Soya Beans

Soybean is hailed as the most protective bean. Soy contains 40 percent protein. It has the highest protein content amongst plant products. “Soy protein” refers to the protein found in soybeans. As animal protein contains all the essential amino acids, lacking in pulse protein, soy is often used to replace the animal proteins in an individual's diet. Soybean is the only vegetable food that contains all eight essential amino acids. Soyabeans are processed to various soya products namely soy flour, soy milk, cottage cheese like tofu, fermented products like tempeh and miso.

Macronutrients-
Protein
Soyabean is the richest plant source of protein. It contains 43 percent protein as compared to other legumes which contain 20 to 25 percent protein. Soy protein is also of the highest quality amongst all legumes. Under guidelines adopted by the Food and Drug Administration and the World Health Organization for evaluating protein quality for children and adults, soy protein isolate receives a rating of 1, which is the highest possible score. This means that the quality of soy protein is equal to that of meat and milk proteins.

Most plant proteins are considered "incomplete" proteins because they are low in one or more essential amino acids. Levels of one amino acid or another are insufficient for human needs. Grains are typically low in lysine; beans are typically low in the sulfur amino acids, methionine and cysteine. However, the level of sulfur amino acids in soybeans is higher than in other beans, and therefore soy protein is equivalent to animal protein in quality. 

The World Health Organization (WHO) and the US Food and Drug Administration use an alternative method for evaluating protein quality called the protein digestibility corrected amino acid score (PDCAAS). The PDCAAS for soy protein isolate is 1.0, which makes soy equivalent to animal proteins in quality and higher than other plant proteins foods. Soy foods if used smartly contribute significantly toward meeting protein needs, and could be an excellent addition to a diet for a variety of reasons.

Fat

Like protein soybeans are high in fat too. Most legumes (except peanuts) contain between 2 to 14 percent fat, whereas soybean contains 19 percent fat. 

At the same time, most of the fat in soybeans is unsaturated and beneficial. Polyunsaturated, monounsaturated and saturated fats make up 63 percent, 23 percent, and 14 percent respectively of the fat in soybeans with saturated fat being the lowest. The polyunsaturated fat content of soybean includes linolenic acid or Omega-3 fatty acid. The presence of omega–3 fats makes it special as soybeans are one of the very few plant sources of this essential fatty acid. Omega-3 fatty acids form an essential nutrient which helps to reduce risk of both heart disease and cancer. 

Soybean oil can be used in cooking. Some soy foods have the fat removed. Defatted soy flour is commonly available. Reduced-fat tofu and reduced or non-fat soymilk also form some low fat alternatives.

Fiber

A serving of soybeans provides approximately eight grams of dietary fiber. However, some soy foods are processed in ways that decrease the fiber content significantly. Tofu and soymilk contain very little fiber, while soy foods that utilize the whole bean such as tempeh, soy flour and textured soy protein are high in fiber. 

Micronutrients-

Calcium

Soy foods are a good source of calcium in comparison to the commonly used legumes. Processing affects the calcium content of soyfoods considerably. Tofu due to its processing methods can contain between 120 and 750 mg of calcium per 1/2 cup serving. Soymilk contains around 93 mg of calcium per one cup serving. The calcium-fortified soymilk could often contain between 200 and 300 mg of calcium per serving and a good amount of vitamin D.

Although soyfoods are high in both oxalates and phytates that inhibit calcium absorption, the calcium from soyfoods is well absorbed and has an absorption rate equal to that of milk.

Iron

Soya is rich in iron too. However, both phytate and soy protein reduce iron absorption which leads to the iron in soyfoods being poorly absorbed. Iron could be better absorbed from fermented soyfoods like tempeh and miso.

Other nutrients-

Like other whole grains, soyfoods are rich in B-vitamins, particularly niacin, pyridoxine and folacin. Soymilk is well fortified with vitamin B12 which makes it a prominent source of this essential nutrient.

History

Soybeans have been cultivated in China for thousands of years, and they also became popular in other Asian countries (especially Japan and Korea) over a thousand years ago (as early as the third and fourth centuries AD). Thanks to their origins in Asia, we continue to use three Japanese words - "tofu" (itself from the Chinese word "doufu"), "natto," and "edamame" (meaning "branch bean" or "stalk bean") to refer to various forms of this wonderful legume.

Many countries in the world depend on soybeans and other legumes as key sources of dietary protein. However, for the past 30-35 years, soybeans have seldom been produced in the United States for the purpose of being consumed in whole food form by humans. Instead, a $20 billion industry has grown up around the cultivation of soybeans as an "oilseed" crop that can be traded alongside of other interchangeable commodities like rapeseed, sunflowerseed, and cottonseed. Even though the United States has become the world's larger grower of soybeans (producing approximately 83 million metric tons of soybeans on 75 million acres of land), these soybeans are not being cultivated for human food use but for other purposes (their extractable oil and their processing into animal feed). This historical trend has given rise to a whole new classification of soybeans as an "oilseed crop" or "oilseed commodity." When economists talk about soybeans that are intended to be consumed in whole food form by humans, they use the terms "vegetable soybeans" or "garden soybeans" or "edible soybeans" to describe this food.

This new interest in soybeans as an oilseed crop has also been accompanied by widespread genetic engineering of the legume. Nearly 90% of all soy products in the U.S. marketplace now come from soybeans that have been genetically engineered (GE), making them one of the world's top foods in terms of genetic modification. Genetic engineering of soybeans began as early as 1998 with the introduction of soybeans into the marketplace that had been modified for better resistance to the commercial herbicide glufosinate ammonium. Since 1998, at least eight other GE patents have been granted for use on soybeans, most of them involving better resistance to pesticides and herbicides. If you are trying to avoid consumption of GE soy in your diet, your best bet is to purchase certified organic soybeans and soy products, since genetic engineering is not allowed under federal organic regulations.

