Old ancient soybean,Soy and the dissemination,cultivation...

  seminal trace...Soybean.Glycine max.10:1Extract.Soy isoflavones,Genistein 90%98%M.F.C15 H10O5.CAS.NO:446-72-0,Daidzein 98%M.F.C15 H10O4.CAS.NO:486-66-8.soy isoflavone,Glycine max L.extract.....

   Basic Botanical Data of Soy(Glycine max):

 Official Latin Name: Glycine max
 Biological Name: Sojae praeparatum
 Pharmacopeial Name: Lecithinum ex soya
 Other Names: Soy, Black soybean, Dan dou chi, fermented black soybean,Glycine max, Glycine soja, Soya, Soybeans
 Parts Used: Beans, oil, sauce, and a variety of other forms

 

 Basic Botanical Data of Soy(Glycine max).
 Cultivation and plant history of Soy: Soy and the dissemination:
 Nutrients and Phytochemicals of Soy:
 Soybeans are used in a variety of ways in Asia:
 Soy Active Compounds:
 History of Soy:
 General Health and Functionality of Soy:
  1).Soy and Reduction in Cholesterol:
  2).Soy Improves Digestion:
  3).Soy Treat heart disease:
  4).Soy reduce certain cancers:
  5).Soy is also being studied for possible effectiveness in numerous other conditions, including:
  6).Soy as Bowman-Birk inhibitor (BBI):
  7).Phytoestrogens and Soy Extract:
  8).Dietary Soybean:A Source of Functional Food Ingredients, Soy proteins,Soy carbohydrates,Soy lipids and phytosterols,Soy phytoestrogens,Soy saponins,Soy Isoflavones.
  8.1).Soy proteins
  8.2).Soy carbohydrates:
  8.3).Soy lipids and phytosterols
  8.4).Soy phytoestrogens
  8.5).What are phytoestrogens?
  8.6).Soy saponins
  8.7).Soy Isoflavones:
 Research Update and latest findings of Soy Isoflavones.Daidzein.Daidzin.Genistein.Genistin related.


   Cultivation and plant history of Soy: Soy and the dissemination:

 Soy cultivation is believed to have begun in China; Domesticated in northeastern China from the wild Glycine soja, the earliest evidence of cultivation dating to 3000 years ago. The emperor Shen-nong, who compiled the Medical Bible of the Yellow Emperor (Huang-di nei jing) sometime between 2967 and 2597 B.C.E., counted soybean among the five sacred crops. Since then, both ancient Chinese and contemporary Chinese medical literature have claimed health benefits from soy. During the Ming Dynasty (1368~644 B.C.E.), in his 52-volume Chinese Materia Medica, Li-Shi Zhen recommended soybeans for the treatment of kidney disease, edema, and poisoning. Today soy may be recommended for skin diseases, gastrointestinal disorders, leg ulcer, vitamin deficiency, and pregnancy toxemia (Holt, 1996).
 The cultigen species Glycine max, known as Soybean, was domesticated in northeastern China from the wild Glycine soja, the earliest evidence of cultivation dating back to 1000 BC. In the third century BC, Soybean and Millet were regarded as the most important food crops in northeastern China. Soybean remains an important source of high protein to people in the Far East and Southeast Asia. From the 1700's, European visitors to the Far East started bringing back Soybean seed to Europe and introducing it to the colonies. Soybean started being grown in the USA from 1765 onwards but it was only in World War II with butter shortages and the need for substitutes that the soybean crops really took off and by 1973, the USA was producing three-quarters of the world crop. Maize farmers found that rotating maize with soybeans reduced the need for nitrogen fertilizers because, being legumes, Soybean have Rhizobium bacteria in their roots that convert gaseous nitrogen to nitrogenous compounds.
 Like most plants that have been domesticated, Soybean is mainly self-pollinating which means that people have been able to easily keep separate breeding lines. This has resulted in a large number of different cultivars, differing for instance in seed colour. Domesticated Soybean differs from wild forms in the following chacteristics:
 Plants are taller and more erect; pods do not shatter their seeds early so seeds are not lost before harvest;
 Seeds are larger; seeds have a higher oil content; seeds are more flavoursome; seeds are quicker cooking; and
 Digestibility is greater although there are still problems with digestibility because seeds contain tryptophan inhibitors that lower the availability of amino acids in the seed. These inhibitors can be deactivated through cooking, although overcooking reduces protein quality.

