Is Soy Really A Good Food?

"We have placed soy foods (such as soybeans) on our "10 Most Controversial WHFoods List." This list was created to let you know that even though some foods (like soybeans) can make an outstanding contribution to your meal plan, they are definitely not for everyone. Soy foods can be difficult to find in high-quality form; can be more commonly associated with adverse reactions than other foods; and can present more challenges to our food supply in terms of sustainability. More details about our 10 Most Controversial WHFoods can be found here.

What's New and Beneficial About Soybeans

• We recognize that soybean consumption is a matter of much current debate. There has been much written about it on the Internet, with claims that eating soybeans can endanger your health. To provide you with a comprehensive perspective on this topic, we have reviewed the research on soybeans. Throughout this food profile we have addressed the key controversial issues, focusing on them especially in our Health Benefits and Individual Concerns sections. Reading through this food profile you can explore our discovered insights into this traditional food, including how the research is quite different when it comes to whole soybeans versus isolated soybean derivatives and how fermented soybean foods may provide more benefits than unfermented ones. Read the full profile for more details.
• Researchers have recently asked a very simple question about soybeans: what would happen in terms of nutrition if U.S. citizens replaced their current intake of meat and dairy products with soy? Using previously collected information on the U.S. population and average U.S. dietary intake, these researchers determined that replacement of meat and dairy with soy would result in significantly improved intake of folate and vitamin K; larger amounts of calcium, magnesium and iron; and 4 additional grams of fiber per day. At the same time, replacement of all meat and dairy with soy would lower average cholesterol intake by 123 milligrams per day and lower average saturated fat intake by 2.4 grams per day. Protein would decrease somewhat (by approximately 8 grams per day, or 9% of average protein intake). Given the relatively high average daily intake of protein in the U.S. (which in some cases, is nearly double the Dietary Reference Intake level), this 9% decrease in total protein intake does not seem problematic to us—making this "soy substitution" seem like good nutritional trade-off. We're not advocating replacement of all meat and dairy foods with soy! High-quality meat and dairy foods can play a very supportive role in many diets. But alongside of the many controversies swirling around soybeans and health, we think it's important not to lose sight of the strong nutritional value of this legume.
• Soybeans have long been recognized as a plant food that, when compared with other plants, is relatively high in protein. Protein is the reason that soybeans have historically been called "meat of the field" or "meat without bones." But only recently have researchers taken a very close look at the protein content of soybeans and arrived at some fascinating conclusions. Even though soy protein is a plant protein and typically lower in certain amino acids (protein building blocks) than animal proteins like those found in chicken eggs or cow's milk, once adjustments have been made for digestibility and other metabolic factors, soybeans turn out to receive a protein quality rating that is equal to the ratings for egg or cow's milk. Along with this increasing interest in soy protein has come the discovery of very small and unique proteins in soy, typically referred to as "peptides." Examples of unique peptides in soybeans include defensins, glycinins, conglycinins and lunasin, and all are now known to provide us with health benefits, including benefits in the areas of improved blood pressure regulation, better control of blood sugar levels, and improved immune function.
• Because research studies have provided some mixed results about the impact of soy consumption on our cardiovascular system, researchers in the College of Medicine at the University of Kentucky recently analyzed results from 43 previously published studies involving on soy protein and risk of coronary heart disease (CHD). What they found was an overall decreased risk of CHD when approximately 30 grams of soy protein was consumed on a daily basis. Decreased LDL cholesterol was found to be an important part of this lowered risk. While we think it makes the most sense to consume soybeans in their whole food form (versus soy protein alone), and that daily protein intake should come from a variety of different foods, the findings in this study lend support to the conclusion that soy can play a beneficial role in support of cardiovascular health.
• When we think about antioxidant foods, the first foods that come to mind are usually vegetables. But recent research on soy has underscored many of the impressive antioxidant benefits that we get from this legume. No phytonutrient in soy has received more widespread attention than genistein—an isoflavone that has been extensively studied in relationship to cancer risk. Yet, genistein is a soy component that could easily be singled out for its antioxidant properties! Increased activity of antioxidant enzymes—including superoxide dismutase, glutathione peroxidase, catalase, and glutathione reductase—has now been linked to intake of genistein from soy. Another group of antioxidant phytonutrients called phenolic acids has also been recently investigated in soybeans. When we enjoy this antioxidant-rich legume, we also benefit from its phenolic acids, including caffeic, coumaric, ferulic, and sinapic acid.
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• So, is soy really a good food or have we messed this natural food up, too?  What do you think, HyMark readers?  What is the food quality of typical U.S. soybeans?
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• Ed Winkle