How to Select and Store

Dried soybeans are generally available in pre-packaged containers as well as bulk bins. Just as with any other food that you may purchase in the bulk section, make sure that the bins containing the soybeans are covered and that the store has a good product turnover so as to ensure its maximal freshness. Whether purchasing soybeans in bulk or in a packaged container, make sure that there is no evidence of moisture or insect damage, and that the beans are whole and not cracked.

Canned soybeans (dried beans that have been cooked for you by the manufacturer) can be found in many markets. Unlike canned vegetables, which can lose much of their nutritional value, there is typically less loss of nutrient richness with the canning of soybeans. Canning lowers vegetables' nutritional value since they are best lightly cooked for a short period of time, while their canning process often requires a longer cooking time and/or higher cooking temperatures. By contrast, dried beans require a longer cooking time whether they are cooked by the manufacturer and then canned for your convenience, or whether you purchase them in dry form and cook at home yourself. Therefore, if enjoying canned beans is more convenient for you, by all means go ahead and enjoy them. We would suggest looking for those that do not contain extra salt or additives. (One concern about canned foods is the potential for the can to include a liner made from bisphenol A (BPA). To learn more about reducing your exposure to this compound, please read our write-up on the subject).

Of course, another alternative for soybeans is to purchase them in their fresh green form before they have been dried. Edamame (fresh green soybeans that may be raw or may already have been boiled or steamed either individually or in the pod) should be deep green in color and if purchased in the pod should come from pods that are firm and unbruised. Edamame can be found in many supermarkets as well as in natural foods stores and Asian markets. It is usually available in the frozen food section, although during its peak season you can find it the produce aisle of many natural food stores and Asian markets.

Remember to stick with the whole food forms of soy, and also consider giving preference to fermented versions like tempeh, fermented tofu, and soy miso.

Store dried soybeans in an airtight container in a cool, dry and dark place where they will keep for up to 12 months. If you purchase soybeans at different times, store them separately since they may feature varying stages of dryness and therefore will require different cooking times. Cooked soybeans will keep fresh in the refrigerator for about three days if placed in a covered container.

Fresh edamame should be stored in the refrigerator and eaten within two days. Frozen edamame will keep fresh for a few months.

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.

WHFoods Recommendation

When including soybeans, try to stick with the whole food forms, and also consider giving preference to fermented versions like tempeh, fermented tofu, and soy miso.

Unfortunately, in the United States, we seldom consume soybeans in their whole natural form (either fresh or dried). Instead, we process soybeans by using hexane or other solvents to remove the oil (which can be sold as cooking oil or oil to be added to other processed foods), and then we take what's left over (defatted soy flour) and either (1) combine it with other proteins to make animal feed or (2) wash it with water to create soy protein concentrate. Soy protein concentrate becomes the source for two forms of soy that are even more processed: TVP, or textured soy protein that can be produced through a process called extrusion, and SPI (soy protein isolate), which can be produced by making the soy protein concentrate more solubilized. SPI is used in many low-fat soy milks.

All of the above processing steps create a soy product that is very different from the soybeans' whole food form. A full-fat soy milk, for example, can be made by simply cooking whole soybeans in water and using a cloth to strain the soymilk (liquid) from the fibrous part of the cooked beans. Tofu can be made from full-fat soy milk by using salts or acids to coagulate the milk into curds that can be pressed into "cakes." (Tofu can be further preserved through fermentation.) Natto is another good example of a whole food form of soybean. Natto can be made by taking whole soybeans, adding a bacteria called Bacillus subtilis, and giving the bacteria time to ferment the beans. Natto, tofu, and full-fat soymilk are whole food forms of soybean that stand in sharp contrast to processed forms like TVP and SPI.

Since genetically modified (GM) soybeans have reached 90% market penetration in the United States select organically grown soy products to avoid GMO.

Public Health Recommendations

Many public health organizations—including the American Diabetes Association, the American Heart Association, and the American Cancer Society—recommend legumes (the category in which soybeans are classified) as a key food group for preventing disease and optimizing health. The 2005 Dietary Guidelines for Americans developed by the U.S. Department of Health and Human Services (USDHHS) and the U.S. Department of Agriculture (USDA) recommends 3 cups of legumes per week (based on a daily intake of approximately 2,000 calories). Because 1 serving of legumes was defined as 1/2 cup cooked, the Dietary Guidelines for Americans come very close to this as they recommend of 1/2 cup of cooked legumes on a daily basis. Based on our own research review, we believe that 3 cups of legumes per week is a very reasonable goal for support of good health. However, we also believe that optimal health benefits from legumes may require consumption of legumes in greater amounts. This recommendation for greater amounts is based upon studies in which legumes have been consumed at least 4 days per week and in amounts falling into a 1-2 cup range per day. These studies suggest a higher optimal health benefit level than the 2005 Dietary Guidelines: instead of 3 cups of weekly legumes, 4-8 cups would become the goal range. Remember that any amount of legumes is going to make a helpful addition to your diet. And whatever weekly level of legumes you decide to target, we recommend inclusion of soybeans among your legume choices. 

The Soy Controversy

Given the fact that soybeans are a food that has been enjoyed by millions of people over thousands of year, it's unexpected to find so much controversy surrounding this legume. And yet in the public press and in scientific research, soybeans have been a topic of ongoing controversy. For example, in 1999, the U.S. Food and Drug Administration (FDA) authorized a health claim for soy protein as a nutrient that could reduce risk of heart disease. And yet in 2007, numerous scientists in the U.S. officially asked the FDA to revoke its heart-related health claim for soy protein.

