Is edamame (soy beans) safe for breast cancer survivors?
I am a 46 year old woman and was diagnosed with DCIS breast cancer in Dec. of 2007. I had a lumpectomy and a sentinal lymphectomy followed by 30 treatments of radiation. In May of 2008 I had an oovarectomy because of many complicated cysts on both ovaries. I had started taking Tamoxifen in March 2008 and was taken off of it by my oncologist in June 2008. She thought it wasn't necessary because I am without estrogen producing ovaries now.
I have recently discovered edamame and love it! It has helped immensely with the hot flashes and night sweats I've been dealing with.
I was hoping you could elaborate on the effects of edamame on women in my situation. I understand it is good for young girls but what about a woman of 46 who was suddenly thrown into menopause?
Dr. Gourmet Says...
What we know about soy and breast cancer has been a little difficult to interpret because most of the research offers us only indirect evidence. Ideally, research would be performed that would have women eat more soy products after being diagnosed with breast cancer and compare them with those without disease to see if there are higher or lower rates of recurrence. It's unlikely that we'll have that sort of information anytime soon.
It is the phytoestrogens in soy that appear to have anti-estrogenic properties. As such the belief that a diet high in soy might prevent breast cancer has some merit. It is those properties that appear to help some women with menopausal symptoms.
Research we have now indicates that you should be safe eating soy products. Most of these data are epidemiologic studies performed in Japan where soy consumption is high. These are not studies of causality, however. They are too general to definitively show a diet high in soy reduces breast cancer risk. The most focused research does appear to indicate a diet high in soy might reduce the risk (the key word is might).
The studies in animals are mixed with some studies showing the possibility of increase in tumors and others not showing this. Most of the more recent studies come down on the side of soy being safe. There have also been studies in rats given tamoxifen (a common anti-estrogen used to prevent breast cancer recurrence) that show adding soy to the diet reduces the development of tumors.
It appears that it's reasonable for you to have a serving of edamame daily.
Thanks for writing,
Timothy S. Harlan, M.D.
Dr. Gourmet