 
   


   Nutrients and Phytochemicals of Soy:

 Soy nuts are highly nutritious and delicious.
 Soy, a staple food in many Asian countries, contains valuable constituents, including protein, isoflavones, saponins, and phytosterols. Soy protein provides essential amino acids. When eaten with rice, Soy provides protein comparable to that found in animal products. Soy is low in fat and cholesterol-free.
 Soy beans are probably the single most versatile crop in the world. They are used to make tofu, soy sauce, miso, alimentary pastes, food oils, baby food, beer, candy, cereals, diet foods, grits, hypo allergenic milk, meat substitutes, noodles, yeast, candy, coffee creamers, pharmaceuticals and on and on.
 Asian diets are traditionally high in soy. The studies of Dr. Mary Jane Minkin, a clinical professor of obstetrics and gynecology at Yale University, concentrated on the high consumption of isoflavones, the phytoestrogens found in soybeans, and their utility to menopausal women.

 


   Soybeans are used in a variety of ways in Asia:

 They are eaten as grean beans and as bean sprouts;
 Mature seeds are treated in a variety of ways including cooking whole seeds, milling or liquefying them;
 They can be made into milk, often used by people allergic to dairy products;
 Tofu or soybean curd, has a cheese-like consistancy and a rather bland taste and can be eaten on its own or used in combination with other foods; and
 Indonesian tempeh, miso and the well known soy sauce are soybean products produced through ferementation using fungal and/or bacterial cultures.
 In the west, soybean oil is used for producing various products including margarine, salad oil and soap. The residual cake from pressing out the oil is a valuable high protein feed for livestock. It is not often realised how much soybean is used directly in everyday food products and indirectly through being fed to livestock.

 


   Soy Active Compounds:

 Soy, a staple food in many Asian countries, contains valuable constituents, including protein, isoflavones, saponins, and phytosterols. Soy protein provides most of the essential amino acids. It is also low in fat and cholesterol-free.
 The isoflavones in soy, primarily genistein and daidzein, have been well researched by scientists for their antioxidant and phytoestrogenic properties. Saponins enhance immune function and bind to cholesterol to limit its absorption in the intestine.
 Phytosterols and other components of soy have been reported to lower cholesterol levels.
 Isoflavones may reduce the risk of hormone-dependent cancers, such as breast and prostate cancer, as well as other cancers. Both animal and human studies have confirmed this.

 


   History of Soy:

 Ancient Chinese books have many references to the use of soy products. The predecessor of miso probably originated in China as a salt- fermented food called Chiang sometime during the Chou dynasty (722- 481 B.C.). At first, the term referred to any protein-rich animal food that was preserved with salt. The substitution of soybeans for meat and fish as the basic protein of chiang was first described in the Chimin Yaushu (535-550 AD) which is the oldest agricultural encyclopedia in the world. From the book's description, it appears that fermented soybean foods had been prepared several centuries before.
 The cultivation of soybeans occurred with the spread of Buddhism, which recommended vegetarianism, during the Han dynasty (206 B.C.-220 A.D.). It was also around 164 B.C. that Lord Liu An of Huai-nan invented the process of making tofu. Miso probably arrived in Korea directly from China around the same time as the introduction of Buddhism, sometime around the sixth century A. D.

 


   General Health and Functionality of Soy:

  1).Soy and Reduction in Cholesterol:

 A meta-analysis study that pooled thirty-eight trials for reanalysis reported that a soy diet led to cholesterol reductions in 89% of the studies. Increasing soy intake was associated with a 23 mg per deciliter drop in total cholesterol levels.

  2).Soy Improves Digestion:

 Miso is used to relieve acid indigestion, symptoms of hangover, and other digestive upsets. Because of this, it is used with ginger and/or garlic to prevent and/or cure colds, improve digestive metabolism, increase resistance to parasite infestations (which tend to occur in an acid environments), and neutralize blood toxins and therefore clear the skin.
 In numerous studies, supplementing diets with soy or replacing animal-derived foods with soy-based foods has been shown to reduce cholesterol levels in individuals who had either high or normal cholesterol. Fats are generally classified as saturated or unsaturated according to their chemical structures. Saturated fats are usually solid at room temperature. Mainly derived from animal sources, saturated fats are more likely to result in high cholesterol levels in the blood.
 In addition to substituting polyunsaturated plant fats for the potentially more harmful saturated animal fats, it is believed that soy may lower cholesterol levels in at least two other ways. First, it may be absorbed before cholesterol in the intestines, thereby blocking some of the cholesterol that would ordinarily be taken up by the body. More cholesterol would then stay in the intestines to eventually be eliminated from the body. In addition, soy may also promote an increase in the secretion of bile acid. Because cholesterol is a major component of bile acid, more cholesterol would be used to produce bile and less cholesterol would circulate in the body. The U.S. Food and Drug Administration (FDA) allows manufacturers to claim cholesterol reduction on package labels if the food supplies at least 6,250 mg (6.25 grams) of soy protein in each serving.


