Soy

The soy plant produces nutritious beans, which offer many varied health benefits. Find out why this precursor to tofu has earned a place in the spotlight.

Quick Facts
General Information
  • Common name(s)Soy, soy bean, soya bean, soya, soja, soja bean
  • TCM nameHuang Da Dou
  • Scientific nameGlycine max
  • Geographic distributionTemperate regions worldwide
  • Plant typeHerb
  • Native regionEast Asia
  • Main producer(s)United States of America
  • Main Economic UseFood industry
Soy

Researchers believe that soy was first used in China, Korea, and Japan as early as 5000 BCE. Influenced by the vegetarian teachings in Buddhism, the Han dynasty (202 BCE to CE 220), roughly contemporaneous with ancient Rome, was the period in which the Chinese invented tofu and other fermented soy products that now are main part of the Asian diet. However, soybeans did not begin spreading throughout the rest of the world until the 18th and 19th centuries; nowadays, it is nutrient-rich global staple.

Medicinal and Nutritional Information

Quick Facts (Medicinal and Nutritional Information)
  • Medicinal actionEstrogenic
  • Key constituentsGenistein, omega-3 fatty acids
  • Ways to useCapsules, Food, Powder
  • Medicinal rating(3) Reasonably useful plant
  • Safety rankingSafe
Soy

Health Benefits of Soy

In addition to being a nutritious element of any meal, among its numerous benefits, soy is well known for its estrogenic and osteoprotective properties that have found a variety of medicinal uses.

Recent studies have shown soy can help by:

  • Relieving symptoms of menopause and PMS. This is due to its ability to mimic estrogen in the body, helping the body cope with fluctuating estrogen levels that characterize menopause and premenstrual syndrome (PMS).

  • Preventing bone loss and osteoporosis. Soy helps to decrease the activation of osteoclasts, the cells that resorb bone. This results in reduced bone loss.

The hypocholesterolemic and cardioprotective properties of soy are also being studied. There's evidence that soy may be beneficial for:

  • Balancing cholesterol levels. It can help reduce LDL cholesterol levels, which are considered unhealthy when too high.

  • Helping to prevent heart disease. Soy has been found to decrease triglyceride levels, a major factor in both heart disease and high cholesterol.

However, the nutritional value of soy is the main reason for its popularity. Its high quality plant based protein content makes it a great alternative for people with dietary restrictions and vegetarians. Soy is the only vegetable food that contains all eight essential amino acids, and its nutritional profile includes high levels of fiber, iron, calcium, zinc, and B vitamins.

How It Works

Soy is rich in isoflavones, namely genistein, a type of phytoestrogen. It is also high in calcium, protein, vitamin C (ascorbic acid), and omega-3 fatty acids. These fatty acids, often referred to as "good fats," are polyunsaturated chains that give soy health benefits. Soy isoflavones have shown a positive influence over cardiovascular health, slightly reducing the concentration of low-density lipoproteins in individuals who had very high levels of cholesterol.

Soy isoflavones can help to help stabilize estrogen levels when there's a deficiency. These isoflavones activate estrogen receptors, though not as strongly as the body's own estrogen (endogenous estrogen). Studies have shown that soy isoflavones increase bone mineral density in postmenopausal women, suggesting that soy consumption may reduce the risk of osteoporosis.

As a protein source, soy also has several therapeutic uses. It can help reduce LDL cholesterol, the "bad" kind, while increasing HDL cholesterol, which is beneficial. This not only because soy can replace cholesterol-heavy meat sources of protein, but also likely due to its omega-3 and isoflavone content.

Furthermore, preliminary studies indicate that one of soy's protein fractions, 7S, may have a role in inhibiting the development of atherosclerosis by acting directly on the artery wall rather than on plasma lipids, or low-density lipoprotein cholesterol receptors.

Soy Side Effects

Soy consumption is generally regarded as safe, even during pregnancy, in the amounts normally found in foods (such as tofu or soybeans). However, long-term use of soy as a dietary supplement can cause stomach pain, bloating, constipation, diarrhea, and menstrual changes.

Soy is one of the most common food allergens. Sensitive people can experience allergic reactions after consuming soy or soy based products. Warning signs include skin rash, itching in the mouth, stuffy or runny nose, nausea and asthma symptoms.

    Cautions

    • Women with hormone-sensitive cancers (breast, ovarian, or uterine cancer), or hormone-sensitive conditions, such as endometriosis, should moderate soy consumption (especially soy supplements) or avoid it altogether.
    • Since soy have anticoagulant properties, people with bleeding disorders or taking drugs that may increase the risk of bleeding should moderate its consumption.
    • People with diabetes or low blood sugar, and those taking drugs, herbs, or supplements that affect blood sugar should be aware that soy may lower blood sugar levels.
    CONTRARY TO POPULAR BELIEF, STUDIES HAVE SHOWN THAT SOY PRODUCTS HAVE NO ADVERSE EFFECTS ON MEN

    How to Consume Soy

    Remedies

    Main soy components (basically protein and isoflavones) are isolated into different formulations that offer particular benefits. It is important to know that, while supplements can be beneficial to take advantage of specific properties of soy, they must be consumed in moderated amounts and according to personal dietary needs.

