Soy Epilogue: GMO Soy

Yesterday’s post about soy looked at the claims that soy is not good for you and then compared the claims to the science. The claims, as is often the case, were found lacking. But the post got long and I did want to spend a little time talking about genetically modified (GMO) soy because it’s an important part of the soy discussion.

I will admit that I’m not an expert on genetically modified crops, in fact, far from it. It was not a topic that I had given much consideration when I was working as a surgeon; after all, learning better and safer ways to do surgery seemed more pressing that what the farmers were planting. But as I learn more and more about genetically modified crops, I am definitely concerned that this is another example of corporate greed getting the better of common sense. For a well reasoned discussion of genetically engineered crops, I refer you to this article from the Union of Concerned Scientists.

Our old friend the USDA reports that about 90% of the soy beans grown in the U.S. are genetically modified. Moreover, almost all of that 90% are the same genetic modification called “Roundup Ready” from the Monsanto corporation. Monsanto, a multinational agrochemical and agrotech company is, of course, the maker of the ubiquitous herbicide Roundup, so frequently advertised for household use to rid your lawn and garden of those pesky weeds. But, as anyone who has used it around the house knows, the over spray from Roundup is an indiscriminate plant killer. Since American farmers use quite a bit of Roundup to prevent weeds, the folks at Monsanto came up with a plan to genetically modify some common crops so that they are resistant to Roundup, meaning that farmers could spray directly on the crops and kill the weeds, but the crop itself would not be affected. Sounds like a great plan; what could possibly go wrong?

Well, Roundup Ready soy turns out to be different than non-GMO soy in more ways than just being resistant to Roundup. This 2014 article from Food Science analyzes the compositional differences between organic, conventional, and GMO soy and came to the following conclusions (glyphosate is the active compound in Roundup, AMPA is what glyphosate breaks down into):


  • Glyphosate tolerant GM soybeans contain high residues of glyphosate and AMPA.
  • Soybeans from different agricultural practices differ in nutritional quality.
  • Organic soybeans showed a more healthy nutritional profile than other soybeans.
  • Organic soy contained more sugars, protein and zinc, but less fibre and omega-6.
  • This study rejects that GM soy is “substantially equivalent” to non-GM soybeans.

So, in a nutshell, Roundup Ready soy beans have less of what makes soy such a nutritionally balanced food in exchange for high residues of glyphosate and AMPA. A February 2016 article in Environmental Health entitled “Concerns over use of glyphosate-based herbicides and risks associated with exposures: a consensus statement” does a nice job covering the issues of glyphosate exposure and human health including, but not limited to, the fact that the World Health Organization has recently upgraded glyphosate to “probably carcinogenic to humans”. So this is not an insignificant point.

It’s pretty clear that the 10% of soybeans that are not GMO are clearly labelled and sold as such. Any trip to Whole Foods or a similar store will  show items like these tofu packages, both clearly marked as organic and non-GMO. organic_firmorganic-extra-firm-tofu So what happens to all that Roundup Ready soy? Where does the 90% go? Most of it is processed and goes into one of two products: soy meal, which is almost exclusively fed to livestock and oil, which is the primary ingredient in most “Vegetable Oils” you might buy at the supermarket. Wesson Vegetable Oil and Crisco Vegetable Oil are 100% soy, whereas Mazola Vegetable Oil is a soy/canola blend, with soy being the larger component. Fortunately, it appears that glyphosate is not soluble in oil, meaning that it concentrates in the soy meal and not the oil.

So what about all the glyphosate being fed to livestock? This 2012 article in Current Microbiology documents that glyphosate is toxic to some bacteria in the gut of chickens, but not to others, which has the significant potential to change the gut microbiome. And, you can be sure, if it can happen to chickens it can happen to cows, pigs, and people. The whole concept and understanding of the human gut microbiome is an exciting and rapidly evolving field of study. A PubMed search of “human gut microbiome review” will get you about 12oo papers written in the last 5 years. And while there may be opportunities to alter the microbiome in positive ways to help treat a wide spectrum of diseases that would seem to have no obvious connection to the gut, it seems equally clear that to have a probable human carcinogen (glyphosate) make changes through inadvertent absorption through the food chain introduced solely for the profit of agribusiness is not a good idea.

So, to slightly expand upon my recommendations for soy: minimally processed non-GMO soy is a nutritious compliment to a diet, whereas processed soy proteins and GMO soy should probably be avoided whenever possible. Soy oils are likely safe, from a glyphosate point of view, but remember that oil is a processed food that should be used in extreme moderation, if at all.


2 replies on “Soy Epilogue: GMO Soy”

And avoid soy milk because of the same, right? It’s not GMO there hormones in it?

And you should do a post on food labels-what to look for, what makes something healthier than something else. Like…start with something basic everyone eats, like potato chips. Is there a worry about what they are being fried in? Are kettle chips better or worse?

Most of the soy milk available in the grocery store is GMO-free. Brands such as Silk, So!, and Blue Diamond are all certified GMO-free, so worries there. And, of course, there are no actual hormones in any soy product (unlike dairy milk, which is thick with estrogens as well as other nasties). So, no problems with soy milk if that’s the dairy free milk you prefer. Personally, I like almond milk, but that’s just my preference.

I will consider a food labeling post. For now, just now that if you’re choosing to eat chips that have been fried, you’re accepting that they will have a significantly higher level of processed oils. Some authors (Caldwell Esselstyn (Rip Esselsyn’s father), John McDougall, and Dean Ornish) would all advise you to limit oil consumption as much as possible (none if you can do it). While I agree that there are considerable health benefits to doing so, it isn’t entirely practical nor easy to do so.

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