ASK THE DOCTOR by Dr. Chad Larson
[Q&A] Breast Cancer And Soy
Submitted by: Shelly G.
Q: What is
the deal with estrogen and breast cancer? And how do phytoestrogens
from soy affect that risk?
A: The National
Toxicology Program of the US Public Health Service recently
added conjugated estrogens to the known to be human carcinogens
list. Furthermore, some estrogen's are more carcinogenic than
others. There are three main estrogen's: estradiol, estrone,
and estriol. These three are further broke down into three
families of estrogen metabolites. These families are the 2-H
estrogens, the 4-H estrogens, and the 16-H estrogens. The
4-H and 16-H estrogens are believed to the more carcinogenic.
The 2-H estrogens are believed to be anticarcinogenic. Therefore,
the more important issue is the ratio of the 2-H and the 16-H
estrogens. Women who metabolize through the 16-H pathway may
be at a higher risk for breast cancer than women who metabolize
more estrogen through the 2-H pathway.
You may be wondering if you can increase your body's metabolism
of estrogen through the 2-H pathway. The answer is yes! Whew!
Last year in the New England Journal of Medicine it was noted
that environment, diet, and lifestyle play significant roles
in modulating estrogen metabolism.
This leads us to the second part of your question. Do phytoestrogens
from soy affect the risk of breast cancer? First of all, I
agree with Jeffrey Bland, Ph.D., when he says we need to drop
the term phytoestrogen and replace it with phyto-hormone modulator.
They are not estrogens at all. Isoflavones (often referred
to as phytosetrogens) from soybeans need to be considered
adaptogens for managing estrogen balance. In other words,
they help increase estrogen in individuals with a low-estrogen
imbalance and they decrease estrogen in those with a high-estrogen
imbalance. The soy isoflavones genistein and daizein are the
most studied estrogen-modulating compounds from plants. Isoflavones
from red clover and the Kudzu vine have also been shown to
have estrogen activity-modulating effects. In addition to
soy, red clover, and the Kudzu vine; chasteberry (Vitex agnus-castus
L.), black cohosh (cimicifuga racemosa), and essential fatty
acids (such as flax and fish oil), have been demonstrated
historically to have hormone activity-modulating affects.
Lastly, another way to promote the 2-H pathway by lowering
the more carcinogenic 16-H pathway is administration of the
phytonutrient indole-3-carbinol (I-3-C).
Fortunately, your 2-H to 16-H ratio can be evaluated by a
simple urine test and we can formulate an individually-tailored
program for you including diet, nutrition, and lifestyle.
We live in bodies where all the systems are very interrelated
in a web-like balance of interactions. We cannot just listen
to one instrument when addressing the human body but rather
have to respect and consider the entire symphony. As usual,
I would recommend a consultation for an individualized, comprehensive
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