  3).Soy Treat heart disease:

 Soy may also be effective in other ways to prevent some types of heart disease. It may reduce or delay atherosclerosis (hardening of the arteries) by blocking an enzyme that causes blood vessels to lose flexibility. As a result, blood vessels may not get as stiff and plaques -- deposits of blood cells and fatty substances that contribute to hardening of the arteries? may be less likely to form. Chemicals in soy may decrease the tendency of blood components known as platelets to cluster or aggregate. This ?thinning? of the blood also makes the formation of blood clots and plaques less likely. In addition, soy is thought to reduce levels of homocysteine in the body. Homocysteine is an amino acid produced from the breakdown of meat proteins in the body. Although a definite relationship has yet to be established, high levels of homocysteine in the blood have been linked with a higher risk of several conditions ? including coronary heart disease.
 Soy also contains chemicals called isoflavones, which belong to a larger class of plant chemicals known as phytoestrogens. Two of the main isoflavones in soy are known as genistein and daidzein. Because they are shaped like the female hormone estradiol, soy isoflavones attach to estrogen receptors throughout the body -- particularly in the bladder, blood vessels, bones, and heart. For women with normal estrogen levels, soy isoflavones may displace some of the natural estrogens, thus possibly preventing the development of estrogen-dependent cancers of the breast and endometrium. In post-menopausal women, who have generally low blood levels of estrogen, soy may act as hormone replacement, thereby relieving some of the symptoms associated with low estrogen levels. The observation that Oriental women, who generally eat large amounts of soy as compared to women in western societies, have fewer hot flashes and other symptoms of menopause seems to confirm this theory.
 Clinical studies have been inconclusive, however, in determining whether or not soy isoflavones are effective at relieving hot flashes associated with menopause. Some study participants experienced various degrees of relief from hot flashes, while others observed no change. In addition, soy isoflavones may actually accelerate the growth of existing breast tumors. More study is needed to determine whether soy is cancer-preventive for women and whether symptoms of menopause may be relieved by soy.

  4).Soy reduce certain cancers:

 The estrogen-like effects of soy may also reduce the risk of certain other cancers. By blocking enzymes thought to contribute to prostate cancer, soy isoflavones may delay or prevent its development. Additionally, as a good source of dietary fiber, soy may promote regular bowel movements and protect against developing colon cancer. Additionally, various chemicals contained in soy have been shown in animal, laboratory, or human studies to limit the growth of tumors by encouraging the degradation of cancer cells and discouraging the development of new blood vessels that support tumors. Soy is also believed to enhance general function of the immune system, in part due to its antioxidant activity. Antioxidants are thought to protect body cells from damage caused by a chemical process called oxidation. Oxidation produces oxygen free radicals, natural chemicals that may suppress immune function. Results of human studies for these uses of soy are not yet conclusive and further study is needed to prove or disprove its effectiveness for treating them.
 


  5).Soy is also being studied for possible effectiveness in numerous other conditions, including:

 The estrogen-like effect of soy may limit the development of benign prostate hyperplasia (BPH), which is a non-cancerous enlargement of the prostate gland. An enlarged prostate may cause men to experience a weak or interrupted urine stream, dribbling after urinating, or the urge to urinate even after voiding. For most men, BPH is a normal part of aging.
 Taking soy may increase bone density, thereby treating osteoporosis in older men or women. It may have an indirect effect by reducing the levels of certain hormones, as well as a direct effect in preventing breakdown of bone.
 In a study of women with high cholesterol and also diabetes, soy appeared to decrease resistance to insulin, regulate glucagon (the hormone that releases sugar supplies from the liver), and increase stability of blood sugar levels. Animal studies have shown similar results.
 In studies involving Alzheimer?s disease patients, participants who took soy supplements showed improvement in their ability to learn and remember. Although these results are preliminary, it is believed that chemicals in soy may boost the production of an enzyme that appears to be involved in maintaining memory. Soy may also enhance the growth of nerves and delay the deterioration of proteins in the brain. None of these possible effects have been confirmed by further studies.
 Soy is also being studied to treat obesity. Obviously, soy-based food products may be used to replace higher-calorie animal foods; but soy may also have other effects. Preliminary studies in laboratory animals have shown that eating soy products may reduce genetic tendencies to gain weight. The results of one small human study showed that weight loss associated with soy intake may be greater than expected from merely calculating the number of calories consumed.