    Main preparations: capsules, powder, syrup

    • Soy capsules. These capsules offer a high content of isoflavones. They are usually directed to women with estrogen deficiencies, so they can take advantage of the estrogenic properties of soy.
    • Soy powder. This formulation brings a high concentration of soy protein. It is usually taken as a substitute of meat for people with dietary restrictions, and as a complementary source of protein to prevent and treat osteoporosis. 
    • Soy syrup. This homemade estrogen enhancer helps relieve PMS and menopausal symptoms.

    Foods

    The best way to take advantage of all the nutritional benefits of soy is consuming it as food. However, soybeans and their byproducts always should be taken in moderation.

    Main ways: Cooked, vegetable milk, tofu, oil

    • Cooked. Since fresh soybeans (called edamame) aren't eatable, this is a very popular way to consume them and take advantage of their nutrients and fiber content. Compared to other legumes, soybeans are higher in healthy fatty acids and protein, and lower in carbohydrate. Frozen edamame takes four to five minutes in boiling water to be ready, while fresh edamame will take up to six minutes.
    • Soy milk. This is a great way to get soy protein without the fiber. Soy milk can be home made by cooking dried soybeans, blending them with water and straining the mixture through a cheese cloth. However, there are many commercial brands that offer soy milk, plain or in a variety of flavors, often fortified with both calcium and vitamin D.
    • Tofu. Also known as soya curd, tofu is the result of curdling soy milk with a coagulant agent called nigiri. Considered as a soft cheese-like food, tofu is usually packaged in water and should be refrigerated until used. Tofu is rich in protein and B vitamins, which make it a great meat substitute for vegetarians, and it is a much better source of calcium than soy milk.
    • Soy oil. Extracted from the seeds of the soy plant, this is the most popular oil worldwide. It is used in the kitchen and, while it lacks most of soy vitamins, protein and fiber, is rich in polyunsaturated fats, which can help reduce bad cholesterol levels and lower risk of heart disease and stroke. Polyunsaturated fats also contribute vitamin E to the diet, an antioxidant most Americans need more of.

    Buying

    Quick Facts (Buying)
    • Where to buySupermarkets, Farmers' markets, Specialized health stores

    Raw Soybeans

    "Raw" or "green" soy, popularly called edamame, can be found in most large grocery stores around the world. These soybeans have been picked before they are fully ripened in order to present them in the pods, and they should be cooked before consumption.

    Cooked Soy and Soy Derivatives

    The most common way to purchase soybeans is in their cooked form as tofu, soy milk, or other soy-derived products. The cooked soybeans have been prepared with wet heat to destroy the trypsin inhibitors, which can be harmful to humans. Soy sauce is a very popular choice, but should only be consumed in moderation due to its high sodium content.

    Soy Supplements

    Soy supplements are mainly found in specialized health stores, but there is also a wide choice of supplements available for delivery in most places around the world through online retailers. Each brand of soy supplement may come with different concentrations, and they are available in both capsules and powder form.

    Growing

    Quick Facts (Growing)
    • Life cycleAnnual
    • Harvested partsFruit
    • Light requirementsFull sun
    • SoilMedium (loam), Loamy sand
    • Soil pH6.1 – 6.5 (Slightly acidic), 6.6 – 7.3 (Neutral)
    • Growing habitatTemperate climates
    • Pre-germination seed treatmentNone
    • Planting timeEarly spring
    • Plant spacing average0.6 m (1.97 ft)
    • Potential insect pestsAphids, Fungi
    • Potential diseasesMildew, Root rot

    Growing Guidelines

    • Soy plants thrive in full sun and alkaline soils, with a pH of 6.0 - 6.8.
    • Thanks to its ability to fix nitrogen into the soil, it works great when rotating crops or if a plot of land has lost some of its natural fertility.
    • In light or sandy soils, a side-dressing of fertilizer may be needed after heavy rainfalls.
    • Soybeans should be planted after all danger of frost has passed and the soil has warmed (late winter - spring). Poor germina­tion and rot are likely if the soil temperature is below 50°F (10°C). For continuous harvest throughout the summer, seeds should be planted every two or three weeks until mid-summer.

    • In order to let soy grow to its best potential, it should be planted in the ground about one to two inches (2.5 - 5 cm) deep, with two to four inches (5 - 10 cm) left between each plant.
    • Soybeans require 80 - 90 days to harvest. They will be ready when the seeds are fully enlarged, but before they become hardened.

    • Rows of soy are usually grown 24 - 30 inches (61 - 76 cm) apart.