We suspect that one basic factor accounts for most of the controversy that has surrounded soy and its role in a healthy diet. This factor is what we would summarize as "east versus west." Soybeans were adopted as important parts of the diet in China (and then later in Japan and Korea) long before they became part of European or North American diets. Culinary traditions involving soy have existed for dozens of generations across Asia, but remain almost non-existent even today in Western countries like the United States. When research is conducted on the health benefits of soybean in Asian diets, the findings seldom match up with research findings on U.S. and European populations.

What makes Eastern countries and Western countries so different with respect to soy? The answer to this question is complicated, but three issues seem especially important.

Soybeans are typically consumed as whole foods in the East

First and perhaps foremost is the approach to soybeans as a dietary component in Eastern versus Western countries. In Eastern countries like China, Japan, and Korea, soybeans are typically consumed as whole foods. They may be cooked, roasted, fermented, or sprouted, but they are allowed to remain intact in the diet. Soybean consumption in Asia almost always involves a form of the legume that is whole food-related. In sharp contrast, consumption of soy in the United States seldom involves a whole food form. In the U.S., most of the soybean we consume has been highly processed, following cracking, dehulling, crushing, or being subjected to solvent extraction processes to separate the oils from the rest of the bean.

Total soy consumption is different when comparing East to West

The amount of total soybean consumption in Eastern versus Western countries is also very different. In studies from China and Japan, it's not surprising to see intake of soybeans occurring at the level of 100-200 grams per day. Yet in the U.S., we average less than one-tenth of that amount.

Metabolic differences

Longstanding culinary traditions involving soy also seem to have contributed in various ways to important metabolic differences in Asian versus non-Asian populations. For example, about 50-60% of adults in Japan, China and Korea digest soybeans in such a way as to convert daidzein (one of soy's key isoflavone phytonutrients) into equol (a closely-related phytonutrient called an isoflavan). By contrast, when U.S. adults eat soybeans, only 25-30% metabolize daidzein in this way. The role of bacteria in the digestive tract seems critical in the equol production process, and there may be other aspects of metabolism that also play pivotal roles.

When combined, these metabolic and whole-versus-processed food differences make research on soy difficult to interpret. A soy-related dietary practice that works for adults in China may not work for adults in the U.S., or vice-versa. In addition, until soybeans are enjoyed on a more regular basis in their whole food form in the U.S., research studies on U.S. adults may continue to show mixed results in terms of health benefits.

Even with all of the "east versus west" circumstances that complicate research on soybeans and health, we believe several areas of health benefit still shine through in studies of this much-loved legume. In the paragraphs below, you will learn more about these specific health areas.

Overall Nutrient Benefits

According to a recent research analysis, U.S. adults would increase their intake of folate, vitamin K, calcium, magnesium, iron and fiber if they replaced their meat and dairy intake with soy. Since legumes like soybeans are often overshadowed by vegetables and fruits in terms of nutrient richness, we sometimes forget just how beneficial legumes like soybeans can be.

Along with the nutrients listed above, soybeans are also an important source of the minerals copper, manganese, molybdenum, phosphorus, and potassium; the B vitamin, riboflavin; and omega-3 fatty acids (in the form of alpha-linolenic acid). Replacing meat and dairy with soy would also lower total cholesterol intake by about 125 milligrams per day and saturated fat by about 2.4 grams per day. These nutritional changes, in turn, would lower risk of several chronic diseases, including cardiovascular diseases. The idea of getting 10 grams of fiber and 25-30 grams of high-quality protein for 300 calories (1 cup of soybeans) is somewhat amazing. On a diet of 1,800 calories, 300 calories would only represent 16-17% of the total calories for one day. Yet, while only taking up one-sixth of the day's calories, a cup of soybeans provides us with 40% of the Daily Value for fiber and 50-60% of the Daily Value for protein!

In addition to all of their nutrient richness described above, soybeans also offer many unique nutrients less familiar to most people. In some cases, the health benefits of these nutrients are only beginning to be understood by researchers. Below is a list of some key nutrients currently under investigation in soybeans.

• Flavonoids and Isoflavonoids
• daidzein
• genistein
• malonylgenistin
• malonyldaidzin
• Phenolic Acids
• Caffeic acid
• Coumaric acid
• Ferulic acid
• Gallic acid
• Sinapic acid
• Phytoalexins
• glyceollin I
• glyceollin II
• glyceollin III
• Phytosterols
• beta-sitosterol
• beta-stigmasterol
• campestrol
• Proteins and Peptides
• defensins
• glycinin
• conglycinin
• lunacin
• Saponins
• soyasaponins (group A and group B)
• soyasapogenols

Cardiovascular Benefits

As discussed earlier, research on soybeans has provided mixed results in the area of cardiovascular benefits, with some studies showing no benefits and other studies showing significant ones. We believe that two aspects of the "east versus west" phenomenon described earlier may have contributed to these mixed findings. First is the difference between studies involving whole soybeans versus studies involving processed soybean components (like soy protein isolates). In repeated research findings, whole food soybeans have been shown to provide us with better cardiovascular support than dietary supplements containing soy components. "Better" in this case means not only more consistent but also more in-depth cardiovascular support.

However, even in the case of whole food soybeans, we would not describe this cardiovascular support as being "strong." A better word would be "moderate." The most consistent effect of soybean intake on blood fats has been a moderate lowering of LDL cholesterol. Some studies show other positive impacts on blood fats, such as the lowering of triglycerides and total cholesterol or the raising of HDL cholesterol (the "good" cholesterol). However, these additional blood fat results have not been confirmed in all studies.