  6).Soy as Bowman-Birk inhibitor (BBI):

 Another health benefit of soy intake may be through inhibition of angiogenesis by a peptide found in many soy products, referred to as Bowman-Birk inhibitor (BBI). Angiogenesis is the formation of new blood vessels to supply blood and nutrients and to remove metabolic wastes from living tissue. Physiologic angiogenesis is a tightly regulated process important to embryonic development, reproduction and wound healing. Pathologic angiogenesis is a feature of many inflammatory diseases and contributes to the spread of several chronic diseases and may involve excessive or inadequate angiogenesis. Prevention of excessive angiogenesis involves using drugs that inhibit the enzymes required for new blood vessel formation. Stimulation of new blood vessel growth with growth factors is being considered for therapeutic treatment of insufficient angiogenesis for patients with poor wound healing of skin ulcers.
 Data from animal models and cell culture show that angiogenesis can be inhibited by naturally occurring physiologically active compounds, such as BBI. BBI is stable to gastrointestinal digestion and maintains biological activity even after boiling for 10 minutes. BBI is used in the soybean as a defense mechanism against insects, predators and bacterial and viral infections. BBI is a natural inhibitor of several metalloprotease enzymes that lead to the onset and progression of angiogenesis and diseases related to excess production of new blood vessels.
 LSU AgCenter research has shown that BBI at concentrations found in a cup of soymilk can completely prevent the activation of metalloproteinases by binding to the enzymes. These enzymes can be maintained in an inactive form by the presence of low concentrations of BBI. The prevention of metalloprotein-ase activation preserves the integrity of the basal membrane and other tissues and may delay the onset and progression of diabetes complications, periodontal diseases, cancer, arthritis, osteoporosis, psoriasis and AIDS complications. Because treatments for many of these conditions may be costly and ineffective, good nutrition may be the key to prevention. Two advantages for promoting BBI as an inhibitor of angiogenesis are 1) BBI is not perceived as a medicine and has no known side effects in Asian populations who have consumed soy products for generations and appear to have low rates of chronic diseases and 2) food fortification with soybean BBI would be a relatively inexpensive way to deliver BBI over a life pan.
 BBI is a protein with health-enhancing properties that encompass a wide range of human ailments. Consumption of soymilk by the general population may provide health benefits in the intestinal tract and should be encouraged. A cup of soymilk a day may help keep the doctor away.

 

  7).Phytoestrogens and Soy Extract:

 The term phytoestrogens describes plant (or fungal) compounds that can elicit an oestrogenic response in mammals, at least under certain circumstances.
 Phytoestrogens are a group of phytochemicals currently under intense investigation for their role in the management of menopausal symptoms and in the prevention of chronic diseases such as cancer and cardiovascular disease.
 Also, the role of soy beans as a staple food and a major source of phytoestrogens is reviewed and the major soy constituents are identified.

 Phytoestrogens at a glance

 Isoflavones:

 occur principally in legumes
 soybeans and soy-based foods are the main dietary sources
 occur primarily as glycosides in plants
 the main isoflavone glycosides in soy are genistin and daidzin
 the corresponding aglycones are genistein and daidzein

 Lignans:

 primarily found in whole grains and seeds
 weaker phytoestrogens than the isoflavones
 linseed is the richest source
 main lignans in mammals are enterolactone and enterodiol

 Coumestans:

 occur chiefly in leguminous plants
 includes coumestrol, which is the most potent of phytoestrogens
 high levels in clovers, alfalfa and soy-bean sprouts

 Sources of phytoestrogens:

 Many plants, including major food species, contain phytoestrogens.
 Lignans occur in particularly high levels in linseed, but are also found in whole cereals, cereal bran, dried seaweeds, vegetables, legumes, and fruits.
 Plant lignans are not themselves oestrogenic, but rather serve as precursors to the so-called mammalian lignans, which form in mammals as a result of bacterial metabolism of the plant lignans in the gut.
 The main mammalian lignans are enterolactone and enterodiol; these form from the plant lignan precursors matairesinol and secoisolariciresinol.
 As is characteristic of phytoestrogens, both enterolactone and enterodiol can have either oestrogenic or anti-oestrogenic activity under different circumstances, as outlined below.
 The coumestans occur chiefly in leguminous plants. The main phytoestrogen in this group is coumestrol, which is also regarded as the most potent of phytoestrogenic compounds.

