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Soybean

2007 Schools Wikipedia Selection. Related subjects: Food and agriculture

                   iSoybean
           Scientific classification

   Kingdom:   Plantae
   Phylum:    Magnoliophyta
   Class:     Magnoliopsida
   Order:     Fabales
   Family:    Fabaceae
   Subfamily: Faboideae
   Genus:     Glycine
   Species:   G. max

                                Binomial name

   Glycine max
   (L.) Merr.

   The soybean (U.S. and UK) or soya bean (UK) (Glycine max) is a species
   of legume native to Eastern Asia. It is an annual plant that may vary
   in growth habit and height. It may grow prostrate, not growing higher
   than 20 cm (7.8 inches), or even stiffly erect up to 2 meters (6.5
   feet) in height. The pods, stems, and leaves are covered with fine
   brown or gray pubescence. The leaves are trifoliate (sometimes with 5
   leaflets), and the leaflets are 6-15 cm (2-6 inches) long and 2-7 cm
   (1-3 inches) broad; they fall before the seeds are mature. The small,
   inconspicuous, self-fertile flowers are borne in the axil of the leaf
   and are either white or purple. The fruit is a hairy pod that grows in
   clusters of 3-5, with each pod 3-8 cm (1-3 inches) long and usually
   containing 2-4 (rarely more) seeds 5-11 mm in diameter.

   Like corn and some other crops of long domestication, the relationship
   of the modern soybean to wild-growing species can no longer be traced
   with any degree of certainty. It is a cultural variety (a cultigen)
   with a very large number of cultivars. However, it is known that the
   progenitor of the modern soybean was a vine-like plant, that grew prone
   on the ground.

   Beans are classed as pulses whereas soybeans are classed as oilseeds.
   The word soy is derived from the Japanese word shoyu (soy sauce/soya
   sauce).

Physical characteristics

   Soybeans occur in various sizes, and in several hull or seed coat
   colors, including black, brown, blue, yellow, and mottled. The hull of
   the mature bean is hard, water resistant, and protects the cotyledon
   and hypocotyl (or "germ") from damage. If the seed coat is cracked the
   seed will not germinate. The scar, visible on the seed coat, is called
   the hilum (colors include black, brown, buff, gray and yellow) and at
   one end of the hilum is the micropyle, or small opening in the seed
   coat which can allow the absorption of water.

   It is a remarkable fact that seeds such as soybeans, containing very
   high levels of soy protein, can undergo desiccation yet survive and
   revive after water absorption. A.Carl Leopold, son of Aldo Leopold, set
   out twenty years ago to answer this very question at the Boyce Thompson
   Institute for Plant Research at Cornell University. Studying the
   survival of soybeans and corn he found each to have a range of soluble
   carbohydrates protecting the seed's cell viability. Patents were
   awarded to him in the early 1990s on techniques for protecting
   "biological membranes" and proteins in the dry state.

Chemical composition of the seed

   The oil and protein content together account for about 60% of dry
   soybeans by weight; protein at 40% and oil at 20%. The remainder
   consists of 35% carbohydrate and about 5% ash. Soybean cultivars
   comprise approximately 8% seed coat or hull, 90% cotyledons and 2%
   hypocotyl axis or germ.

   The majority of soy protein is a relatively heat-stable storage
   protein. It is this heat-stability of the soy protein that enables soy
   food products requiring high temperature cooking, such as tofu, soymilk
   and textured vegetable protein (soy flour) to be made.

   The principal soluble carbohydrates, saccharides, of mature soybeans
   are the disaccharide sucrose(range 2.5-8.2%), the trisaccharide
   raffinose( 0.1-1.0%) composed of one sucrose molecule connected to one
   molecule of galactose, and the tetrasaccharide stachyose(1.4 to 4.1%)
   composed of one sucrose connected to two molecules of galactose. While
   the oligosaccharides raffinose and stachyose protect the viability of
   the soybean seed from desiccation{see above section on physical
   characteristics} they are not digestible sugars and therefore
   contribute to flatulence and abdominal discomfort in humans and other
   monogastric animals. Undigested oligosaccharides are broken down in the
   intestine by native microbes producing gases such as carbon dioxide,
   hydrogen, nitrogen, methane, etc.

