CARDIOLOGY, PRIMARY CARE AND NUTRITION

Blogpost: Soy Misconceptions

I recently spent the day at a local health fair promoting the benefits of plant based nutrition.  Soy was brought up more than once as a reason for not being plant based.  Apparently, there must be a rule somewhere that makes soy a mandatory ingredient in a vegan diet.  I have not been able to locate the source of such a popular belief.  But, there are lot of misconceptions about the safety of soy that I would like to address.  I find it ironic that people are afraid to consume soy, but they happily consume animals who spent their lives consuming hundreds of pounds of the stuff.  Processed baked goods are dandy despite containing soy lecithin, which is a fat in soy used as a binder.  There is soybean oil in Twinkies as well as most boxed baked goods.  I am sure the gentleman claiming to live on 3 cartons a week would be interested in that fact.  I digress.

But those are not the products people are worried about.  It is soy milk and the dreaded, crinkle your nose, and say ooo, “tofu” that gets people all bothered.  Isn’t soy milk processed? Asked the Twinkie eating gentleman.  It is if you consider homemade chicken noodle soup processed.  Soy milk is made by soaking and dehulling soybeans and then blending into a liquid.  The liquid is boiled for twenty minutes and you now have soy milk.  What about tofu?  This time you start with soy milk and add calcium sulfate or magnesium sulfate and it thickens as similarly done in making cottage cheese.  Only with cottage cheese you need to take a liquid full of growth hormones and bacteria and add the emulsifiant.  It is funny that people are usually ok with Miso soup but not tofu.  Miso is fermented soybean paste.  What about tempeh you ask?  It is cooked soybeans fermented with a rhizome into a cake like form, not unlike making hard cheese.  But tempeh does not contain salt, hormones, growth factors, and cholesterol that hard cheese offers.  Isn’t it funny that we Americans were quick to adopt Kung Pao chicken and sushi, but not the healthy soy products that give Asians a much lower incidence of breast and prostate cancer?

The big fear is that  the soy isoflavone, genestein, is cancer causing.  The short answer is that it is a phytoestrogen that blocks the estrogen receptors.  There are actually two estrogen receptors, alpha and beta.  Soy attaches to beta receptors primarily.  The estrogen beta receptors are found in breast tissue which is believed to be the reason why soy intake has been shown to be protective against breast and prostate cancer.  There have been 5 large studies with over 10,000 women looking at breast cancer recurrence with soy.  Those consuming soy lived longer.  It appears that the dreaded mutated BRCA gene is  actually turned off with the consumption of soy.  There was a 27% decrease in breast cancer associated with normal BRCA genes and a 73% decrease in cancer in those with a mutated BRCA gene.  On the other hand, meat intake was associated  with doubling the BCRA gene mutations,  increasing the breast cancer by 97% when compared to those with a normal BRCA gene.  So if you have had genetic testing and have the mutated BRCA gene, consuming animal protein is like holding a handgrinade with the pin out and hoping it does not explode.  What about the alpha receptor? It turns out those studies showing that soy promotes breast cancer were in mice which metabolize soy different from humans because they have more alpha receptors.  A human would have to consume 58 cups of soy milk daily to get enough alpha receptor stimulation to cause a problem.  The liver is responsible for producing clotting factors and contain mainly alpha estrogen receptors.  This is why estrogen replacement hormones cause increased blood clots associated with strokes, heart attacks and pulmonary emboli but soy does not.  Bone cells contain beta estrogen receptors.  In a study looking at bone density over 2 years, those taking nothing lost bone density, those taking progesterone lost less and those drinking 2 glasses of soy milk daily had an increase in bone density compared to the start of the study.  A single serving of soy protein a day or 5-7 grams was associated with a decrease in bone fracture rate .

We know that dairy promotes prostate tumor growth, but soy milk and tofu resulted in a 30% reduction in prostate cancer cell growth.  It turns out the soy milk and tofu are actually a little more potent than tempeh with regards to prostate cancer.  So mix up your soy products.

The incidence of a true soy allergy is about 1 in 2000 people which is 40 times less than a milk allergy.  If you are concerned with genetically modified organisms or GMOs then stay away from animal products.  GMO soy is the predominate form of soybeans given to livestock.

We know that there is about an 8% increase in stomach cancer with each extra gram of salt intake and this is compounded eating meat.  Miso is fermented with salt but the benefits of the soy seem to outweigh the salt added in fermentation and actually has shown a decrease in stomach cancers.

So how do you incorporate more GMO free soy in your diet.  Drink and cook with soy milk.  Try coconut encrusted baked tofu with your stir-fry.  Miso soup with onion, garlic, ginger, and mushrooms is an antioxidant, phytonutrient powerhouse.  Tempeh can be substituted for bacon in a BLT or corned beef in a Reuben or added to a breakfast vegetable scramble. Creamy deserts and fillings can be made with silken tofu.

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Fan S, et al.  Br J Cancer 2006 Feb13; 94(3) 407-26.

JAMA 2009 Dec9;302(22)243-246

Zhong X, et al. Arch Int Meds 2005 Sept 12; 165 (16); 1890-5.

 

2 Comments
  1. Reply
    Janet

    Great article; thank you!

  2. Reply
    Deidre

    This was a terrific peice! Thanks!

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