 

  8).Dietary Soybean:A Source of Functional Food Ingredients, Soy proteins,Soy carbohydrates,Soy lipids and phytosterols,Soy phytoestrogens,Soy saponins,Soy Isoflavones.

 Soy flour and more highly purified soy proteins contain a number of constituents that can be used in combating a variety of diseases. Soy isofla-vones may prevent diseases associated with post-menopausal women such as osteoporosis and coronary heart disease. A peptide found in soy flour is a potential anti-carcinogen. LSU AgCenter research has been directed at extraction, purification, stability testing and functional activity of these compounds.
 Soybeans have been a major food source in Asian cuisines for centuries. Soybean cultivation as a crop began in northern China more than 5,000 years ago and slowly spread into southern China and Southeast Asia. Early Chinese writings by the Emperor Sheng-Nung in 2838 BC include a description of soybeans as one of the five sacred crops along with rice, wheat, barley and millet. Later poets celebrated the benefits of soybeans and their service to humanity in China. Soybeans were processed into many food items such as tofu, miso, tempeh and soy sauce, which were part of the daily diet. Fermented soy products were used medicinally in many parts of Asia, and moldy soybean curds have been used for more than 3,000 years to treat skin infections.
 Today, soybean consumption is still much higher in Asian countries than in the United States. Because lower rates of heart disease, some cancers and osteoporosis are associated with higher intakes of soy products, scientists have started to examine soy as a functional food. The relationship between soy intake and heart disease was the first focus of research because heart disease rates are much lower in soy-consuming countries. Because of evidence supporting the benefits of soy in lowering cholesterol, the Food and Drug Administration has approved a nutrition health claim on soy-containing food products stating that ¡°foods rich in soy protein as part of a low-fat diet may help reduce the risk of heart disease.¡±
 Soybeans have been cultivated in China for almost 5000 years, and the dietary use of soy foods is well documented.
 Because of their exceptional protein content (35-38%), ease of production, and long-term storage characteristics, soybeans have been highly prized as a food source.
 The dietary use of soybeans is also widespread in China and other Asian countries.
 The per capita annual consumption of soybeans was 7.4 kg in China, and 10.5 kg in Indonesia in 1994.
 Traditional soy foods include soy in both fermented (eg. miso, shoyu and tempeh) and unfermented (eg. tofu and soymilk) forms.


  8.1).Soy proteins

 As a protein source, soybeans are relatively high in lysine but low in methionine and are therefore best combined with other protein sources to achieve nutritionally "complementary protein".
 Soybeans also contain protease inhibitors, which have demonstrated anticarcinogenic, anti-nutritional, and pancreas-enlarging effects in animals.
 The potential beneficial and adverse effects of these compounds and their occurrence in soybean extract will be discussed in the second part of this article.

 Description:

 In October, 1999, the Food and Drug Administration (FDA) approved labeling claims for dietary soy protein stating that it may reduce the risk of heart disease. This is the 11th health claim allowed by the FDA. The health claim that can be used on labels of products containing soy protein states: "Diets low in saturated fat and cholesterol that include 25 grams of soy protein a day may reduce the risk of heart disease." In order to carry the health claim, one serving of a product must contain at least 6.25 grams of soy protein and must also be low in total and saturated fat, cholesterol and sodium.
 This latest FDA health claim was based on animal studies, epidemiological studies and human studies demonstrating that diets high in soy protein and low in animal protein lead to decreased levels of total cholesterol, low-density lipoprotein (LDL) cholesterol and triglycerides. The mechanism of the lipid-lowering effect of soy protein remains unclear.
 Soy protein isolates have become popular items in the nutritional supplement marketplace. Most of these supplements also contain the soy isoflavones genistin, daidzin and glycitin.

 Actions and Pharmacology: Soy protein may have lipid-lowering, antiatherogenic, antioxidant, anticarcinogenic and antiosteoporotic activities.