   Since soluble soy carbohydrates are found mainly in the whey and are
   broken down during fermentation, soy concentrate, soy protein isolates,
   tofu, soy sauce, and sprouted soybeans are without flatus activity. On
   the other hand, there may be some beneficial effects to ingesting
   oligosaccharides such as raffinose and stachyose, namely, encouraging
   indigenous bifidobacteria in the colon against putrefactive bacteria.

   The insoluble carbohydrates in soybeans consist of the complex
   polysaccharides cellulose, hemicellulose, and pectin. The majority of
   soybean carbohydrates can be classed as belonging to dietary fibre.

Cultivation

   Varieties of soybeans are used for many purposes.
   Enlarge
   Varieties of soybeans are used for many purposes.

   Soybeans are an important global crop. It is grown for its oil and
   protein. The bulk of the crop is solvent extracted for vegetable oil
   and then defatted soy meal is used for animal feed. A very small
   proportion of the crop is consumed directly for food by humans. Soybean
   products, however, appear in a large variety of processed foods.

   Soybeans have been a crucial crop in eastern Asia since long before
   written records, and they are still a major crop in China, Korea, and
   Japan today. Soy was not actually used as a food item until they
   discovered fermentation techniques around 2000 years ago. Prior to
   fermented products such as soy sauce, tempeh, natto, and miso, soy was
   considered sacred for its use in crop rotation as a method of fixing
   nitrogen. The plants would be plowed under to clear the field for food
   crops. Soy was first introduced to Europe in the early 1700s and the
   United States in 1765, where it was first grown for hay. Benjamin
   Franklin wrote a letter in 1770 mentioning sending soybeans home from
   England. Soybeans did not become an important crop outside of Asia
   until about 1910. In America, soy was considered an industrial product
   only and not utilized as a food prior to the 1920's.

   Cultivation is successful in climates with hot summers, with optimum
   growing conditions in mean temperatures of 20 °C to 30 °C (68°F to
   86°F); temperatures of below 20 °C and over 40 °C (68 °F, 104 °F)
   retard growth significantly. They can grow in a wide range of soils,
   with optimum growth in moist alluvial soils with a good organic
   content. Soybeans, like most legumes perform nitrogen fixation by
   establishing a symbiotic relationship with the bacterium Bradyrhizobium
   japonicum ( syn. Rhizobium japonicum; Jordan 1982). However, for best
   results an inoculum of the correct strain of bacteria should be mixed
   with the soybean (or any legume) seed before planting. Modern crop
   cultivars generally reach a height of around 1 m (3 ft), and take
   between 80-120 days from sowing to harvesting.
   Top Soybean Producers
   in 2005
   (million metric tons)
   Flag of United States  United States      83.9
   Flag of Brazil  Brazil                    52.7
   Flag of Argentina  Argentina              38.3
   Flag of People's Republic of China  China 17.4
   Flag of India  India                      6.6
   Flag of Paraguay  Paraguay                3.5
   Flag of Canada  Canada                    3.0
   Flag of Bolivia  Bolivia                  1.7
   Flag of Italy  Italy                      0.5
   World Total                               214.3
   Source:
   UN Food & Agriculture Organisation
   (FAO)

   Soybeans are native to southeast Asia, but 45 percent of the world's
   soybean area, and 55 percent of production, is in the United States.
   The U.S. produced 75 million metric tons of soybeans in 2000, of which
   more than one-third was exported. Other leading producers are Brazil,
   Argentina, China, and India.

   Environmental groups, such as Greenpeace and the WWF, have reported
   that both soybean cultivation and the threat to increase soybean
   cultivation in Brazil is destroying huge areas of Amazon rainforest and
   encouraging deforestation. Besides destruction of the rainforest, it
   destroys unique biodiversity and causes a billion dollar's loss on
   technology from bionics revenue. American soil scientist, Dr. Andrew
   McClung, who first showed that the infertile Cerrado region of Brazil
   could grow soybeans, was awarded the 2006 World Food Prize on October
   19,2006.

