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Is Soy Safe

Posted 9/30/2013

Posted in

  Once again, I will begin with an apology for the title of this blog. Yes, I know there should be a question mark after "Is soy safe", but the system won't allow any punctuation. Sigh. There are continuing concerns about the safety of soy, which is a phytoestrogen, for women who have had breast cancer--particularly for women who have had estrogen positive breast cancers.

  The general opinion is that soy products in moderation are not a problem, but that soy supplements should be avoided. Here is a brief article from the New York Times:

Ask Well: Is It Safe to Eat Soy?

Soy has been a dietary staple in Asia for many centuries. Some studies have found that it may
offer some cardiovascular benefits, though the evidence at this point is more suggestive than
As far as any downside, most of the health concerns about soy stem from its concentration of
phytoestrogens, a group of natural compounds that resemble estrogen chemically. Some
experts have questioned whether soy might lower testosterone levels in men and cause
problems for women who have estrogen-sensitive breast cancers. Animal studies have found,
for example, that large doses of phytoestrogens can fuel the growth of tumors.
But phytoestrogens mimic estrogen only very weakly. A number of clinical studies in men
have cast doubt on the notion that eating soy influences testosterone levels to any noticeable
extent. And most large studies of soy intake and breast cancer rates in women have not
found that it causes any harm, said Dr. Anna H. Wu of the Keck School of Medicine at the
University of Southern California. In fact, work by Dr. Wu and others has found that women
who consume the equivalent of about one to two servings of soy daily have a reduced risk of
receiving a diagnosis of breast cancer and of its recurrence.
Still, some women who have developed breast cancer remain particularly worried about
eating soy. But the evidence “is overwhelming that it’s safe,” said Dr. Bette Caan of the Kaiser
Permanente Northern California Division of Research, who has studied soy intake and breast
cancer. “If people enjoy soy as a regular part of their diet,” she said, “there’s no reason to

Last year, in its nutrition guidelines for cancer survivors, the American Cancer Society noted
that eating traditional soy foods — like tofu, miso, tempeh and soy milk — may help lower
the risk of breast, prostate and other cancers. But the guidelines do not recommend soy
supplements, which tend to be highly processed and not very rigorously tested.


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