 Mechanism of Action:

 Diets rich in soy protein have been found to reduce serum levels of total cholesterol, LDL-cholesterol, triglycerides and apolipoprotein B (apo B). The mechanism of the lipid-lowering activity of soy protein is unclear. There are a few possible explanations. Soy protein is much richer in L-arginine than is animal protein, which is richer in L-lysine. Some animal studies indicate that dietary increases in L-arginine are accompanied by decreases in cholesterol levels. Further, some studies have demonstrated that, under certain conditions, e.g., hypercholesterolemia, high intakes of L-arginine could enhance endothelial-dependent vasodilation and nitric oxide or NO production (see L-Arginine). This could contribute to the possible antiatherogenic activity of soy protein.
 The soy isoflavones may also contribute to the lipid-lowering activity of soy protein as well as its antiatherogenic activity. Most soy protein products contain the isoflavones genistin, daidzin and glycitin, which have weak estrogenic effects and also may have antiestrogenic activity (see Soy Isoflavones). Oral estrogens have been shown to decrease total cholesterol and LDL-cholesterol. The soy isoflavones may have similar actions.
 Interestingly, a few studies have shown that when the isoflavones are removed from the soy protein, the protein itself has little hypocholesterolemic activity. Soy isoflavones themselves do not have the same hypocholesterolemic activity as the combination of soy protein and soy isoflavones. There are probably synergistic effects of these substances that are not understood at this time.
 There are also other substances associated with soy protein, including saponins, trypsin inhibitor and bioactive peptides, which may also contribute to the lipid-lowering activity of soy protein. The soy isoflavones are antioxidants, and their antioxidant activity may contribute to the possible anti-atherogenic effect of soy protein.
 The antioxidant, anticarcinogenic and antiosteoporotic activities of soy protein are probably due, in large part, to the soy isoflavones (see Soy Isoflavones). Soy protein has been found to reduce intestinal mucosa polyamine levels in rats, which may be another anticarcinogenic mechanism. Also, a bioactive peptide has recently been isolated from soybeans and has been found to have potent antimitotic activity.


 Pharmacokinetics: The digestion, absorption, distribution and metabolism of soy protein occurs by normal physiological processes. See Soy Isoflavones, Genistin, Daidzin and Glycitin for the pharmacokinetics of these substances.

 Indications and Usage: The FDA has allowed the following health claim for soy protein: "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." The isoflavone constituents of soy protein may confer some additional benefits. See Soy Isoflavones.

 Research Summary:

 The FDA-approved health claim~see Indications above~that soy protein, in adequate amounts, may help protect against heart disease is based upon numerous in vitro, animal, epidemiological and human studies. Evidence has accumulated over many decades showing that soy protein, but not animal protein, has significant cholesterol-lowering properties in animal studies.
 In a meta-analysis of clinical studies, most of them well-controlled, investigators concluded that soy protein significantly lowered serum concentrations of total cholesterol, LDL-cholesterol and triglycerides without significantly altering HDL-cholesterol concentrations.
 Since the meta-analysis cited above was conducted, other clinical research has continued to confirm the lipid-lowering ability of soy protein. Recently it was demonstrated that administration for six weeks of as little as 20 grams of soy protein per day, in place of animal protein, achieved significant reductions of non-HDL-cholesterol and apolipoprotein (apo) B in moderately hypercholesterolemic men.

 Contraindications,Precautions,Adverse Reactions: Soy protein supplements are contraindicated in those who are hypersensitive to any component of a soy protein-containing product.

 Precautions:

 Pregnant women and nursing mothers should avoid the use of soy protein supplements pending long-term safety studies or unless these supplements are recommended by their physicians.
 Women with estrogen receptor-positive tumors should exercise caution in the use of soy protein supplements and should only use them if they are recommended and monitored by their physicians.


 Nutritional Supplements and Foods: Soy contains phytic acid, which may bind with certain minerals, such as calcium, magnesium, manganese, zinc, copper and iron, reducing their availability.

 Dosage and Administration:

 There are several soy protein supplements available. Typically the soy protein supplements contain soy isoflavones. Dosage is variable.
 A total intake of 25 to 50 grams of soy protein and 50 milligrams of soy isoflavones daily may have cardiovascular and other health benefits. This can come from nutritional intake, as well as supplemental intake.


