Friday, October 21, 2011

Can too much of a good thing be bad for you? The deal with soy

Recently a friend asked for some healthy eating tips, and specifically what to do about eating soy. Is it good for you or is it evil? Since I thought it was an excellent question, I figured I would share my findings on the matter.

First of all, soy is a great yummy source of protein and has been linked to reducing the risk of heart disease, osteoporosis, and cancer! Soy has a group of plant estrogens (yes, the hormone. I'll get to that in a bit) called isoflavones. And these isoflavones, namely genestin and daidzen (who comes up with these names?!), are the good stuff that protects your health.

But before you start eating soy with every meal, remember how I said that soy has estrogen? Yeah, well not quite the estrogen that your body produces, but a phytoestrogen, a plant produced compound that mimics the estrogen found in your body. And as you can imagine, pumping your body full of hormones probably isn't the best idea. Animal studies have shown that consuming large quantities of isoflavones develop liver, thyroid and reproductive problems. EEK!

What to do? Asian cultures eat plenty of soy and they are known for their longevity, so what gives? The difference is that they eat WHOLE foods - tofu, edamame, tempeh, and miso - not the super processed stuff that is found in our supermarkets like soy dogs, ice cream, and cookies. These processed foods extract the soy protein isolate and aren't filled with all the good stuff that you can get from soy.

Eating soy in moderation is indeed good for your health. Just make sure it is in whole form, not too much (a serving or two a day), and definitely don't take any isoflavone supplements (again, processed soy is bad). If you are pregnant or at risk for developing estrogen sensitive tumors like breast and ovarian cancer, try not to eat to much soy in any form. In our veggie household, we eat soy (tempeh or tofu) as a staple in our dinner probably twice a week, and I try to buy other "meatless" options that are veggie or gluten based instead of soy. My veggie friend switched from soy milk to almond milk (especially when trying to conceive and pregnant), and for those that are lactarded (such as myself), lactose free milk is a great alternative.

So go ahead, have that edamame with your lunch!


  1. Start off with a healthy diet by eating less processed foods. Soy is also a great alternative.

  2. Absolutely Miranda- my first rule to eating is if you can't pronounce it, don't eat it!

  3. I didn't know Soy contained Physoestrogen. I always thought Soy is good for you because it came from plants.

  4. As they adage goes, everything in moderation! Even pretty innocuous things, like flaxseeds (also a source of phytoestrogens, albeit in a different form), can be bad if you have too much. Your diet should always be colorful and varied - a little bit of this, a little bit of that, and you should be all set!

  5. I wonder how male bodybuilders would react to this news that eating soy would produce lots of estrogen-like substances in their bodies. It will be quite amusing.


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