Walk down an aisle of almost any grocery store these days, and you will surely be met with numerous products containing soy or soy derivatives. Soy has made it’s way into hundreds of thousands of food and industrial products in the past few decades. Besides corn, I would be hard pressed to think of another crop that has been used to make such a range of products as tofu, ice cream, cupcake liners, tea bags, and glue for cardboard boxes. It’s positively everywhere, and so is the controversy that follows it.
Conflicting literature and scientific data leaves most of us just plain confused and annoyed. We ask ourselves, Should I stop drinking soy milk? Is tofu a healthy meat alternative? What about soy protein powder? Believe me, I have asked those same questions and have a hard time knowing who to believe. Crooked food industry politics and flawed studies aside, there are some important take-home messages regarding soy that you as a consumer and health activist should know.
Soy: good or bad?
First, the facts. Soy is a member of the legume family and is a very versatile plant. Soybeans are relatively higher in protein than other legumes, and also contain all the essential amino acids, which is why soy proponents consider it to be the only vegetable-based “complete” protein. As a whole food, soybeans are high in fiber and healthy fats (lecithin and essential fatty acids omega 6 and 3). Soybeans contain a variety of vitamins and minerals, such as molybdenum, manganese, iron, phosphorous, and vitamin K.
For thousands of years, soy has traditionally been used in Asian cultures in the form of fermented soy products such as miso, natto, and tempeh. In the U.S., on the other hand, we see it take many different shapes. Americans consume soy mostly in the form of tofu, soy milk, and a host of meatless products, such as soy sausages, soy burgers, vegan cheese, textured soy protein, and protein powders. Soy is also one of the food industry’s favorite products to manipulate because it adds fat and protein, which means derivatives of soy are often the second or third ingredient (behind sugar) in junk food. Soy is also cultivated largely for its oil and for the purpose of animal feed.
According to Soyatech, “about 85% of the world’s soybean crop is processed into meal and vegetable oil, and virtually all of that meal is used in animal feed. Approximately 6% of soybeans are used directly as human food, mostly in Asia.”
In the 80s and 90s, soy was thrust into mainstream and began being touted as the up-and-coming health food that would stop malnutrition, cure cancer and prevent heart disease. We’ve seen its precarious reputation grow more recently as it becomes clear that many of these original health claims are founded on weak scientific data, or none at all.
Let’s address the confusion
-Most soy you consume is heavily processed in the form of meat substitutes or soy oil. The processing methods used to make these products involve extremely high heat and pressure which denatures the protein (i.e. destroys the fragile molecular bonds, making it hard to digest) and creates carcinogens. Remember when I said it’s considered a “complete” protein? Well, it has been shown that this processing damages the balance of amino acids, especially the sulfur-containing methionine, making soy protein much less bioavailable than animal protein and therefore not entirely a complete protein.
– Soybeans are the least digestible of legumes. It is an enzyme inhibitor, which means its protein is harder to digest, and that can cause gastric distress and deficiencies in amino acid uptake. Soy is also high in mineral-blocking phytic acid. This explains why miso and tempeh are proclaimed to be such healthy foods- fermentation deactivates these harmful qualities in soy.
– Soy contains phytoestrogens, which are a naturally occurring plant compounds that have a similar molecular structure to the hormone estrogen. Research has demonstrated that too much soy can create a hormone imbalance and possibly disrupt the endocrine system, which has been associated with reproductive cancers. BUT- there is not concrete evidence that soy consumption increases breast cancer rates, and some studies have even shown that soy may even be protective against prostate cancer.
– Soy contains isoflavones, which are thyroid- depressing compounds: people suffering from hypothyroidism should stay away from soy because it could increase their symptoms, such as fatigue and issues with metabolism.
So what should I DO?
The food and agricultural industry has done an excellent job convincing us that soy should be an essential part of our daily diet. Nevertheless, determining the honest health benefits or health problems associated with soy consumption can be a frustrating and confusing task, in part because of the heavy marketing, but also because the research offers conflicting information. Here’s my soy advice:
-Don’t use soy as your main source of protein.
-Stay away from processed soy products (junk food).
-Check labels for added soy ingredients. These are the words soy isoflavones, soy protein, soya flour, soy lecithin, and textured soy protein, for example.
-Look for organic soy products (the only way to get non-GMO) and soybeans not from China (often has food safety issues).
-It may not be necessary to completely eliminate soy products from your diet, but if you do choose to eat it, try to get a variety of different soy products in moderation and make sure of them are “old-fashioned” (i.e. fermented products).
AHA article about soy and AHA’s position on soy
The Whole Soy Story
More info about soy and phytoestrogens
Summer Tomato’s webinar on soy
Soy and thyroid health
Soy and breast cancer
Soy and prostate cancer
The Whole Soy Story, by Kaayla Daniel