Soyasaponins are soy phytonutrients that have been especially interesting to researchers with respect to their cardiovascular benefits. There is some evidence, mostly in animal studies, that soyasaponins can lessen the rate of lipid peroxidation in blood vessels, lessen absorption of cholesterol from the GI tract, and increase excretion of fecal bile acids. All of these events would be expected to contribute to a decreased risk of cardiovascular disease. We look forward to further studies involving humans who take in soyasaponins through a normal diet that includes whole food soybeans.

Cancer Prevention Benefits

The area of cancer prevention is perhaps the most controversial area of health research on soybeans. Many studies provide us with evidence that supports the role of whole soy foods in a cancer-preventing diet. Genistein (an isoflavone phytonutrient in soy) is often a key focus in these cancer-prevention studies. This soy isoflavone can increase activity of a tumor suppressor protein called p53. When p53 becomes more active, it can help trigger programmed cell death (apoptosis) in cancer cells, and it also help trigger cell cycle arrest (helping stop ongoing cancer cell activity). Genistein has also been shown to block the activity of protein kinases in a way that can help slow tumor formation, especially in the case of breast and prostate cancer. It's also worth noting here that genistein becomes more concentrated in soy foods when those foods are fermented.

All of the above cancer-preventing possibilities of genistein and soy are complicated by other real-life factors, however. In some studies, the amount of genistein required to trigger cancer-preventive effects has been relatively high, and far higher than the amount provided by average intake among U.S. adults. The lifecycle and metabolic status of individuals also seems to make a potentially important difference in the anticancer benefits of soy. For example, in studies on soy intake and breast cancer, women who are pre-menopausal and develop tumors that are neither estrogen receptor nor progesterone receptor positive, soy and genistein intake do not appear to offer risk reduction. Overall dietary intake may also make an important difference in the anticancer benefits of soy. For example, without strong dietary intake of fresh fruits and vegetables, soy foods many not provide a reliable level of anticancer benefits.

In addition to the precautions about anticancer benefits of soy described above, there is also some evidence that large amounts of processed soy components (like might be obtained from large doses of purified soy isoflavones through dietary supplements) may actually increase risk of certain cancers, including breast cancer. This evidence should not be surprising. Under certain metabolic circumstances, most antioxidant, anti-inflammatory, and anti-tumor compounds can also act in a way that is pro-oxidant, pro-inflammatory, and pro-tumor (often called a "proliferative" affect that is promoting of tumor growth). It's certainly easy to see why soy has remained so controversial in the minds of some researchers!

Our recommendations to you based on all of this information are as follows: first, if you have a family history of hormone-related cancers like breast cancer or prostate cancer, we recommend that you consult with your healthcare provider before consuming very large amounts of soy in your diet (for example, 3 or more servings per day). This recommendation is a conservative one on our part, but we believe that it's justified based on the current level of controversy in the health research. Second, we recommend that you choose whole food soybeans whenever possible, rather than highly processed versions like soy protein isolates and soy protein concentrates. Finally, we recommend that you consider fermented versions of soy (including tempeh, fermented tofu, and miso) which have a better research track record in the cancer prevention area than non-fermented soy products.

In the overall picture, we continue to believe that soy foods can provide you with important health benefits, including anti-cancer benefits. But we also believe that persons wanting to include soy in an anti-cancer diet need to pay attention to the form of the soy, the amount consumed, their personal health history, and in some cases, the advice of their healthcare provider.

Soy and Hot Flashes

Hot flashes are very common symptoms of menopause and peri-menopause in U.S. women (often called "night sweats" when they occur at night) can cause great suffering and can easily affect mood throughout the day and impair concentration. Approximately 70-80% of U.S. women of menopausal and peri-menopausal age experience hot flashes, in comparison with approximately 10-20% of Asian women. By comparison, the average level of the soy isoflavone genistein in the bloodstream of Asian women is approximately 25 nanograms per milliliter, but in U.S. women, only 2 nanograms. This sharp contrast between frequency of hot flash symptoms and soy genistein levels has led many researchers to wonder about the hot flash-preventing potential of soybeans. Unfortunately, most studies to date fail to establish a reliable connection between dietary soy intake and occurrence of hot flashes. It's possible that future research studies will tell a different story, but at present, we aren't aware of any findings that show clear benefits for hot flash relief from increased intake of soy.

Bone Health Benefits

The area of bone health benefits from soy has remained nearly as controversial as the anti-cancer area due to the large amount of mixed evidence found in human studies on soy and bone health. In support of bone benefits has been the finding in many studies of improved markers of bone health following consumption of soy. (Improved bone health markers have included a decrease in the number of cross-linked telopeptides and a decrease in blood levels of bone specific alkaline phosphatase.) In addition, a lower rate of osteoporosis in some countries has been associated with increased intake of whole soy foods, especially fermented whole soybean foods. At the same time, however, soy intake (especially processed soy intake, including soy protein concentrates, isolated soy protein, and supplements containing purified soy isoflavones) has often failed to show any improvement in bone mineral density or bone metabolism.

Some of the mixed findings appear to be related to conversion of the soy isoflavone, daidzein, by intestinal bacteria into a metabolite called equol. In some Asian countries, the rate of equol formation in adults is approximately double the rate of U.S. adults. (Interestingly, among U.S. adults, the rate of equol formation from daidzein is almost double in vegetarians versus non-vegetarians.) Soy foods appear to be more helpful in supporting bone (for example, in lessening loss of minerals from bone) when individual metabolism and gut micro-organisms support the conversion of daidzein into equol. There is also some evidence that this entire process may be under some level of genetic regulation.