   The first research on soybeans in the United States was conducted by
   George Washington Carver at Tuskegee, Alabama, but he decided it was
   too exotic a crop for the poor black farmers of the South so he turned
   his attention to peanuts. Peanuts, soybeans, or other legume plants
   that would replenish the soil with nitrogen and minerals were planted
   for two years and then cotton on the third year. A two-year rotation
   system alternating maize

Uses

   Soybeans can be broadly classified as "vegetable" (garden) or field
   (oil) types. Vegetable types cook more easily, have a mild nutty
   flavor, better texture, are larger in size, higher in protein, and
   lower in oil than field types. Tofu and soymilk producers prefer the
   higher protein cultivars bred from vegetable soybeans originally
   brought to the United States in the late 1930s. The "garden" cultivars
   are generally not suitable for mechanical combine harvesting because
   they have a tendency for the pods to shatter on reaching maturity.

   Among the legumes, the soybean, also classed as an oilseed, is
   pre-eminent for its high (38-45%) protein content as well as its high
   (20%) oil content. Soybeans are the leading agricultural export in the
   United States. The bulk of the soybean crop is grown for oil
   production, with the high-protein defatted and "toasted" soy meal used
   as livestock feed. A smaller percentage of soybeans are used directly
   for human consumption.

   Soybeans may be boiled whole in their green pod and served with salt,
   under the Japanese name edamame ( IPA pronunciation: [eda-maa-me]).
   Soybeans prepared this way are a popular local snack in Hawai'i, where,
   as in China, Japan, and Korea the bean and products made from the bean
   ( miso, natto, tofu, douchi, doenjang, ganjang and others) are a
   popular part of the diet. In Korean cuisine, soybean sprouts (kongnamul
   (hangul:콩나물)) are also used in a variety of dishes.

   The beans can be processed in a variety of ways. Common forms of soy
   (or soya) include soy meal, soy flour, " soy milk", tofu, textured
   vegetable protein (TVP, which is made into a wide variety of vegetarian
   foods, some of them intended to imitate meat), tempeh, soy lecithin and
   soybean oil. Soybeans are also the primary ingredient involved in the
   production of soy sauce (or shoyu).
   Soybeans grow throughout Asia and North and South America.
   Enlarge
   Soybeans grow throughout Asia and North and South America.

Genetic Modification

   Soybeans are one of the "biotech food" crops that are being genetically
   modified, and GMO soybeans are being used in an increasing number of
   products. Monsanto is the world's leader in genetically modified soy
   for the commercial market. In 1995, Monsanto introduced " Roundup
   Ready" (RR) soybeans that have had a complete copy of a gene plasmid
   from the bacteria, Agrobacterium sp. strain CP4, inserted, by means of
   a gene gun, into its genome that allows the transgenic plant to survive
   being sprayed by this non-selective, glyphosate-based herbicide.
   Roundup kills conventional soybeans. RR soybeans allow a farmer to
   reduce tillage or even to sow the seed directly into an unplowed field,
   known as 'No Plow' tillage, greatly reducing soil erosion.

   In 1997, 81% of all soybeans cultivated for the commercial market were
   genetically modified. As with other "Roundup Ready" crops, concern is
   expressed over damage to biodiversity.

   Archer Daniels Midland (ADM) is among the largest processors of
   soybeans and soy products. ADM along with DOW, DuPont and Monsanto
   support the industry trade associations United Soybean Board (USB) and
   Soyfoods Association of North America (SANA). These trade associations
   have increased the consumption of soy products dramatically in recent
   years.

   The dramatic increase is largely credited to the Food and Drug
   Administration's (FDA) approval of health claims for soy which very
   likely is unfounded (see below: #Reduce Cholesterol?). Since the bulk
   of the soy grown in the US is GMO variety the chief beneficiaries of
   the increase are the biotech seed companies. Dr. Jane E. Henney who was
   the FDA commissioner at the time, now sits on the board of biotech
   giant Astra Zeneca. Many top agency officials from the Bush
   Administration, have been under criticism for close ties to industry
   and possible financial conflicts of interest. The former USDA Secretary
   of Agriculture, Daniel Robert Glickman, also left to accept seats on
   the boards of soy related companies including Hain Foods.

   From 2001 to 2004, food manufacturers in the US introduced over 1600
   new foods with soy as an ingredient, averaging 400 new products per
   year, according to the Mintel’s Global New Products Database.

   From 1992 to 2003, soyfoods sales have experienced a 15% compound
   annual growth rate, increasing from $300 million to $3.9 billion over
   11 years, as new soyfood categories have been introduced, soyfoods have
   been repositioned in the market place, and new customers have selected
   soy for health and philosophical reasons. Dramatic growth followed the
   FDA approval of a health claim linking soy with heart disease
   reduction.

