While the “Dos and Don’ts” of dietary guidelines always seem to fluctuate over the years, there is one food that has not only gained in popularity, but it is also consistently chosen as an alternative to milk. This humble legume is the soybean and has been long glorified as a great source of protein, especially for vegetarians. Yet, despite it’s fame amoung those who just want to eat less meat, there may be a downside to the consumption of this once much lauded food. In fact, according to Kaayla T. Daniel, PhD, CCN and author of The Whole Soy Story: The Darkside of America’s Favorite Health Food, there may be a significant downside to this favored ingredient despite all the nutritional data that has heretofore supported and encouraged the consumption of soy.
What is Soy?
The soybean is a legume that is an East Asia native, and while the bean is edible, it is poisonous to humans unless it is first cooked in a manner such as boiling, This destroys the dangerous trypsin inhibitors found within the bean. When properly prepared for consumption, it is true that soy beans are indeed a great source of protein, and more than that, they are considered to be a complete protein. This means that soybeans contain a significant amount of all nine essential amino acids which are required for our daily needs. Only an egg white contains higher amounts of these nine amino acids, therefore, for vegans especially, soy is often an integral source of dietary protein. Soy milk, tofu, tempeh, soy sauce, soy-based infant formula and other manifestations of soy, are all derived from the soybean plant.
The Good, The Bad
Soy has been accredited with lowering cholesterol, and because it lacks animal fats, it is also thought to reduce the occurrence of heart disease and even some cancers. Here, however, is where things get confusing, for with every study that shows how beneficial soy is, there are other studies showing how harmful it can be. Some studies link soy consumption with malnutrition, thyroid dysfunction, reproductive disorders, cancer, heart disease and other things we’d all like to avoid. So why all the conflicting studies?
Perhaps part of the answer lies in how soy is grown. In the United States, more than 90 percent of all soybean crops are genetically modified. They’re also doused with chemical herbicides, some of which may be carcinogenic. Even organically grown soybeans contain a variety of saponins, soyatoxins, phytates, trypsin inhibitors and a variety of other odd sounding components which are considered antinutrients which are components that are harmful to our bodies. The fermentation process traditionally employed to make soy sauce destroys these antinutrients, thereby allowing our bodies to reap the nutritional rewards of soy. However, unfermented soy such as tofu and soymilk does not undergo this process and is thereby filled with these nasty sounding antinutrients which can interfere with digestion, block the synthesis of hormones, and wreak general havoc on our body’s ability to process nutrients.
All Soy is Not Created Equal
As dangerous as many claim unfermented soy to be, the benefits of fermented soy products such as soy sauce, tempeh, miso and natto can be significant. Organic soybeans that are treated with a fermentation process can be a valuable source of vitamin K2, which, when combined with vitamin D, can be a powerful ally against dementia, cardiovascular disease and osteoporosis.
Some claim that Asians, who have a lower incidence of prostate and breast cancer compared to those of us in the United States, eat more soy products than we do, so how can it be harmful? The reality is, however, that Asian diets really only include a small amount (about 9 grams) of fermented soy compared to the ever popular processed soy products in the U.S. that can contain 20-grams or more of soy in one serving.
Soy is found in a myriad of products, from cereals to vitamins supplements, canned goods, chocolate, meats and more. It can be called different names, like hydrolyzed vegetable protein, and it is one of the foods most likely to cause allergic reactions. These reactions can range from severe to so mild that we don’t even notice them in our day to day activities.
What to Do?
The USDA suggests that American adults consume 0.80 grams of protein per kilogram of body weight [5]. For a 150 pound man or woman, that translates into about 54 grams of high quality protein every day. Twenty five grams of protein are in a typical 3-ounce serving of lean protein like white meat chicken, and one cup of cow’s milk contains 8 grams of protein. By comparison, 1 cup of cooked quinoa contains about 18 grams of protein.
The evidence is clear that a plant based diet, with adequate vegetable sources of protein, is far healthier for us, especially considering that most of us eat far more meat and dairy than we really need. Over-consumption of meat is well documented and leads to heart disease, cancers and many other unfavorable conditions. Perhaps the answer is in to limit the amount of soy that we consume, and, if we’re following a vegetarian diet, to look for protein in other legumes, quinoa, nuts, seeds and more importantly, fermented soy products like tempeh.
The next time you’re craving a healthy and nutritious snack, skip the bowl of tempting edamame and opt instead for a handful of nuts, or, better yet, learn to love tempeh which is in itself, a powerful superfood.
Resources
[3] http://www.mercola.com/Downloads/bonus/dangers-of-soy/report.aspx
[5] http://www.cnpp.usda.gov/Publications/DietaryGuidelines/2010/DGAC/Report/D-4-Protein.pdf
