The Soy Controversy: Is it Safe?
There has been considerable (and understandable) confusion regarding the net effect soy has on the body. Is it healthy or harmful? Cancer-preventative or cancer-causing? Researchers of the benefits and dangers of soy are divided. Truth is, over the years, medical investigation has—in a very mystifying way—given us reason to consider both sides of the debate to hold some accuracy. Let’s delve into the two opposing positions commonly held, and discover the point at which they both, surprisingly, agree.
The pro-soy
argument is based primarily on statistics that indicate that the Asian
population, which on the whole consumes a great amount of soy products,
experiences a much lower rate of cancer frequency than most other nations [1]. While it is true Asian
countries—in particular Japan—have a reduced rate of some cancers (most
notably, breast, prostrate and bladder cancers), they exceed the U.S.
On the other side of the soy issue
is one unsettling study after another. One such study indicates that although
soy does lower serum cholesterol, it increases Lipoprotein (Lp) levels—which
would heavily contribute to heart disease, not guard against it.[6]
Another study proved that the chance of male infants developing hypospadias (a
reproductive birth defect) doubled if their mothers adhered to a
vegetarian diet (consuming soy) during the pregnancy (an indication of its
endocrine disrupting effects).[7]
Yet other studies: point out the high levels of trypsin inhibitors contained in
soy (trypsin inhibition is known to cause pancreatic damage)[8];
document a clear association of infant formula containing soy with autoimmune
thyroid issues[9]; and warn of the
developmental malignancies and anomalies of the reproductive system that can be
caused by the endocrine disruptors found in soy.[10]
What are we
to do with this conflict in research? Soy has a perplexing suspect profile
indeed! The main risk soy appears to present to the body (based on the
research we have just sifted through) is leveled at the endocrine system: in
specific, the thyroid, hormones and reproductive glands. Interestingly, the
main point upon which both sides of the soy debate converge is within
this vital system as well. Some researchers have come to the conclusion that
soy has a dual nature when it comes to how it affects levels of estrogen (an
incredibly important hormone present in many daily biological processes) in the
body. This is true in many different ways. For example, when estrogen levels in
the body are low, the soy phytoestrogens genistein and daidzein can bind to the
estrogen receptor sites in the body and raise estrogen levels back up, while,
when endogenous estrogen levels are high, the soy phytoestrogens have an
anti-estrogenic effect.4 By the same token, in studies done on
breast cancer, soy phytoestrogens have been shown to stimulate tumor
growth and diminish the effects of tamoxifen (an anti-cancer agent) at
low concentrations, and inhibit tumor growth and increase the
effects of tamoxifen at high concentrations.[11]
Not only this, but they affect the body in such a way that they exacerbate existing
cancer, while being protective against cancer if none yet exists.2 This is all to say that soy affects
hormones in our body in incredibly complex, sometimes beneficial, sometimes
very detrimental ways—by all accounts, in ways we would be wise to be
conscious.
The question in my mind at this
point is this: Is soy’s cholesterol lowering and bone health supportive actions
worth the multitude of debilitating adverse effects that just might be passed
down to the endocrine system if proper monitoring isn’t maintained—causing
imbalances that could manifest in chronic thyroid problems, birth defects, or
even breast cancer? There are safer and—in the big picture—more effective treatment
options for hypercholesteremia (garlic is excellent for this) and osteoporosis
(evening primrose oil and black cohosh, for example)!
So... to be safe, why not throw out the soy milk (in exchange for light and creamy almond milk), tofu (and replace with beans, organic dairy or animal protein) and protein bars packed with soy isolates (and instead go make some yummy homemade protein balls like these)? There's so many other options to choose from!
What side of the fence are you on in the soy discussion? I'd love to hear your thoughts!
What side of the fence are you on in the soy discussion? I'd love to hear your thoughts!
[1] http://www.wcrf.org/int/cancer-facts-figures/data-cancer-frequency-country.
[2] http://healthhubs.net/cancer/cancer-rates-in-the-usa-compared-to-japan/
[3] Shils, M., et al. [2006]. Modern
Nutrition in Health and Disease, pp. 59-592
[4] Ganora, L. [2009]. Herbal
Constituents, pp. 124
[5] http://www.webmd.com/food-recipes/how-good-is-soy?page=2.
[6] Nilhausen K and Meinertz
H. Lipoprotein(a) and dietary proteins: casein lowers lipoprotein(a)
concentrations as compared with soy protein. Am J Clin Nutr
1999;69:419-25.
[7] North K and Golding J. A
maternal vegetarian diet in pregnancy is associated with hypospadias. The
ALSPAC Study Team. Avon Longitudinal Study of Pregnancy
and Childhood. BJU Int 2000 Jan;85(1):107-113.
[8] Brandon DL, Bates DH and
Friedman M. ELISA analysis of soybean trypsin inhibitors in processed foods. Adv Exp Med Biol 1991;289:321-37.
[9] Fort
P
[10] Bar-El DS and Reifen R.
Soy as an endocrine disruptor: cause for caution? J Pediatr Endocrinol Metab
2010 Sep;23(9):855-61.
[11] De Lemos ML. Effects of
soy phytoestrogens genistein and daidzein on breast cancer growth. Anna Pharmacother 2001 Sep;35(9):1118-21.
Image courtesy of: National Center of Complementary and Integrative Health
Image courtesy of: National Center of Complementary and Integrative Health
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