Oil

   In processing soybeans for oil extraction and subsequent soy flour
   production, selection of high quality, sound, clean, dehulled yellow
   soybeans is very important. Soybeans having a dark colored seed coat,
   or even beans with a dark hilum will inadvertently leave dark specks in
   the flour, an undesirable factor when used in food products. All
   commercial soybeans in the United States are yellow or yellow brown.

   To produce soybean oil, the soybeans are cracked, adjusted for moisture
   content, rolled into flakes and solvent-extracted with commercial
   hexane. The oil is then refined, blended for different applications,
   and sometimes hydrogenated. Soybean oils, both liquid and partially
   hydrogenated, are exported abroad, sold as "vegetable oil," or end up
   in a wide variety of processed foods. The remaining soybean husks are
   used mainly as animal feed.

   The major unsaturated fatty acids in soybean oil triglycerides are
   linolenic acid,C18:3; linoleic acid, C-18:2; and oleic acid,C-18:1.
   Soybean oil has a relatively high proportion, 7-10%, of oxidation prone
   linolenic acid, which is an undesirable property for continuous
   service, such as in a restaurant. Two companies, Monsanto and DuPont/
   Bunge in 2004 introduced low linolenic, (C18:3; cis-9, cis-12, cis-15
   octadecatrienoic acid) Roundup Ready soybeans: the former introduced a
   new soybean seed variety called "Vistive" and the latter Pioneer seed
   variety 93M20. Dupont/Bunge is marketing its low linolenic soybean oil
   under the brand name Nutrium. The idea is that reducing or eliminating
   the triple unsaturated fatty acid, linolenic, also eliminates the
   tendency to be a paint-like drying oil producing noticeable rancidity.
   In the past hydrogenation reduced the unsaturation in linolenic acid
   but produced the unnatural trans fatty acid trans fat configuration
   whereas in nature the configuration is cis.

   One unintended consequence of moving away from partially hydrogenated
   soybean oil (containing trans fatty acids) is the switch to partially
   saturated palm oil for frying, especially in China. This fact is
   resulting in a severe threat of deforestation to pristine forests in
   Indonesia followed by the planting of oil palm plantations.

   In the 2002-2003 growing season, 30.6 million metric tons of soybean
   oil were produced worldwide, constituting about half of worldwide
   edible vegetable oil production, and thirty percent of all fats and
   oils produced, including animal fats and oils derived from tropical
   plants.

Meal

   Soybean meal, the material remaining after solvent extraction of
   soybean flakes, with a 50% soy protein content, toasted (a misnomer
   because the heat treatment is with moist steam), and ground, in a
   hammer mill, provided the energy for the American revolution, beginning
   in the 1930s, of growing farm animals such as poultry and swine on an
   industrial scale; and more recently the aquaculture of catfish.

Flour

   Soy flour refers to defatted soybeans where special care was taken
   during desolventizing (not toasted) in order to minimize denaturation
   of the protein to retain a high Nitrogen Solubility Index (NSI), for
   uses such as extruder texturizing (TVP). It is the starting material
   for production of soy concentrate and soy protein isolate.
     * Defatted soy flour, is obtained from solvent extracted flakes, and
       contains less than 1% oil.
     * Full-fat soy flour, is made from unextracted, dehulled beans, and
       contains about 18% to 20% oil. Due to its high oil content a
       specialized Alpine Fine Impact Mill must be used for grinding
       rather than the more common hammermill.
     * Low fat soy flour, is made by adding back some oil to defatted soy
       flour. The lipid content varies according to specifications,
       usually between 4.5% and 9%.
     * High fat soy flour, is produced by adding back soybean oil to
       defatted flour, at the level of 15%.
     * Lecithinated soy flour, is made by adding soybean lecithin to
       defatted, low fat or high fat soy flours to increase their
       dispersibility and impart emulsifying properties. The lecithin
       content varies up to 15%.

Infant formula

   Infant formulas based on soy are used by lactose-intolerant babies; and
   for babies that are allergic to human milk proteins and cow milk
   proteins. The formulas are sold in powdered, ready to feed, or
   concentrated liquid forms.