  8.2).Soy carbohydrates:

 Whole soybeans contain about 35% carbohydrate on a dry weight basis, including polysaccharides and the oligosaccharides stachyose and raffinose.
 Because humans lack digestive enzymes capable of hydrolysing the galactosidic linkages of stachyose and raffinose to simple sugars, these compounds are metabolised by intestinal microorganisms with the production of gas as a result.

  8.3).Soy lipids and phytosterols

 Soybeans also contain about 20% lipids, of which about 80% consist of unsaturated fatty acids.
 The major component of crude soybean oil is the omega-6 fatty acid linoleic acid (about 50%), with about 23% oleic acid, 11% palmitic acid, and 7% of the omega-3 fatty acid, linolenic acid.
 Soy is also a major dietary source of phytosterols, in particular b-sitosterol.
 Dietary phytosterol intake varies greatly between populations; the typical western diet provides about 80 mg per day, compared with vegetarian diets, which typically provide about 400 and 345 mg per day, respectively.
 Phytosterols are not absorbed to any significant degree, but inhibit the absorption of cholesterol from the digestive tract.


  8.4).Soy phytoestrogens

 Soybeans and soy foods are major sources of dietary phytoestrogens.
 The main group of phytoestrogens in soybeans is the isoflavones. The coumestan, coumestrol, occurs in small amounts in the beans (but in large amounts in soybean sprouts).
 In soy and other plants, isoflavones occur principally in the form of glycosides.
 The principal isoflavone glycosides in soy are genistin and daidzin; the corresponding aglycones are known as genistein and daidzein. Soybeans contain approximately three times as much genistin as daidzin.
 Glycitein 7-O-b-glucoside is a third isoflavone glycoside in soy. It is present in soybeans in smaller amounts than daidzin.
 Isoflavones appear to play several different roles in plant physiology. Some isoflavones, at least, act as antimicrobial defence compounds.
 The major soybean isoflavones, genistein and daidzein, are inducers of nodulation genes in the nitrogen fixing bacterium Bradyrhizobium, which forms nodules on soybean roots.
 However, it is the biological activity of isoflavones in mammals that has caused most excitement in recent years.


  8.5).What are phytoestrogens?

 Phytoestrogens are plant compounds that can have a variety of biological effects in humans, including oestrogenic effects under certain circumstances.
 The hormonal effects of phytoestrogens are due to a degree of structural similarity between these compounds and the human oestrogen, 17b-oestradiol.
 Phytoestrogens are not identical to human hormones, nor are they converted to human hormones in the body. The structural requirements for oestrogenic activity of phytoestrogens include a hydroxyl group in the same position as the hydroxyl group on the benzene ring in oestradiol.
 Oestrogen binding activity is further facilitated by the presence of a second hydroxyl group in the opposite end of the molecule.

 Oestrogenic and anti-oestrogenic activity:

 The generation of oestrogenic effect depends on the activation of specific receptors, subsequently leading to gene expression and modifications in cellular response.
 Phytoestrogens have an affinity for oestrogen receptors and have been shown to stimulate transcription activity of human oestrogen receptors.
 Compared with the human hormone oestradiol, phytoestrogens have very weak oestrogenic effects, typically ranging from 1/500 to 1/1000 of the activity of 17b-oestradiol.

 Soy and osteoporosis:

 The incidence of osteoporosis in this country is increasing as the population ages, leading to more hip fractures, pain, disability and death. One commonly recommended treatment is hormone replacement therapy for women at menopause. However, many women choose not to use hormone replacement because of the potential for side effects such as increased risk for breast cancer and leg thrombosis. Asian populations with a high soy intake have a substantially lower incidence of osteoporosis, suggesting that increasing our soy intake may be a beneficial alternative to hormone replacement therapy. Soy isoflavones are phyto-estrogens and may bind to estrogen receptors to maintain bone integrity after menopause without the detrimental side effects seen with hormone replacement treatments. Ovariectomized rats are being used as a model for postmenopausal women to study the potential of soy protein for maintaining bone mineral.
 Several studies in the LSU AgCenter¡¯s School of Human Ecology have confirmed that soy protein containing natural soy isoflavones can reduce the vertebral bone loss that normally occurs in ovariectomized rats. This research has shown that the protective effect of soy is dose responsive to the level of soy protein in the diet and is most beneficial when soy is part of a low-fat diet. In the most recent soy study, ovariectomized rats were fed a low-fat diet with 5 percent, 10 percent or 15 percent soy protein and compared to casein-fed rats with and without ovariectomy. The density of the vertebrae was measured at the end of the study. The benefits of soy protein on vertebral bone density were clearly seen in 10 percent and 15 percent soy fed rats. As the level of soy protein increased in the diets from 5 percent to 10 percent to 15 percent, the vertebral bone mineral density increased by 3 percent, 15 percent and 18 percent respectively, when compared to the ovariectomized control rats. This confirms the benefits of soy in reducing bone loss and osteoporosis.


