Tofu and risk of breast cancer in Asian-Americans

Department of Preventive Medicine, University of Southern California, Los Angeles 90033-0800, USA.
Cancer Epidemiology Biomarkers & Prevention (Impact Factor: 4.13). 12/1996; 5(11):901-6.
Source: PubMed

ABSTRACT Breast cancer rates among Asian-Americans are lower than those of US whites but considerably higher than rates prevailing in Asia. It is suspected that migration to the US brings about a change in endocrine function among Asian women, although reasons for this change remain obscure. The high intake of soy in Asia and its reduced intake among Asian-Americans has been suggested to partly explain the increase of breast cancer rates in Asian-Americans. We conducted a population-based case-control study of breast cancer among Chinese-, Japanese-, and Filipino-American women in Los Angeles County MSA, San Francisco Oakland MSA, and Oahu, Hawaii. Using a common questionnaire which assessed frequency of intake of some 90 food items, 597 Asian-American women (70% of those eligible) diagnosed with incident, primary breast cancer during 1983-1987 and 966 population-based controls (75% of those eligible) were interviewed. Controls were matched to cases on age, ethnicity, and area of residence. This analysis compares usual adult intake of soy (estimated primarily from tofu intake) among breast cancer cases and control women. After adjustment for age, ethnicity and study area, intake of tofu was more than twice as high among Asian-American women born in Asia (62 times per year) compared to those born in the US (30 times per year). Among migrants, intake of tofu decreased with years of residence in the US. Risk of breast cancer decreased with increasing frequency of intake of tofu after adjustment for age, study area, ethnicity, and migration history; the adjusted OR associated with each additional serving per week was 0.85 (95% CI = 0.74-0.99). The protective effect of high tofu intake was observed in pre- and postmenopausal women. This association remained after adjustment for selected dietary factors and menstrual and reproductive factors. However, this study was not designed specifically to investigate the role of soy intake and our assessment of soy intake may be incomplete. We cannot discount the possibility that soy intake is a marker of other protective aspects of Asian diet and/or Asian lifestyle.

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    • "μmol/day; O-Dma~0.03 μmol/day) (Adlercreutz et al. 1986). In addition, Wu et al. have demonstrated that the increased intake of tofu associates closely with the reduced risk of breast cancer in a case–control study of pre-and post-menopausal Asian-American women (Wu et al. 1996). Men living in Eastern countries having more soyfoods intake exhibit much higher levels of isoflavone and lower prostate cancer mortality in comparison with those living in Western countries. "
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    ABSTRACT: Soybean products (soyfoods), reported as potential functional foods, are implicated in several health-enhancing properties, such as easing the symptoms of postmenopausal women, reducing the risk of osteoporosis, preventing cardiovascular disease, and antimutagenic effects. Isoflavone, for example, is one of the most important compounds abundantly found in soybean, mainly accounting for the health-enhancing properties as mentioned earlier. However, most biological activities of isoflavones are mainly attributed to their aglycone forms. It has also been demonstrated that isoflavone aglycones are absorbed faster and in greater amount than their glycosides in human intestines. Fortunately, deglycosylation of isoflavones can be achieved during fermentation process by several strains such as lactic acid bacteria, basidiomycetes, filamentous fungus, and Bacillus subtilis with their β-glucosidase activity. This article presents an overview of soybean's chemistry, application, state-of-the-art advances in soybean fermentation processing and products as well as their applications in food and pharmaceutical industries. Different compounds, such as isoflavone, dietary fibers, and proteins which exhibit significant bioactivities, are summarized. The roles of different microorganisms in bioconversion and enhancement of bioactivities of fermented soybean are also discussed.
    Applied Microbiology and Biotechnology 08/2012; 96(1):9-22. DOI:10.1007/s00253-012-4330-7 · 3.34 Impact Factor
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    • "Although most of the epidemiological data regarding genistein’s anticancer activity are focused on prostate cancer, the effects of this natural product have also been studied in the context of other cancer types. In breast cancer, genistein consumption has been associated with a decrease in disease incidence [7, 8], potentially as a result of genistein’s ability to mimic natural estrogens (see Section 2.1), which are known to play a role in breast cancer progression. These studies have not specifically looked at factors related to the metastatic incidence of breast cancer. "
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    CANCER AND METASTASIS REVIEW 09/2010; 29(3):465-82. DOI:10.1007/s10555-010-9238-z · 7.23 Impact Factor
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    • "Phytoestrogens are a class of plant-derived substances that are structurally and/or functionally similar to 17β-estradiol (E2) [7]. Interest in phytoestrogens, more particularly soy, has been instigated by epidemiologic studies that have suggested a low incidence of breast cancer in Asian countries that have high soy intake [8,9]. It has also been suggested that soy isoflavones may influence breast cancer risk via their anti-proliferative, anti-angiogenic, anti-oxidative and anti-inflammatory properties, but the possible mechanisms of phytoestrogen actions in breast cancer prevention remained inconclusive. "
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