   It has been recommended internationally by pediatric associations that
   soy formulas not be used as the primary or sole source of nutrition for
   infants due to the high risk of several deficiencies including calcium
   and zinc.

Substitute for existing products

   Many traditional dairy products have been imitated using processed
   soybeans, and imitation products such as " soy milk," "soy yogurt" and
   "soy cream cheese" are readily available in most supermarkets. These
   imitation products are derived from extensive processing to produce a
   texture and appearance similar to the real dairy-based ones. Soy milk
   does not contain significant amounts of calcium, since the high calcium
   content of soybeans is bound to the insoluble constituents and remains
   in the pulp. Many manufacturers of soy milk now sell calcium-enriched
   products as well.

Other products

   Soybeans are also used in industrial products including oils, soap,
   cosmetics, resins, plastics, inks, crayons, solvents, clothing, and
   biodiesel. Soybeans are also used as fermenting stock to make a brand
   of vodka.

   Henry Ford promoted the soybean, helping to develop uses for it both in
   food and in industrial products, even demonstrating auto body panels
   made of soy-based plastics. Ford's interest lead to 2 bushels of
   soybeans being used in each Ford car as well as products like the first
   commercial soy milk, ice cream and all-vegetable non-dairy whipped
   topping.

   The Ford development of so called soy-based plastics was based on the
   addition of soybean flour and wood flour to phenolformaldehyde
   plastics.

   In 1931 Ford, who said, "most people dig their graves with their
   teeth", hired the chemists Robert Boyer and Frank Calvert in a "Quest"
   for artificial silk. They succeeded in making a textile fibre of spun
   soy protein fibers, hardened or tanned in a formaldehyde bath which was
   given the name Azlon by the Federal Trade Commission. Pilot plant
   production of Azlon reached 5000 pounds per day in 1940, but never
   reached the commercial market. However, Henry Ford did have the "now
   famous" suit made for him of Azlon which he wore on special occasions.
   The winning textile fibre in the "Quest" for artificial silk was, of
   course, Nylon a synthetic polyamide or artificial protein discovered in
   1935 by Wallace H.Carothers at DuPont. [Soybeans and Soybean Products,
   Vol.II,edited by K.H. Markley,1951]

   Today, very high quality textile fibers are made commercially from
   okara or soy pulp, a by- product of tofu production.

Nutrition

Protein

   Soybeans are a source of complete protein. A complete protein is one
   that contains significant amounts of all the essential amino acids that
   must be provided to the human body because of the body's inability to
   synthesize them. For this reason, soy is important to many vegetarians
   and vegans. However, the phrase complete protein can be a bit
   misleading since proteins vary in their protein values. Whole eggs have
   a biological value of 100 versus a 74 for soy. Soy protein is similar
   to that of other legume seeds, but has the highest yield per square
   meter of growing area, and is the least expensive source of dietary
   protein.

   The original Protein Efficiency Ratio PER method of measuring soy
   protein quality was found to be flawed for humans because the young
   rats used in the study have higher relative requirements for
   sulfur-containing amino acids. The FAO/WHO (1990) adapted another
   method: protein digestibility corrected amino acid score. Based on this
   method, soy protein is considered to have a similar equivalent in
   protein quality to whey. Egg white has a score of 1.00, isolated soy
   protein 0.92, soy concentrate 0.99, beef 0.92. The digestibility of
   some soyfoods are as follows: steamed soybeans 65.3%, tofu 92.7%, soy
   "milk" 92.6%, soy protein isolate 93–97% The PDCAAS is different to
   that the PER and the BV. The PER was based upon the amino acid
   requirements of growing rats, which noticeably differ to that of
   humans. The biological value method uses nitrogen absorption as a
   basis. However, it does not take into account certain factors
   influencing the digestion of the protein. BV is likely the better
   formula used when calculating protein for muscle growth and synthesis
   in humans. The scientific method for measuring protein is the
   biological value methodology which is an accurate indicator of
   biological activity for protein quality and utilization in humans.

