: We investigated the effects of decaffeinated green tea extract (GTE) on circulating sex hormones and insulin-like growth factor (IGF) proteins. Methods: 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-3gallate 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. Results: 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. Conclusion: 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.",
keywords = "Breast cancer, Catechins, Green tea extract, Insulin-like growth factors, Postmenopausal women, Sex hormones",
author = "Hamed Samavat and Wu, {Anna H.} and Giske Ursin and Torkelson, {Carolyn J} and Renwei Wang and Yu, {Mimi C.} and Douglas Yee and Kurzer, {Mindy S} and Yuan, {Jian Min}",
year = "2019",
month = "4",
day = "1",
doi = "10.1093/jn/nxy316",
language = "English (US)",
volume = "149",
pages = "619--627",
journal = "Journal of Nutrition",
issn = "0022-3166",
publisher = "American Society for Nutrition",
number = "4",

}

TY - JOUR

T1 - 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

AU - Samavat, Hamed

AU - Wu, Anna H.

AU - Ursin, Giske

AU - Torkelson, Carolyn J

AU - Wang, Renwei

AU - Yu, Mimi C.

AU - Yee, Douglas

AU - Kurzer, Mindy S

AU - Yuan, Jian Min

PY - 2019/4/1

Y1 - 2019/4/1

N2 - Background: 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. Objective: We investigated the effects of decaffeinated green tea extract (GTE) on circulating sex hormones and insulin-like growth factor (IGF) proteins. Methods: 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-3gallate 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. Results: 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. Conclusion: 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.

AB - Background: 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. Objective: We investigated the effects of decaffeinated green tea extract (GTE) on circulating sex hormones and insulin-like growth factor (IGF) proteins. Methods: 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-3gallate 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. Results: 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. Conclusion: 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.

KW - Breast cancer

KW - Catechins

KW - Green tea extract

KW - Insulin-like growth factors

KW - Postmenopausal women

KW - Sex hormones

UR - http://www.scopus.com/inward/record.url?scp=85064886631&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85064886631&partnerID=8YFLogxK

U2 - 10.1093/jn/nxy316

DO - 10.1093/jn/nxy316

M3 - Article

C2 - 30926986

AN - SCOPUS:85064886631

VL - 149

SP - 619

EP - 627

JO - Journal of Nutrition

JF - Journal of Nutrition

SN - 0022-3166

IS - 4

ER -