Oral isoflavone supplementation on endometrial thickness: a meta-analysis of randomized placebo-controlled trials

Abstract

BackgroundIsoflavone from soy and other plants modulate hormonal effects in women, and the hormone disorder might result in different caners including endometrial cancer. However, it's effect on the risk of endometrial cancer is still inconclusive. We aimed to assess the effects of isoflavone on endometrial thickness, a risk factor of endometrial cancer in peri- and post-menopausal women.MethodsA meta-analysis of randomized controlled trials was conducted to evaluate the effect of oral isoflavone supplementation on endometrial thickness in peri- and post-menopausal women. Electronic searches were performed on the PubMed, Embase, the Cochrane Library, web of science, CINAHL, and WHO ICTRP to August 1st, 2015. Reviews and reference lists of relevant articles were also searched to identify more studies. Summary estimates of standard mean differences (SMD's) and 95%CIs were obtained with random-effects models. Heterogeneity was evaluated with meta-regression and stratified analyses.ResultsA total of 23 trials were included in the current analysis. The overall results did not show significant change of endometrial thickness after oral isoflavone supplementation (23 studies, 2167subjects; SMD:-0.05; 95%CI:-0.23, 0.13; P=0.60). Stratified analysis suggested that a daily dose of more than 54mg could decrease the endometrial thickness for 0.26mm (10 trials, 984subjects; SMD:-0.26; 95%CI:-0.45, −0.07; P=0.007). Furthermore, isoflavone supplementation significantly decrease the endometrial thickness for 0.23mm in North American studies (7 trials, 726 subjects; SMD:-0.23; 95%CI:-0.44, −0.01; P=0.04), but it suggested an increase for 0.23mm in Asian studies (3 trials, 224 subjects; SMD: 0.23; 95%CI:-0.04, 0.50; P=0.10).ConclusionOral isoflavone supplementation might have different effects in different populations and at different daily doses. Multiple-centre, larger, and long-term trials are deserved to further evaluate its effect.

Soy and Isoflavone Consumption and Multiple Health Outcomes: Umbrella Review of Systematic Reviews and Meta‐Analyses of Observational Studies and Randomized Trials in Humans

“…Soybean isoflavones significantly reduced menopausal hot flash frequency and severity in perimenopausal and postmenopausal women, but it showed slight and slow effects in attenuating menopausal hot flashes compared with estradiol . A daily dose of more than 54 mg isoflavone could decrease the endometrial thickness for 0.26 mm . It may also improve subjective symptoms and objective signs of vaginal atrophy in menopause .…”

Soy and Health Update: Evaluation of the Clinical and Epidemiologic Literature

“…Interestingly, a recently published meta-analysis of the clinical data found that when all studies ( n = 23; 2167 participants) were included in the analysis there was no effect of isoflavones on endometrial thickness overall whereas there was a significant ( p = 0.04) decrease in thickness when considering only the seven North American trials which involved 726 women [433]. On the other hand, there was small increase in thickness among women involved in the three Asian trials but none of these studies actually intervened with soybean-derived isoflavones.…”

Efeitos das terapias na menopausa: uma revisão narrativa da literatura

“…A via transdérmica mostra menor risco de tromboembolismo venoso do estradiol quando comparado com a via oral, mostrando ser a mais segura. Por outro lado, a administração, por via oral, gera um maior impacto na redução dos níveis do colesterol LDL, o que é uma vantagem na mulher com hipercolesterolemia e triglicérides normais, levando-se em conta que o último pode elevar-se com a medicação 16,17 .…”

“…A via de administração não oral do estradiol e da progesterona impede o metabolismo de primeira passagem pelo fígado, ocasionando, assim, menor potencial para a formação das proteínas hepáticas, fatores de coagulação e perfil metabólico, o que pode ser mais favorável em termos de riscos cardiovasculares e fenômenos tromboembólicos 15,16,17 .…”

“…No esquema cíclico, a mulher apresenta sangramento ao final de cada ciclo de progesterona e, no contínuo, a grande maioria entra em amenorreia e quando isso não ocorre, devem-se investigar as condições do endométrio. De qualquer forma, a escolha do esquema é sempre individualizada, priorizando-se a vontade da paciente e o tempo de menopausa 17 .…”