In the overall picture, we continue to believe that soy foods can provide you with important health benefits, including bone-related benefits. It's important to remember that soybeans provide a good amount of vitamin K—a much-needed nutrient with respect to bone health. (Soy foods fermented with Bacillus bacteria may be able to provide additional vitamin K benefits, as described later on in this Health Benefits section.) Equally important, soy protein is a plant protein. In broad studies of diet and bone health, plant proteins have a better track record in support of bone than animal proteins. Even though many controversies remain in the area of soybeans and bone health, we believe that your 4-8 cups of legumes each week (our World's Healthiest Foods recommended intake level for legumes) should contain some whole food form of soybeans—and especially versions that have also been fermented.

Soybeans and Obesity

Increased protein intake has always been associated with suppression of appetite, and plant foods like soy that provide concentrated amounts of protein have a research-based ability to help suppress appetite. (Of course, our experience of appetite is very complicated, and there is no simple way to change our appetite exclusively through diet.) Some studies on unique peptides (protein-like components) in soy have shown the ability of this peptides to decrease synthesis of SREBPs (sterol regulatory element binding proteins), thereby helping decrease synthesis of certain fatty acids as well as depositing of these fatty acids in fat cells. This fascinating research on soyfoods and obesity is still in the early stages, however.

Soybeans and Type 2 Diabetes

A second area of potential health benefit is prevention of type 2 diabetes. In multiple animal studies, soy foods have been shown to lessen insulin resistance by increasing the synthesis of insulin receptors. However, this increased formation of insulin receptors only appears to occur in the presence of other dietary circumstances, like a moderate amount of polyunsaturated fat intake. High levels of total soy intake (approximately 200 grams per day) have also been associated with decreased risk of type 2 diabetes, but only in Asian populations thus far. We look forward to more research on human consumption of soy and prevention of chronic health problems related to insulin metabolism and blood sugar levels.

Soybeans and Vitamin K

Soybeans of all kinds qualify as a good source of vitamin K based on our food-nutrient ranking system. However, your vitamin K benefits from soybeans may be increased in the case of certain fermented soy foods. By far the most famous micro-organism used in fermentation of soybeans is the koji mold, Aspergillus oryzae. (Aspergillus oryzae can also be called a fungus, since molds are simply a special type of fungus called filamentous fungus.) Koji mold is a key to many of the unique qualities of many soy pastes, as well as soy miso and soy sauce. However, other micro-organisms may also be used to help ferment soybeans, and one is the bacterium Bacillus subtilis. The use ofBacillus subtilis in soybean fermentation is especially important in production of the fermented soy food, natto (and (Bacillus subtilis var. natto is one special variant (strain) of Bacillus used in natto production.) Natto is a sticky and stringy form of soybeans in which you can still see the individual beans. It has a distinctly pungent aroma, and it has been widely enjoyed in Asia cuisines for several thousand years, and especially in Japanese cuisine. However,Bacillus bacteria are also sometimes used in the production of other fermented soy foods, including soy pastes (especially Chinese soy pastes) and soy miso. Korean-style soy sauce may also be fermented with the help ofBacillus bacteria.

From a health standpoint, one of the reasons that Bacillus bacteria are so interesting is their ability to create a form of vitamin K called menaquinone-7 (MK-7). Vitamin K (in all forms) is an important nutrient for bone health. Sufficient intake of vitamin K is associated with decreased risk of osteoporosis, since this vitamin is involved with maintenance of bone mineral density and also with shaping of bone structure (through gamma-carboxylation). In the case of MK-7 (the form of vitamin K produced by Bacillus bacteria, and a member of the vitamin K2 menaquinone family), we know that higher levels of MK-7 in the blood correspond to lower risk of hip fracture in older Japanese women, and that higher MK-7 levels correspond to increased intake of soy foods that have been fermented with Bacillus bacteria. One fascinating aspect of Bacillus-fermented soy foods is the potential ability of these bacteria to stay alive in our lower intestine after these foods are consumed. We've seen one study in which 1.6-20 million Bacillus bacteria (per gram of feces) were found to remain alive up to 6 days following consumption of natto. If Bacillus bacteria from fermented soy foods can remain alive in our digestive tract, they may keep providing us with vitamin K benefits many days after their consumption.

Another interesting piece of information about vitamin K and fermented soy foods involves regulation of health claims on food products in Japan. The Foods for Specified Health Uses, or FOSHU system does not currently allow for bone-related health claims for natto in the Japanese marketplace, even though this food is an approved FOSHU product recognized as containing MK-7. The reason for disallowed health claims is the lack of vitamin K deficiency in Japan, not lack of data to support a possible MK-7 benefit. (In other words, the Japanese population may already be taking good advantage of fermented soy foods and their potential vitamin K benefits!)

Other Areas of Potential Health Benefit

Other areas of active research on soy and health include chronic obstructive pulmonary disease (COPD), periodontal disease, and neurodegenerative disease.

Description

While not the most widely cultivated of all beans (that distinction goes to Phaseolus vulgaris, also know as the "common bean"), soybeans are a traditional part of diets in China, Japan and Korea and are currently grown in countries across the world including Brazil, Argentina, India, Paraguay, Canada, and the United States. At present, the United States plants and produces more soybeans than any other country in the world—approximately 83 million metric tons grown on 75 million acres of land. However, nearly 99% of all soybeans grown in the U.S. are processed for production of soil meal (to be used in animal feed) and soy oil. In countries where soybeans are consumed in whole food form rather than undergoing processing into meal and oil, these legumes often serve as an important and relatively inexpensive source of protein.