    • It is important to ensure that soy plants are well moisturized and weeded, watered, and fertilized appropriately.

    Additional Information

    Quick Facts (Additional Information)
    • Other usesAnimal feed, Cleaning, Fuel

    Plant Biology

    Soy is an herbaceous annual plant that can grow up to 6 feet (2 m) tall. It possesses trifoliate leaves that usually fall before the seeds are mature, and it also has white, pink, or purple flowers. As the plant matures, each pod produced will contain two to four soy beans each; these beans constitute the most economically and nutritionally valuable part of the soy plant. These beans, like all legumes, are very protein-rich and thus nourishing, and they also contain a large amount of unsaturated fats, leading to the plant's classification by the Food and Agricultural Organization as an oilseed rather than a pulse.

    • Classification
      Soy, or Glycine max, is a member of the Fabaceae family, also known as the Leguminosae family, which includes approximately 19,400 species, making it the third largest land plant family. Plants belonging to this family can grow in numerous conditions, and may be found anywhere except for arctic regions.

      A notable characteristic of the Fabaceae family is the ability of its plants to fix nitrogen into the soil, thanks to rhizobia bacteria, which live in symbiosis among the plants' root systems.
    • Varieties and Subspecies of Soy
      Since Glycine max has been a domesticated crop for many centuries, the wild soybean (Glycine soja) is regarded as a distinct species from modern, edible soy. However, many varieties and cultivars of soy have been developed through selective breeding around the world, and although each may receive different names in specific regions, they can mostly be grouped in yellow, green, back, and white soybeans.

      In 1996, genetically modified (GMO or transgenic) soybeans were also grown for the first time, and they make up for most of the world's yearly soy production today. Genetically modified soy remains a controversial issue because of alleged - but unproven - health and environmental concerns. However, many varieties of GMO soy are more protein-dense and have allowed for improved yields and more resistant crops at cheaper prices, contributing to the effort to eradicate world hunger, especially in areas of famine.

    Economic Data

    Because of its versatility, soy is of high economic importance throughout the world. It is used to produce soy oil, soy meal for human and livestock consumption, bio fuel, and herbal supplements. The United States is the largest producer of the soybean, with roughly 75 million metric tons of soybeans produced in that country alone each year.

    Other Uses

    • Alimentary Industry. Soy proteins are used in infant formulas and enteral nutrition products, as ingredients in meat products, and as protein supplements. Soy fiber is used in enteral nutrition products and some bakery goods.

    • Packaging. Soy is used when packaging many food products in order to preserve their shelf life.
    • Feed. Soy is a popular ingredient for cattle feed.
    • Fuel. Soy is now being used in the creation of biodiesel fuels as an alternative to gasoline.
    • Household Products. Soy can also be found in lubricants and cleaning products. It's also used in the manufacturing of plywood, carpeting, and upholstery.

    Bibliography

    • Encyclopedia of Herbal Medicine, p. 216
    • American Journal of Clinical Nutrition, Legumes and soybeans: overview of their nutritional profiles and health effects, 1999
    • Phytochemistry, Legumin and Vicilin, Storage Proteins of Legume Seeds, 1976
    • New York University - Langone Medical Center, Soy
    • American College of Allergy, Asthma and Immunology, Soy Allergy
    • Fertility and Sterility, Clinical studies show no effects of soy protein or isoflavones on reproductive hormones in men: results of a meta-analysis, 2010
    • Journal of Perinatal Education, Soy Protein, 2003
    • The Physicians Committee, Soy and Your Health
    • Journal of the American Dietetic Association, Preliminary study: soy milk as effective as skim milk in promoting weight loss, 2007 | Nutritional benefits of soy protein and soy fiber, 1991
    • Hamilton University, Classification and Botanical Description of Legumes
    • American Heart Association, Polyunsaturated Fats
    • American Journal of Botany, Occurrence of low molecular weight and high cysteine containing albumin storage proteins in oilseed of diverse species, 1981
    • Clinical Science, Effect of a Phytoestrogen Food Supplement on Reproductive Health in Normal Males, 2001
    • Environmental Health Perspectives, The Science of Soy: What Do We Really Know?, 2006
    • Prostaglandins, Leukotrines, and Essential Fatty Acids, Protective role of n-3 lipids and soy protein in osteoporosis, 2003
    • The American Journal of Cardiology, A Meta-analysis of the Effect of Soy Protein Supplementation on Serum Lipids, 2006
    • The Cradle of the East, p. 462
    • The Journal of Nutrition, Dietary soy beta-conglycinin (7S globulin) inhibits atherosclerosis in mice, 2004
    • University of Florida, Facts about Flavonoids
    • World Health Organization, Protein Quality Evaluation: Report of the Joint FAO/WHO Expert Consultation
    • Purdue University, Department of Horticulture, Growing Beans in the Home Vegetable Garden