If women would like to hedge on the side that it may be protective, they should eat soy foods like soy milk, soy nuts and tofu.
These questionnaires don't capture everything. Reported intake is not a good estimate of real intake.
But there are no studies that have followed women long enough to solidify this.
Given the complicated interplay of events and factors that go into developing cancer, we shouldn't be surprised that one food doesn't give us a clear signal. We shouldn't expect it to be so simple.
At this point, women should not be taking high-dose soy supplements, especially those who are breast cancer survivors and women at increased risk for the disease. We don't have long-term data on the effects of these supplements, and there is some evidence that they could be harmful.
When you put it all together, we came up with evidence of a small protective effect but a lot of reasons to be a little wary of how accurate that effect may be.
At the time most of these studies were done, few Western women were eating tofu, but many were getting soy without noticing it.