Like their fellow legumes, soybeans are actually seeds of a plant. In the case of soybeans, the plant is Glycine max. (The soybeans we find in the grocery store have already been removed from the pod and dried out.) We're accustomed to seeing dried soybeans in their light tan or pale yellow color, but mature dried soybeans can actually be found in a variety of different colors including black, brown, and blue. Fresh (undried) soybeans, however, are always green in color and when carefully cooked—either in the pod or after being removed from the pod—can turn an even richer and brighter shade of green. Although you will find some websites referring to green soybeans as "immature soybeans," that term isn't always accurate. Soybeans could be harvest at an immature stage, but many green soybeans available for purchase in the grocery store are mature when harvested—just not dried. Edamame (which means "stalk beans" or "branch beans" in Japanese) is a term that you will often see used to describe fresh green soybeans that may be available either individually or still inside the pod and may either be raw or already boiled or steamed. In all cases, the major difference is that edamame have not been dried. It's worth noting that in recent research studies, edamame have been shown to contain a similar level of isoflavonoids as cooked soybeans that were prepared from dry form.

Other whole food forms of soy include full fat soy milk, tofu, natto, and miso. Processed forms of soy such soybean oil, defatted soy flour and soy protein concentrates such as TVP (texturized soy protein and SPI (soy protein isolate) abound. We always recommend whole food forms of soy (for more detail on these different forms of soy see WHFoods Recommendations above).

Side effects of soya

Get protein from soy

Soy is a plant protein full of fiber, potassium, magnesium and other vitamins. Popular soy foods include tofu, edamame, miso and soy milk.

“Soy contains all the essential amino acids that play a role in supporting the body’s vital functions,” says Clare McKindley, clinical dietitian in MD Anderson’s Cancer Prevention Center. “It can be an easy way for people on a vegan or vegetarian diet and those with food allergies to get those required amino acids. But, as with any food, eating in moderation is recommended.”

A moderate amount of whole soy foods is up to three daily servings. Examples of a single serving include: 1 cup of soy milk, 1/2 cup cooked soy beans, 1/2 cup edamame or 1/3 cup tofu.

Soy and breast cancer

Because natural soy foods contain isoflavones, similar to estrogen, some people fear that soy may raise their risks for certain cancers. This is because estrogen is linked to hormonally-sensitive cancers, like breast cancer.

But according to the American Cancer Society, when it comes to soy, isoflavones may act like estrogen, but they have anti-estrogen properties as well. Some studies even show that people who ate soy were less likely to get breast cancer. 

“The current research does not support avoiding whole soy foods--even for cancer patients or survivors,” McKindley says.

Soy might lower the risk of other cancers

Soybeans, soy nuts and edamame all contain fiber. And, a diet high in fiber may lower your risks for several cancers, including colorectal cancer.

Studies among prostate cancer survivors indicate that eating soy foods may lower PSA levels. Among men in various stages of prostate cancer, those who consumed soy milk or isolated soy isoflavones saw their PSA levels rise at a slower rate. The effect was stronger in some men than others, making it unclear whether genetics or metabolism made a difference in lowering PSA levels.

A healthy balanced diet can include soy

It’s important to have a variety of foods in your diet, including soy.

“If you’re still uncomfortable adding whole soy foods to your diet yet want to reduce how much animal protein you eat, try these common alternatives: beans, lentils, nuts and seeds," McKindley says. "The protein (and amino acid) content will vary for each."

If you want to add soy to your diet, eat fewer processed soy foods, and choose more whole foods like edamame, tofu and soynuts. Does that mean you should skip the soy nuggets? Not necessarily. That’s a personal choice. But, remember that a processed soy nugget is just that—processed food. And, avoiding processed foods is another way to keep your cancer risks low.

If eating certain foods, like soy, gives you anxiety, skip them.

"Consider talking with a dietitian if you have questions about going meatless," McKindley says. "It's important to make sure you are getting all the nutrients your body needs. Talking with an expert will help you go in the right direction."

Allergic Reactions to Soybeans

Although allergic reactions can occur to virtually any food, research studies on food allergy consistently report more problems with some foods than with others. It's important to realize that the frequency of problems varies from country to country and can change significantly along with changes in the food supply or with other manufacturing practices. For example, in several part of the world, including Canada, Japan, and Israel, sesame seed allergy has risen to a level of major concern over the past 10 years.

In the United States, beginning in 2004 with the passage of the Food Allergen Labeling and Consumer Protection Act (FALCPA), food labels have been required to identify the presence of any major food allergens. Since 90% of food allergies in the U.S. have been associated with 8 food types as reported by the U.S. Centers for Disease Control, it is these 8 food types that are considered to be major food allergens in the U.S. and require identification on food labels. The 8 food types classified as major allergens are as follows: (1) wheat, (2) cow's milk, (3) hen's eggs, (4) fish, (5) crustacean shellfish (including shrimp, prawns, lobster and crab); (6) tree nuts (including cashews, almonds, walnuts, pecans, pistachios, Brazil nuts, hazelnuts and chestnuts); (7) peanuts; and (8) soy foods.

Some of the most common symptoms for food allergies include eczema, hives, skin rash, headache, runny nose, itchy eyes, wheezing, gastrointestinal disturbances, depression, hyperactivity and insomnia. Individuals who suspect food allergy to be an underlying factor in their health problems may want to avoid commonly allergenic foods.

Soy Food and Thyroid Health

Along with the increasing presence of soy foods in grocery stores and on restaurant menus has come increasing controversy over soybeans and thyroid health. We're not surprised to find strong conflicting opinions in this area because scientific research on thyroid and soy is both complicated and inconclusive. We have written an extensive review of what we know—and what we don't know—about this important issue at this point. You find the article Soy Food and Thyroid Health here.