   The table below shows the Biological Value rating of various common
   proteins.
     * Isolated Whey: 104
     * Whole Egg: 100
     * Cow’s Milk: 91
     * Egg Whites: 88
     * Fish: 83
     * Casein: 80
     * Beef: 80
     * Chicken: 79
     * Soy: 74
     * Wheat Gluten: 54
     * Kidney Beans: 49

   soy protein

The nutritional value of soy protein

   Soybeans are a source of complete protein. Soybean protein is
   essentially identical to that of other legume pulse {that is to say
   legume proteins in general, consist of 7S and 11S storage proteins}
   vegetable proteins. Additionally, soy protein has the highest yield per
   square meter of growing area, and is the least expensive source of
   dietary protein. A complete protein is one that contains significant
   amounts of all the essential amino acids that must be provided to the
   human body because of the body's inability to synthesize them. For this
   reason, soy is important to many vegetarians and vegans. However, the
   phrase 'complete protein' is not entirely agreed-upon in usage by the
   scientific community.

   The digestibility of some soyfoods are as follows: steamed soybeans
   65.3%, tofu 92.7%, soy "milk" 92.6%, soy protein isolate 93–97%. Some
   studies on rats have indicated that the biological value and
   digestibility of soy protein isolates is comparable in nutritional
   value to animal proteins such as casein, particularly when enriched
   with the sulfur-containing amino acid methionine.

   Lafayette B. Mendel and Morris S. Fine of the Sheffield Laboratory of
   Physiological Chemistry at Yale University made the observation in the
   September 1911 edition of the Journal of Biological Chemistry that
   soybeans produce a positive nitrogen (N) balance in a human subject
   when they conducted a study to determine the utilization of legume
   proteins. The treatment called for 5 days of a 2400 calorie diet
   consisting of meat, eggs, nut butter, potatoes and fruit, followed by 6
   days where 90.5% of total nitrogen was supplied by soybeans, and then
   another 5 days of the first diet, minus the nut butter. They discovered
   that the soy bean nitrogen is "distinctly (if only slightly) less well
   utilized than that of the preceding and suceeding mixed diets".

   When measuring the nutritional value of protein, the original Protein
   Efficiency Ratio PER method first proposed by Osborne and Mendel in
   1917, and the most widely used method, until 1990, for the biological
   evaluation of protein quality was found to be flawed for humans because
   the young rats used in the study have higher relative requirements for
   sulfur-containing amino acids. As such the analytical method that is
   universally recognized by the FAO/WHO (1990) as well as the FDA, USDA,
   United Nations University (UNU) and the National Academy of Sciences
   when judging the quality of protein is Protein Digestibility Corrected
   Amino Acid Score, as it is viewed as accurately measuring the correct
   relative nutritional value of animal and vegetable sources of protein
   in the diet. Based on this method, soy protein is considered to have a
   similar equivalent in protein quality to animal proteins. Egg white has
   a score of 1.00, beef 0.92, isolated soy protein 0.92, and soy
   concentrate 0.99. In 1990 at a FAO/WHO meeting it was decided that
   proteins having values higher than 1.0 would be rounded or "leveled
   down" to 1.0 as scores above 1.0 are considered to indicate that the
   protein contains essential amino acids in excess of the human
   requirements. The approach of 'capping off' scores at 1.0 as the
   highest possible rating implies injustice to high-quality proteins
   which can compensate for low-quality ones by virtue of their high
   content of essential amino acids. Egg has an actual PDCAA score of 1.19
   compared to 0.92 for isolated soy protein, however when leveled down,
   they appear much closer.

Biological value of soy protein

   Another measure of a protein's use in nutrition is the Biological Value
   scale. The Biological Value method, which dates back to 1911 relies on
   nitrogen retention as an indicator of protein quality.

   According to the 1972 publication Soybeans: Chemistry and Technology,
   isolated soy protein has an average biological value of 71. Compare
   this to the average biological value for other soy products, as well as
   different foodstuffs:
     * White flour: 41
     * Full-fat soy flour: 64
     * Soybean curd (tofu): 64
     * Whole wheat: 64
     * Immature bean: 65
     * Beef: 74.3
     * Fish: 76
     * Defatted soy flour: 81
     * Rice: 83
     * Cheese: 84
     * Cow milk: 90
     * Soybean milk: 91
     * Chicken egg: 94
     * Human milk: 95
     * Whole bean: 96

Vitamins and minerals

   Toasted soybeans
   Enlarge
   Toasted soybeans

   Of any studied legume, whole soybeans have the highest levels of phytic
   acid, an organic acid and mineral chelator present in many plant
   tissues, especially bran and seeds, which binds to certain ingested
   minerals: calcium, magnesium, iron, and especially zinc—in the
   intestinal tract, and reduces the amount the body assimilates. For
   people with a particularly low intake of essential minerals, especially
   young children and those in developing countries, this effect can be
   undesirable. However, dietary mineral chelators help prevent
   over-mineralization of joints, blood vessels, and other parts of the
   body, which is most common in older persons.

