Risks and benefits of dietary isoflavones for cancer

Abstract

A high intake of fruits and vegetables is associated with a lower risk of cancer. In this context, considerable attention is paid to Asian populations who consume high amounts of soy and soy-derived isoflavones, and have a lower risk for several cancer types such as breast and prostate cancers than populations in Western countries. Hence, interest focuses on soyfoods, soy products, and soy ingredients such as isoflavones with regard to their possible beneficial effects that were observed in numerous experiments and studies. The outcomes of the studies are not always conclusive, are often contradictory depending on the experimental conditions, and are, therefore, difficult to interpret. Isoflavone research revealed not only beneficial but also adverse effects, for instance, on the reproductive system. This is also the case with tumor-promoting effects on, for example, breast tissue. Isoflavone extracts and supplements are often used for the treatment of menopausal symptoms and for the prevention of age-associated conditions such as cardiovascular diseases and osteoporosis in postmenopausal women. In relation to this, questions about the effectiveness and safety of isoflavones have to be clarified. Moreover, there are concerns about the maternal consumption of isoflavones due to the development of leukemia in infants. In contrast, men may benefit from the intake of isoflavones with regard to reducing the risk of prostate cancer. Therefore, this review examines the risks but also the benefits of isoflavones with regard to various kinds of cancer, which can be derived from animal and human studies as well as from in vitro experiments.

Perspectives on the Role of Isoflavones in Prostate Cancer

“…The wealth of literature on the anticancer potential of isoflavones, contradictory and counterintuitive at times (99), highlights their enormous potential as nontoxic chemopreventive/therapeutic agents. Moving forward, it seems the best strategy might be to investigate a mixture of these compounds, as opposed to single agents, in more detailed studies.…”

Endocrine Disruptors and Breast Cancer Risk - Time to Consider the Environment

“…Similarly, a Chinese study reported an inverse association between soy food intake and total mortality or cancer occurrence among breast cancer survivors, with a daily isoflavone intake of 62.7 mg and more, regardless of ER status in the breast cancers or tamoxifen use (Shu et al, 2009). Even though these studies are somewhat reassuring, experts believe that the literature is still missing data on the use of isolated isoflavones and supplements as well as the longterm safety of isoflavone supplements and soy extracts in breast tissue, especially among breast cancer patients and survivors (Andres et al, 2011).…”

Combination of low-concentration of novel phytoestrogen (8,9)-furanyl-pterocarpan-3-ol from Pachyrhizus erosus attenuated tamoxifen-associated growth inhibition on breast cancer T47D cells

“…Intentional dietary enrichment or supplement use is common in women seeking an alternative to hormonal replacement therapy and a preventive agent against breast cancer, osteoporosis, or cardiovascular disease [11][12][13] . More than 50% of breast cancer survivors use alternative medicine for hormone replacement therapy [14] , and isoflavones are one of their favorable choices [11,15,16] . On the other hand, the interactive effect of soy components and TAM on breast cancer was not well defined experimentally, and the results have been conflicting [17,18] .…”