Old ancient soybean,Soy and the dissemination,cultivation.

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Soy Components:8.1).Soy proteins.

Soy Bean Extract INCI Name Glycine Soja Extract CAS 84776-91-0 Soy isoflavones Genistein CAS 446-72-0 Daidzein CAS 486-66-8 Glycine max L extract photo picture image 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.

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Reference:

citations1.Old ancient soybean,Soy and the dissemination,cultivation.

last edit date:5th,June.2009.