   Consumption of soy may also reduce the risk of colon cancer, possibly
   due to the presence of sphingolipids.

The role of soyfoods in disease prevention

Omega-3 fatty acids

   Omega-3 fatty acids, for example, linolenic acid C18-3, all cis,
   9,12,15 octadecatrienoic acid (where the omega-3 refers to carbon
   number 3 counting from the hydrocarbon tail whereas C-15 refers to
   carbon number 15 counting from the carboxyl acid head) are special fat
   components that benefit many body functions. For instance, they inhibit
   blood clotting. Soybean oil is one of the only common vegetable oils
   that contains a significant amount of omega-3s; others include canola,
   walnut, and flax.

Isoflavones

   Soybeans also contain isoflavones, a type of phytoestrogen, that are
   considered by some nutritionists and physicians to be useful in the
   prevention of cancer and by others to be carcinogenic and endocrine
   disruptive. Soy's high levels of phytoestrogens are the subject of
   heated debate and controversy. They are also blamed for some thyroid
   and reproductive health problems. Isoflavones are polyphenol compounds,
   produced primarily by beans and other legumes, including peanuts and
   chickpeas.

   Isolated phytoestrogen-like isoflavones are an active research area. A
   paper in the Proceedings of the National Academy of Sciences studied
   the effect of the isolated soy isoflavones genistein and daidzein
   (commonly found in dietary supplements and infant formulas) on adult
   mice with their ovaries removed. The study found the mice had thymic
   and immune system abnormalities and reduction in immune system
   activity. The article suggests further research into human
   phytoestrogen response is warranted.

   From a website that advertises saliva pH alkalinity as a form of cancer
   protection:

   "Researchers Daniel Doerge and Daniel Sheehan, two of the FDA's experts
   on soy, signed a letter of protest, which points to studies that show a
   link between soy and health problems in certain animals. The two say
   they tried in vain to stop the FDA approval of soy because it could be
   misinterpreted as a broader general endorsement beyond benefits for the
   heart."

   The FDA has since publicly rejected these claims due to lack of
   evidence and cite numerous studies that uphold the health benefits of
   soy foods.

Reduce cholesterol?

   In 1995, the New England Journal of Medicine (Vol. 333, No. 5)
   published a report from the University of Kentucky entitled,
   "Meta-Analysis of the Effects of Soy Protein Intake on Serum Lipids."
   It was financed by the PTI division of DuPont,"The Solae Co." St.
   Louis, Missouri, a soy producer and marketer. This meta-analysis
   concluded that soy protein is correlated with significant decreases in
   serum cholesterol, Low Density Lipoprotein LDL (bad cholesterol) and
   triglyceride concentrations. However, High Density Lipoprotein HDL(good
   cholesterol) did not increase by a significant amount. Soy
   phytoestrogens ( isoflavones: genistein and daidzein) adsorbed onto the
   soy protein were suggested as the agent reducing serum cholesterol
   levels. On the basis of this research PTI, in 1998, filed a petition
   with FDA for a health claim that soy protein may reduce cholesterol and
   the risk of heart disease. It should be noted that only subjects with
   serum cholesterol of 250mg/dl and higher showed any improvement in the
   study.

   The FDA granted this health claim for soy: "25 grams of soy protein a
   day, as part of a diet low in saturated fat and cholesterol, may reduce
   the risk of heart disease." One serving, (1 cup or 240 mL) of soy milk,
   for instance, contains 6 or 7 grams of soy protein. Solae resubmitted
   their original petition, asking for a more vague health claim, after
   their original was challenged and highly criticized. Solae also
   submitted a petition for a health claim that soy can help prevent
   cancer. They quickly withdrew the petition for lack of evidence and
   after more than 1000 letters of protest were received.