Soybeans and Oxalates

Soybeans are among a small number of foods that contain measurable amounts of oxalates, naturally-occurring substances found in plants, animals, and human beings. When oxalates become too concentrated in body fluids, they can crystallize and cause health problems. For this reason, individuals with already existing and untreated kidney or gallbladder problems may want to avoid eating soybeans. Laboratory studies have shown that oxalates may also interfere with absorption of calcium from the body. Yet, in every peer-reviewed research study we've seen, the ability of oxalates to lower calcium absorption is relatively small and definitely does not outweigh the ability of oxalate-containing foods to contribute calcium to the meal plan. If your digestive tract is healthy, and you do a good job of chewing and relaxing while you enjoy your meals, you will get significant benefits—including absorption of calcium—from calcium-rich foods plant foods that also contain oxalic acid. Ordinarily, a healthcare practitioner would not discourage a person focused on ensuring that they are meeting their calcium requirements from eating these nutrient-rich foods because of their oxalate content.

Soybeans and Genetically Modified Organisms (GMOs)

Genetically modified (GM) soybeans have reached 90% market penetration in the United States, and if you are purchasing non-organic soy products, you are highly likely to be consuming soy that has come from a genetically modified plant. Since 1998, nearly a dozen patents have been approved for genetic modification of soybeans, mostly to increase their resistance to herbicides and pesticides that growers expect to spray on the plants during cultivation. If you are wanting to decrease your exposure to GM foods, choose organically grown soybeans (and foods such as tofu, tempeh and miso that have been made from organically grown soybeans), since the current USDA (U.S. Department of Agriculture) organic regulations prohibit any use of genetic modification. A wide assortment of processed foods contain soy-based ingredients (such as soy protein and hydrolyzed vegetable protein); you'll want to look for the organic version of these ingredients as well since most soy protein concentrates and hydrolyzed soy products have been made from GM soy.

Soybeans and Phytates

Phytates are substances found in soybeans (and many other foods) that can lessen the absorption of certain nutrients, especially minerals. Soy products in general (including products that are minimally processed) contain 1.4-3.0% phytates. Soy isolates (commonly used production of low-fat soy milk) usually contain a minimum of 2.89% phytates, and soy concentrates can contain up to 4.8-4.9% phytates. The message here seems clear: you're likely to get better nourishment from soy (especially mineral nourishment) if you consume it in whole food versus processed form.

Other Controversies

Some animal foods and some plants foods have been the subject of ongoing controversy that extends well beyond the scope of food, nutrient-richness, and personal health. This controversy often involves environmental issues, or issues related to the natural lifestyle of animals or to the native habitat for plants. Soybeans has been a topic of ongoing controversy in this regard.

Other Controversies

Some animal foods and some plants foods have been the subject of ongoing controversy that extends well beyond the scope of food, nutrient-richness, and personal health. This controversy often involves environmental issues, or issues related to the natural lifestyle of animals or to the native habitat for plants. Soybeans has been a topic of ongoing controversy in this regard.

Nutritional Profile

Soybeans are perhaps best known for their fantastic blend of protein and fiber. But soybeans are also an excellent source of molybdenum and copper. They are a very good source of manganese, phosphorus, and protein as well as a good source of iron, omega-3 fatty acids, dietary fiber, vitamin B2, magnesium, vitamin K, and potassium. There are also a wide range of unique proteins, peptides, and phytonutrients contained in soy. These nutrients include flavonoids and isoflavonoids (daidzein,genistein, malonylgenistin, and malonyldaidzin); phenolic acids (caffeic, coumaric, ferulic, gallic and sinapic acids); phytoalexins (glyceollin I, glyceollin II, and glyceollin III); phytosterols (beta-sitosterol, beta-stigmasterol, campestrol); unique proteins and peptides (defensins, glycinin, conglycinin, and lunacin); and saponins (soyasaponins from group A and group B, and soyasapogenols).

In-Depth Nutritional Profile

In addition to the nutrients highlighted in our ratings chart, an in-depth nutritional profile for Soybeans is also available. This profile includes information on a full array of nutrients, including carbohydrates, sugar, soluble and insoluble fiber, sodium, vitamins, minerals, fatty acids, amino acids and more.

Introduction to Food Rating System Chart

In order to better help you identify foods that feature a high concentration of nutrients for the calories they contain, we created a Food Rating System. This system allows us to highlight the foods that are especially rich in particular nutrients. The following chart shows the nutrients for which this food is either an excellent, very good, or good source (below the chart you will find a table that explains these qualifications). If a nutrient is not listed in the chart, it does not necessarily mean that the food doesn't contain it. It simply means that the nutrient is not provided in a sufficient amount or concentration to meet our rating criteria. (To view this food's in-depth nutritional profile that includes values for dozens of nutrients - not just the ones rated as excellent, very good, or good - please use the link below the chart.) To read this chart accurately, you'll need to glance up in the top left corner where you will find the name of the food and the serving size we used to calculate the food's nutrient composition. This serving size will tell you how much of the food you need to eat to obtain the amount of nutrients found in the chart. Now, returning to the chart itself, you can look next to the nutrient name in order to find the nutrient amount it offers, the percent Daily Value (DV%) that this amount represents, the nutrient density that we calculated for this food and nutrient, and the rating we established in our rating system. For most of our nutrient ratings, we adopted the government standards for food labeling that are found in the U.S. Food and Drug Administration's "Reference Values for Nutrition Labeling." 

