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According to Dr Megan Rossi, Gut nutrition expert, there is solid evidence to show that enjoying foods rich in soy is actually associated with lower risk of developing breast cancer. And, if you’ve had breast cancer or currently have it, eating such foods is associated with better outcomes.
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Some old studies in mice showed that mice who ate soy had increased risk of breast cancer cells, versus those who did not.
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This led to a popular hypothesis that soy is harmful.
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But we know now that mice process soy in a very different way than humans. Humans break down the plant chemicals in soy (phytoestrogens) into two main compounds. These are similar to oestrogen - but have much weaker effects.
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Mice, however, metabolise soy in such a way which means that they are exposed to much higher levels of phytoestrogens than humans. (The reason this matters is that certain types of breast cancer have been traced to increased oestrogen in the body).
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Now, because the compounds produced in humans when we break down soy are similar to oestrogen, they have actually been shown to help block the action of oestrogen, as they can bind to cancer cells. So eating soy is thought to reduce your breast cancer risk through that mechanism.
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