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Mushrooms & cancer prevention The mushroom has been linked to cancer prevention for some time. The mushroom contains compounds that suppress two enzymes called aromatase and 5-alpha-reductase (Grube 2001; Chen 2006). Aromatase converts androgen to estrogen, which in turn can promote the development of breast cancer, especially in post-menopausal women. Currently aromatase inhibitors are being used in the treatment of estrogen-dependent breast cancer. Aromatase has been found in other cancers, such as ovarian, uterine and prostate cancers and there is speculation that aromatase inhibitors may have a significant role in preventing such cancers (Hong 2006). The enzyme 5-alpha-reductase converts testosterone to dihydro-testosterone and is thought to play a role in the development of prostate cancer and benign prostate enlargement. Research on animal cells in vivo suggest that mushrooms could have a role in protecting men against prostate cancer (Chen 2004). The same team found that button mushrooms reduced prostate tumour size and tumour proliferation, and increased tumour cell death, in mice (Adams 2008). There have been two reviews of research on the potential for mushrooms to reduce the risk of cancer by enhancing the immune system (Borchers 2008; Ziadman et al 2005). The two mushroom components with the most supporting evidence appear to be the beta-glucans and peptide-bound polypeptides. The glucans stimulate the phagocyte system (eg macrophages and monocytes) that consume alien cells. Mushrooms also contain lectins (bio-active proteins), and other compounds that have been strongly linked to a reduction in the risk of cancer and could potentially be helpful in the treatment of cancer (De Mejía 2005, Jedinak 2008). Australian researchers from the University of Western Australia recently studied women in China and found a strong association between mushroom consumption and a decreased risk of breast cancer (Zhang 2009). They undertook a diet and lifestyle interview with 1009 Chinese women with breast cancer and 1009 matched controls. Compared to those having no mushrooms, women eating 10g or more of mushrooms each day reduced their risk of breast cancer by over 60%. This protection was further enhanced if the women also consumed a cup of green tea (1g dried leaves). The effect was seen in both pre- and post-menopausal women. The most common mushroom consumed was the common button mushroom Agaricus bisporus. Two other studies have also shown a link between mushroom eaters and a much lower risk of breast cancer, in the order of 50-60% compared to women who don’t eat mushrooms (Hong 2008, Shin 2010). Because three studies show a similar effect, it has stimulated more human research to see if breast cancer risk reduction in women is specifically due to compounds in mushrooms. |
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