Isoflavone consumption and risk of breast cancer: A dose-response meta-analysis of observational studies

ArticleinAsia Pacific Journal of Clinical Nutrition 22(1):118-27 · January 2013with12 Reads
DOI: 10.6133/apjcn.2013.22.1.16 · Source: PubMed
Abstract
Epidemiologic studies that examine whether isoflavone consumption protects against breast cancer have yielded inconsistent results. The controversy focuses on the effects of the menopausal status and exposure dose of isoflavone. We aim to conduct a meta-analysis on the association between isoflavone intake and breast cancer risk by comprehensively assessing isoflavone exposure in the targeted populations. We searched PUBMED and EMBASE databases for case-control and cohort studies that assess the association between isoflavone intake and breast cancer risk. We extracted relative risks (RR) and odds ratios (OR) of different reported categories of isoflavone intake from each study. Fixed- or random-effects models were used to summarize dose-response data. Twenty-two studies were selected for the meta-analysis. Overall, the results showed that isoflavone reduced the breast cancer risk (a combined RR/OR of 0.68, 95% CI: 0.52-0.89) in Asian populations rather than Western populations (a combined RR/OR of 0.98, 95% CI: 0.87, 1.11) for the high-dose category. Further analysis showed that the intake of isoflavone in postmenopausal Asian women 0.46 (95% CI: 0.28-0.78) was better than premenopausal 0.63 (95% CI: 0.50-0.80) but similar in postmenopausal Western women 1.00 (95% CI: 0.98-1.02) and premenopausal 0.99 (95% CI: 0.87-1.12). Exposure to high isoflavone may be associated with a reduced breast cancer risk in Asian populations, especially in postmenopausal women. However, no significant difference in the studies of Western populations may be due to the low intake of isoflavone levels.
    • "In this case, the experimental study in cell culture or animal modes might be a more direct way to assess the anticancer efficacy of natural polyphenols as well as to examine the possible mechanisms involved in this process. [14] gastric cancer flavonoids case-control study no significant association [16] flavonoids case-control study 0.33 (0.15–0.73) [15] colorectal cancer flavonoids cohort study no significant association [19] flavonoids and lignans case-control study total flavonoids 0.59 (0.35–0.99); lignans 0.59 (0.34–0.99) [18] polyphenols case-control study no significant association [20] isoflavones meta-analysis 0.76 (0.59–0.98) [17] HCC flavanols cohort study 0.62 (0.33–0.99) [22] breast cancer flavonoids meta-analysis flavonols 0.88 (0.80–0.98); flavones 0.83 (0.76–0.91); no significant association for total flavonoids or other subclasses [23] isoflavones meta-analysis 0.68 (0.52–0.89) [25] flavanols cohort study 0.81 (0.67–0.97) [26] prostate cancer flavonoids cohort study 1.15 (1.04–1.27) [28] flavonoids cohort study total catechin 0.73 (0.57–0.95); epicatechin 0.74 (0.57–0.95); kaempferol 0.78 (0.61–1.00); myricetin 0.71 (0.55–0.91) [27] "
    [Show abstract] [Hide abstract] ABSTRACT: There is much epidemiological evidence that a diet rich in fruits and vegetables could lower the risk of certain cancers. The effect has been attributed, in part, to natural polyphenols. Besides, numerous studies have demonstrated that natural polyphenols could be used for the prevention and treatment of cancer. Potential mechanisms included antioxidant, anti-inflammation as well as the modulation of multiple molecular events involved in carcinogenesis. The current review summarized the anticancer efficacy of major polyphenol classes (flavonoids, phenolic acids, lignans and stilbenes) and discussed the potential mechanisms of action, which were based on epidemiological, in vitro, in vivo and clinical studies within the past five years.
    Full-text · Article · Aug 2016
    • "Conversely, a non-Asian diet contains less than 1g of soy protein per day [9]. Due to these different food preferences, an inverse association between soy isoflavone intake and breast cancer risk has been demonstrated mostly for Asian populations and not for Western populations [10,11]. These observations have sparked a sustained interest in soy isoflavones as a promising therapeutic option in breast cancer chemoprevention. "
    [Show abstract] [Hide abstract] ABSTRACT: The potential benefit of soy isoflavones in breast cancer chemoprevention, as suggested by epidemiological studies, has aroused the interest of numerous scientists for over twenty years. Although intensive work has been done in this field, the preclinical results continue to be controversial and the molecular mechanisms are far from being fully understood. The antiproliferative effect of soy isoflavones has been commonly linked to the estrogen receptor interaction, but there is growing evidence that other pathways are influenced as well. Among these, the regulation of apoptosis, cell proliferation and survival, inhibition of angiogenesis and metastasis or antioxidant properties have been recently explored using various isoflavone doses and various breast cancer cells. In this review, we offer a comprehensive perspective on the molecular mechanisms of isoflavones observed in in vitro studies, emphasizing each time the dose-effect relationship and estrogen receptor status of the cells. Furthermore, we present future research directions in this field which could provide a better understanding of the inner molecular mechanisms of soy isoflavones in breast cancer.
    Full-text · Article · Jan 2016
    • "Isoflavones have been shown to be effective against these symptoms because of their pro-estrogenic effects [1,9101112. On the other hand, isoflavones are also known to act prophylactically against breast cancer through their anti-estrogenic effect [13,14]. Isoflavones are usually present in the form of glycosides in soybeans and unfermented soy foods [15,16]. "
    [Show abstract] [Hide abstract] ABSTRACT: The various beneficial effects of soybeans, which are rich in phytochemicals, have received much attention because of increasing health awareness. Soy milk that has been fermented using lactic acid bacteria has been used to prepare cheese-like products, tofu (bean-curd), and yogurt-type products. However, the distinct odor of soybeans has limited the acceptance of such foods, particularly in Western countries. In Japan, while tofu and soy milk have long been habitually consumed, the development of novel, palatable food products has not been easy. The unpleasant odor of soy milk and the absorption efficiency for isoflavones can be improved using a recently developed fermented soy milk beverage. Cancer has been the leading cause of death, and breast cancer is the most common malignancy among women. The most common type of breast cancer is estrogen-dependent, and the anti-estrogenic effects of isoflavones are known. The present review focuses on the characteristics of soy milk fermented using probiotics, an epidemiological study examining the incidence of breast cancer and soy isoflavone consumption, and a non-clinical study examining breast cancer prevention using fermented soy milk beverage.
    Full-text · Article · May 2015
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