   In January, 2006 an American Heart Association review (in the journal
   Circulation) of a decade long study of soy protein benefits casts doubt
   on the FDA allowed "Heart Healthy" claim for soy protein. This review
   of the literature compared soy protein and its component isoflavones
   with casein (isolated milk protein), wheat protein, and mixed animal
   proteins. The review panel also found that soy isoflavones have not
   been shown to reduce post menopause "hot flashes" in women and the
   efficacy and safety of isoflavones to help prevent cancers of the
   breast, uterus or prostate is in question. Thus, soy isoflavone
   supplements in food or pills is not recommended. Among the conclusions
   the authors state, "In contrast, soy products such as tofu, soy butter,
   soy nuts, or some soy burgers should be beneficial to cardiovascular
   and overall health because of their high content of polyunsaturated
   fats, fibre, vitamins, and minerals and low content of saturated fat.
   Using these and other soy foods to replace foods high in animal protein
   that contain saturated fat and cholesterol may confer benefits to
   cardiovascular health."

   The original paper is in the journal Circulation: January 17,2006

Soy controversy

Phytoestrogen

   Soybeans are the most common source of isoflavones and the major
   isoflavones in soybean are genistein and daidzein. Soybean isoflavones
   (isoflavonoids) are the primary sources of phytoestrogens in the human
   diet that mimic estrogen. Plant lignans associated with high fibre
   foods such as cereal brans and beans are the principal precursor to
   mammalian lignans which have an ability to bind to human estrogen
   sites. The best source of lignans is flax seed. Soybeans are a
   significant source of mammalian lignan precursor secoisolariciresinol
   containing 13-273 µg/100 g dry weight. Another phytoestrogen, in the
   human diet, with estrogen activity is coumestans but much less well
   studied which are found in beans, split-peas, with the best sources
   being alfalfa, clover, and soybean sprouts. Coumesterol, an isoflavone
   coumarin derivative is the only coumestan in foods.

Phytoestrogen in men

   Because of the phytoestrogen content, some studies indicate that there
   is a correlation between a soybean-rich diet and a decrease in the
   level of testosterone in men, although these findings are
   controversial.

   A study carried out at the Royal Victoria Hospital in Belfast linked
   soy to male infertility, including damage of reproductive capability
   already caused during childhood. The study also points out that "soy is
   not just consumed by vegetarians, it is contained in a lot of everyday
   processed foods."

Phytoestrogen in women

   A 2001 study determined that women with current or past breast cancer
   should be aware of the risks of potential tumor growth when taking soy
   products.

   A 2006 study reviewed the relationship with soy and breast cancer. To
   summarize, the research recommendation is that the impact of
   isoflavones on breast tissue needs to be evaluated at the cellular
   level in women at high risk for breast cancer.

Phytoestrogen in infant formula

   There are some studies that state that a phytoestrogen in soy can lead
   to alterations in the proliferation and migration of intestinal cells.
   The effects of these alterations are unknown. However, some studies
   conclude there are no adverse effects in human growth, development, or
   reproduction as a result of the consumption of soy-based infant
   formula. Other studies conclude that more research is needed to answer
   the question of what effect phytoestrogens have on infants.

Allergens

   With the increased use of soybean in western diet comes also a danger
   of food allergies. About 8% of children in the USA are allergic to
   soybean proteins. The major soy allergen has been identified by
   scientists at USDA. Both transgenic and conventional soybean varieties
   without the allergenic protein have been prepared, and hopefully will
   soon reach the market. This will be particularly important for
   preparation of baby formulas, since dual allergy to both milk and soy
   proteins is not uncommon. Soya allergy, typically, will manifest itself
   approximately a day after consumption of the beans. Common symptoms are
   urticaria, rash, itching, and redness of the skin.

Thyroid effects

   Eating as little as 35 grams of soy such as tofu per day (just 10 grams
   over the amount recommended by the U.S. Food and Drug Administration)
   has been proven to cause thyroid function suppression in previously
   healthy adult women and men.

Cancer

   A 1985 animal study showed that young rats fed large amounts of soy
   products as their primary food source showed an increased risk of
   pancreatic cancer. This is probably because rats are extremely
   sensitive to dietary protease inhibitors like those found in soybeans,
   which can disrupt the action of digestive enzymes needed to break down
   protein. This condition has not been found in many other animals, and
   is not known to occur in humans.
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