  8.6).Soy saponins

 Soybeans contain significant amounts of saponins, about 5% of dry weight.
 Soy saponins have cholesterol-lowering properties and are also likely to facilitate the absorption of isoflavones from the gut.
 Saponins may also enhance immunity and provide a variety of anti-cancer activities.
 For example, soy saponins inhibit DNA synthesis in tumour cells and decrease the growth of human epidermoid and cervical carcinoma cells in vitro.
 Soy saponins also inhibit the expression of the Epstein-Barr viral genome.

  8.7).Soy Isoflavones:

 Soy contains many phytochemicals, and scientists are just now identifying the roles they may play in human health. Among these phytochemicals are the isoflavones:genistein, daidzein and glycitein,which may act as estrogen analogs in the body, affecting cells that contain estrogen receptors. LSU AgCenter researchers are studying the purification and characterization of soy isoflavones.
 The chemical structural differences of soy isoflavones may result in variable bioavailability in biological systems. The structures of soy isoflavones are not consistent during routine food processing. Factors induced in the food processing, such as enzymes in raw soy flour, heating and additives, can affect the stability of soy isoflavones. The isoflavones genistein, daidzein and glycitein, as found in soy foods, are usually bound to a glucose molecule forming the glucosides¡ªgenistin, daidzin and glycitin. In LSU AgCenter research, high purity genistin, daidzin and glycitin were prepared from soy flour and observed for their stability during heating. The results are useful in understanding the thermal stability of soy isoflavones. Overall, the stability of daidzein was found to be higher than that of glycitein or genistein.
 Many reports have indicated that soy isoflavones lower plasma cholesterol and may reduce the risk of cancer. The detailed mechanism for this capability is not fully understood. Oxidation products of cholesterol are harmful to many cells in the vascular system, which contribute to plaque formation and cancers. Because soy isoflavones contain phenolic groups, they may possess antioxidation properties that offer protection against oxidation of cholesterol and oxidative damage to blood vessel cells. In LSU AgCenter research, both genistein and daidzein demonstrated significant antioxidant activity in the inhibition of cholesterol oxidation. Since soy contains both genistein and daidzein, the combined antioxidant benefits of both isoflavones could be important in reducing oxidative damage to body tissues.


  8.7).Relative oestrogenic activity of phytoestrogens, precursors and metabolites in human cell culture bioassays, compared with oestradiol.

 Oestradiol 100.0
 Coumestrol 0.202
 Genistein 0.084
 Equol 0.061
 Daidzein 0.013
 Biochanin A <0.006
 Formononetin <0.0006
 Phytoestrogens have been shown to produce both oestrogenic and anti-oestrogenic responses. The current view is that phytoestrogens have mild oestrogenic activity when endogenous oestrogen levels are very low, ie post-menopause, while they have an anti-oestrogenic activity when endogenous oestrogen levels are high.
 This dual activity results because phytoestrogens, while competing with endogenous oestrogen for receptors, elicit only a very weak effect compared with the real hormone.
 Hence when oestrogen levels are high, phytoestrogens will occupy receptors that would otherwise have been occupied by oestradiol, resulting in a reduced oestrogenic response.
 When oestrogen levels are very low, however, phytoestrogens will occupy many receptors that would otherwise have remained unoccupied, resulting in a weak oestrogenic response.
 In summary, soybeans are a powerful functional food that contains phytochemicals that can reduce the risk of chronic diseases. Work at the LSU AgCenter has focused on purifying and describing the characteristics of the active components of soybeans that can benefit health. Researchers are continuing to study soy products and the isolation of active components that can benefit all of us. Throughout history, people living in Asia have relied heavily on soybean products to prevent or fight disease. It is time for the western world to learn how to use soybeans effectively in our diets to maintain a healthier life.


  Scientific References:

  1.Old ancient soybean,Soy and the dissemination,cultivation...