Revered for the numerous uses of its edible bean, soybeans, are the most widely grown and utilized legume in the world.
Soybeans originated in China where they were domesticated and cultivated into a food crop more than three thousand years ago. Soybeans were first introduced to Europe in the early 18th century. Around the same time, a sailor returning from China brought soybeans to the United States. Slow to catch on in America, soybeans were used primarily as livestock forage prior to the early 20th century.
In the early 1900s, famous American Chemist, George Washington Carver developed a variety of uses for the soybean. Perhaps one of the most influential was his suggestion that farmers rotate their crop with soybeans. The nitrogen fixing root nodules of soy replenished soil depleted by cotton harvesting and revolutionized farming practices. Within a few years, soy became a staple crop of the South and Midwest. Soybeans enjoyed such widespread success across the United States because of their ability to grow in a variety of soils and climates.
Like other beans, soybeans grow in pods featuring edible seeds. Soybeans are most frequently yellow, although beans come in a variety of colors including black, brown, blue, green, and mottled. The pods, stems and leaves are covered in fine brown or gray hairs. When soybeans mature they become hard and dry.
Today, 55% of world soybean production takes place in the United States. The majority of the US production is fed to animals or exported. Other leading producers include Brazil, India, China and Argentina.
Soybeans are perhaps best known for being the only complete, non-animal, protein source. What is not as well-known is that whole soy foods are a good source of fiber, B-vitamins and minerals.
A cup of edamame (immature, green soybeans) contains 254 calories and provides 22 grams of protein and 8 grams of fiber. A serving is an excellent source of vitamin C (15.3 mg or 51% of RDAs), thiamin (0.5 mg or 31%) and folate (200 mcg or 50%). Whole soybeans are also an excellent source of calcium, iron, magnesium, phosphorus, potassium and magnesium.
Although a serving of whole soybeans contains 12 grams of fat it is primarily from Omega-6 polyunsaturated fatty acids. Soybeans also contain a small amount of Omega-3 fatty acids. Like many other seed oils, a small amount of fat (about 10%) is saturated.
The average Japanese person eats 2 to 3 ounces (50 to 80 grams) of soy food daily in various forms (miso, tempeh and soy milk). In comparison, the average American eats about 5 grams a day but this is primarily in the form of oils, most often as partially-hydrogenated hidden in high-fat foods.
Soy protein has received attention due to its ability to influence cholesterol. Animal protein sources often raise cholesterol levels due to high saturated fat and cholesterol content. Soy protein has been proven to lower LDL (bad) cholesterol levels significantly. Studies have shown that soy protein not only lowers LDL cholesterol by up to 45%, it decreases total blood cholesterol and may even increase HDL (good) cholesterol levels.
Cholesterol lowering benefits are not the only heart health benefits of soy. Soy protein has been shown to reduce the stickiness of platelets, (possibly due to omega-3 fatty acids found in soybeans) and promote the production of prostacyclin. Prostacyclin is a natural inhibitor of platelet aggregation and a blood vessel wall dilator.
Soy contains the isoflavones genistein and daidzen. These phytonutrients, which have weak estrogenic activity in the human body, are credited with soy’s ability to lessen the symptoms of menopause in many women. Studies have also demonstrated that soy foods can inhibit bone loss and stimulate bone formation in menopausal women.
Because the isoflavone molecule is similar to the estradiol molecule, the major estrogen hormone in the human body, there is concern that consuming soy products could promote the growth of estrogen sensitive cancers. Although isoflavones do have the ability to react with estrogen receptors in our body, they are not the same as the body’s natural estrogen. However, women with hormone positive breast cancers should consult with their doctor before consuming soy foods and are advised against taking soy isoflavone supplements.
On a less controversial note, soy allergies are common and most often reported among young children. Soy proteins are far less potent at triggering allergy symptoms than allergens like peanuts and shell fish so symptoms and reactions are considerably less severe.
Selection and Storage
Dried soybeans and frozen edamame can be found in most major grocery stores year round. For fresh edamame, check your local Asian market. Fresh soybeans or edamame should be refrigerated and used within 2 days. Frozen edamame can be stored in the freezer for several months. Dried soybeans, stored in a cool, dark place can remain fresh for even longer.
To prepare dried soybeans for use in your favorite soups and stews soak the beans in water for about 8 hours. For every 1 cup of beans, use 3 cups of water. Soaking soybeans improves the texture and removes some of the indigestible sugars. After soaking the beans, drain, rinse and cook without salt. Salt used in the pressure cooker stage of cooking will delay the softening of the soybeans. Like other beans and legumes, you can skip the soaking step by purchasing canned soybeans that have already been cooked, reducing preparation time.
Whole soybeans can be used in a variety of recipes. For more information on how to use soyfoods like tofu, soy dairy alternatives, soynut butter and soy meat alternatives refer Top 10 Soyfoods for Health.
Edamame, a popular Japanese dish made with immature soybeans that have not yet hardened, is the simplest way to enjoy soybeans. Edamame is frequently cooked in salt water. To keep sodium intake minimal, cook with just a dash of salt. Unsalted, a half cup of soybeans contains only 25 mg of sodium. If you have edamame left over, toss the beans into a salad to boost the nutritional content.
For a delicious dip or spread described by tasters as “fresh and zingy” try your hand at Soybean Humus. For a side dish sure to compliment grilled chicken or fish try this fresh Bulgur Salad with Edamame. If featuring soybeans in your entrée is more what you had in mind, try Spicy Soybean, Lentil & Carrot Curry or Black Soybean Risotto for a unique main dish.
Soybeans planted on a plot of land produce more protein than if the same plot of land was used to raise cattle.
Henry Ford was a champion for the soybean, pouring millions in the early 1930s into soybean research. By the mid 1930s, following the development of soy-based plastic, at least 2 bushels of soybeans were used in each Ford car. Ford himself was so interested in the bean he wore a suit made entirely out of soybeans and hosted dinner parties where nothing but soybean based foods were served.
David H. Rahm, M.D. is the founder and medical director of The Wellness Center, a medical clinic located in Long Beach, CA. Dr. Rahm is also president and medical director of VitaMedica. Dr. Rahm is one of a select group of conventional medical doctors who have education and expertise in functional medicine and nutritional science. Over the past 20 years, Dr. Rahm has published articles in the plastic surgery literature and educated physicians about the importance of good peri-operative nutrition.