Brian D. Lawenda, M.D.: A question that comes up often is whether soy-based foods have any
beneficial effects in terms of reducing the risk of developing cancer or potentially detrimental
effects in terms of increasing risk of cancer and so one of the things that is interesting
is that soy itself is genetically modified 95% of the time.
There was a study that came out a few years ago looking at actually genetically modified
corn not soy per say what they found is that when you fed a rat of particular type of genetically
modified corn, it developed cancers at a much greater rate than those that would not getting
genetically modified corn.
Additionally, when the rats were consuming at the herbicide that is typically spread
on genetically modified corn they actually found that they also developed breast cancers
at a significantly higher rate than those that were not getting the herbicide.
So, we know that the soy is spread with the same type of herbicide and so one might guess
that something similar could happen, but in fact what we are finding is that there really
does not appear to be any correlation in human studies with the development of cancer or
reduction in cancer risk in most large studies.
In fact what we actually see is potentially even a reduction slightly in the risk of developing
breast cancer for example particularly in Asian patients, or Asian population.
So, it’s something is very interesting, its area of a lot of controversy, we just
don’t seem to find that there is an increase risk or decrease risk in most populations
based on moderate intake of soy which somewhere between one to maybe up to three servings
of soy per day.
Now that’s taking whole food version of soy like tofu, edamame, and soy milk.
We are not talking about the extract versions of soy that are often found in things such
as soy burgers and soy hot dogs, and soy protein powders some of those things particularly
in the laboratory have been shown the increase the risk of developments of variety of cancers.
It maybe because those particular soy extracts are more potent in terms of their estrogen
like abilities to stimulate the estrogen receptor on cells which potentially could serve as
a growth factor for cancer cells that are sensitive to estrogen.
So, interesting, there have been studies looking also at populations of ladies who have had
breast cancer and the breast cancer survivors who then are basically soy consumers versus
less soy consumers and they found actually that in that population of people who consumed
greater quantities of soy even though they were counseled to not consume large quantities
of soy, had actually a lower risk of developing a breast cancer recurrence.
So, it seemed like might maybe it was protective in that regard for that, but that is typically
was in an Asian population and there have been some follow-on studies of that, so we
are still learning more about this area of controversy.
In terms of prostate cancer patients, soy seems to actually potentially slow the rise
of the PSA which is the blood test looking at prostate cancers and that may or may not
correlate with growth of the cancer in terms of slowing the growth down.
It is something of controversy.
It’s an area that is active research.
My answer is basically soy does not appear to increase or significantly decrease the
risk of breast cancer or other cancers.
So, I think it is relatively safe in standard quantities that people will be having some
more between one to three servings per day.
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