Tips for Preparing and Cooking

Tips for Preparing Soybeans

Before washing dried soybeans, spread them out on a dark colored plate or cooking surface to check for and remove small stones, debris or damaged beans. After this process, place the beans in a strainer and rinse them thoroughly under cool running water.

To shorten their cooking time and make them easier to digest, dried soybeans should be presoaked. There are two basic methods for presoaking. For each, start by placing the beans in a saucepan and adding two to three cups of water per cup of beans.

The first method is to boil the beans for two minutes, take pan off the heat, cover and allow to stand for two hours. The alternative method is to simply soak the beans in water for eight hours or overnight, placing pan in the refrigerator so that the beans will not ferment. Before cooking the beans, regardless of method, drain the soaking liquid and rinse the beans with clean water.

The Healthiest Way of Cooking Soybeans

To cook soybeans, you can either cook them on the stovetop or use a pressure cooker. For the stovetop method, add three cups of fresh water or broth for each cup of dried beans. The liquid should be about one to two inches above the top of the beans. Bring the beans to a boil and then reduce to a simmer, partially covering the pot. If any foam develops, simply skim it off during the simmering process. Soybeans generally take about one to one and one-half hours to become tender using this method. They can also be cooked in a pressure cooker where they take about 40 minutes to prepare. Regardless of cooking method, do not add any seasonings that are salty or acidic until after the beans have been cooked since adding them earlier will make the beans more tough and will also increase the cooking time.

How to Enjoy

A Few Quick Serving Ideas

• Replace some of the wheat flour in your favorite baked goods recipe with soybean flour and increase the protein content of your cookies, cakes, muffins and breads.
• Mix sprouted soybeans into salads or use as toppings for sandwiches.
• Frozen edamame is simple to prepare and makes a great snack or appetizer. Just add the soybean pods to slightly salted water and boil for approximately 10 minutes.
• Add soybeans to vegetable stews and soups.

Soybean in comparison to other legumes is far superior in terms of health benefits.

 Low in fat with no cholesterol

 Contains essential heart friendly omega-3 fats

 An excellent source of fiber 

 Is a good source of enriched Calcium and Vitamin B12

 Is a complete protein, containing all the amino acids essential to human nutrition

 Provides important minerals such as calcium, magnesium, iron and selenium 

 Rich in probiotics in the form of fermented soy products, such as miso, tempeh, and soy yogurt

 Contains isoflavones which are beneficial in reducing risk of various cancers, heart disease and osteoporosis 

 Whole soy foods such as tofu and tempeh form a nutrient rich alternative to meat

Soybeans, cooked 1.00 cup 172.00 grams Calories: 298 GI: very low
Nutrient	Amount	DRI/DV (%)	Nutrient Density	World's Healthiest Foods Rating
molybdenum	129.00 mcg	286.7	17.3	excellent
copper	0.70 mg	77.8	4.7	excellent
manganese	1.42 mg	71.0	4.3	very good
phosphorus	421.40 mg	60.2	3.6	very good
protein	28.62 g	57.2	3.5	very good
iron	8.84 mg	49.1	3.0	good
omega-3 fats	1.03 g	42.9	2.6	good
fiber	10.32 g	41.3	2.5	good
vitamin B2	0.49 mg	37.7	2.3	good
magnesium	147.92 mg	37.0	2.2	good
vitamin K	33.02 mcg	36.7	2.2	good
potassium	885.80 mg	25.3	1.5	good

The Pros and Cons of Soy: More Study Needed

Soy milk, tofu and edamame are just a few of the many soy-rich foods touted for helping individuals reduce cholesterol levels and minimize risk of heart disease. But is soy just as beneficial for fighting cancer? 

A recent study indicates that it is, but the question of whether tofu and other soy-rich foods can combat tumor growth has yet to be definitively answered.

The effects of soy have been known to produce both positive and negative results in breast cancer patients, particularly because of the chemical makeup of isoflavones in soy. These isoflavones are similar to estrogen in structure. As they bind to estrogen receptors, they can either stimulate or inhibit estrogen-related tissue development, including breast tumors.

Too early to recommend soy-rich diet
A 2010 study indicated that women with estrogen-positive tumors had a 33% lower risk of recurring breast cancer when they ate higher amounts of soy (59 milligrams of isoflavones daily) compared to those who had the least amount (6.5 mg).

But Banu Arun, M.D., professor in MD Anderson's departments of Breast Medical Oncology and Clinical Cancer Prevention, notes that it might be too early to recommend to American breast cancer survivors an increase in soy-rich foods to reduce the risk of breast cancer recurrence. 

The reason? This particular study focused on women in China, where soy consumption is high. Their bodies are already used to its beneficial effects. Many Americans, on the other hand, have a minimal daily intake of soy (1 mg to 3 mg). 

"The effect of taking soy might be different in the Western patient population where they aren't eating as much soy," Arun says. 

Further study of soy and hormones needed
"This patient population was primed with soy and its good effects, so there may be a favorable milieu in their tissue. Furthermore, we also do not know if patients with certain subtypes of breast cancer might benefit from soy, whereas other patients with another breast cancer subtype might not benefit."

Further studies have yet to be conducted on the effects of isoflavones on a low-soy diet. Researchers speculate that there may be a connection between a high intake of soy and its possible enhancement of hormone-based cancer drugs. In the meantime, Arun isn't advising American breast cancer patients to completely avoid soy products, but rather to be moderate in intake. 

"I wouldn't say don't eat soy," Arun says. "Moderate consumption should be fine. I just wouldn't convert to a soy-rich diet to reduce breast cancer recurrence since we don't have the data yet for a Western population."