encyclopedia

Soybean

Scientific Names:
Glycine max (L.) Merrill [Fam. Fabaceae]

Forms:
GMO (Genetically Modified Organism) free soybeans, soy powder, soybean sprouts, tofu, soymilk, soy protein, roasted soy nuts, miso, tempeh or soy extracts

Traditional Usage:
– Antioxidant
– Anti-thrombosis
– Cellular Regeneration
– Cleansing
– Detoxification
– Hip Fracture Prevention
– Hot Flashes
– Lowering LDL Cholesterol
– Lowering Triglycerides
– Menopausal Problems
– Osteoporosis Prevention
– Vascular Disorders

Overview:
Soybean, Glycine max, is a legume in the plant family, Fabaceae. Soybean use was first recorded by Chinese Emperor Cheng-Nung in 2838 B.C. Soy foods, including sprouts, tofu, soy milk, soy protein, miso and tempeh, are known to have many health benefits stemming from isoflavonoid-type phytoestrogens, saponins, phytosterols and protein. Scientific studies indicate that phytoestrogens act as weak dietary estrogens, similar to the anti-estrogenic drugs Tamoxifen and Raloxifene, and prevent the development of abnormal growths in men and women. The low incidence of abnormal growths in Asian populations is often attributed to their phytoestrogen-rich diet. The average dietary isoflavone intake of the Korean population is estimated as 15 mg daily from genistein, daidzein and glycitein. In China and Singapore, only 14% of women experience hot flashes during menopause, compared to 70-80% in North America and Europe, attributed to the benefits of soy phytoestrogens. An Italian study with 104 postmenopausal women found that daily consumption of 60g soy protein led to a 45% reduction in moderate to severe hot flashes over a 12-week period compared to only a 30% reduction with placebo. Soy also improves bone health, prevents osteoporosis and hip fractures and reduces cholesterol levels. A meta-analysis of 29 placebo controlled studies found that people who consumed 31 to 47g of soy protein daily had a 9% reduction of total blood cholesterol, a 13% reduction of LDL cholesterol and an 11% reduction in triglycerides. The U.S. FDA has concluded that soy protein included in a diet low in saturated fat and cholesterol may reduce the risk of vascular disease by lowering blood cholesterol levels. Scientific studies show that 25 grams of soy protein is needed daily to show a significant cholesterol-lowering effect. A food must contain at least 6.25 grams of soy protein per serving to make the claim.

Active Ingredients:
Soybeans contain: Isoflavones including genistein, daidzein and glycitein, saponins, phytosterols and protein. The isoflavone and protein content of common soy foods is as follows: tempeh (1/2 cup) 60mg isoflavones and 18g protein; miso (1/3 cup) – isoflavones and 12g protein; firm tofu (1/2 cup) 38mg isoflavones and 14g protein; soymilk (1 cup) 20mg isoflavones and 9g protein; roasted soynuts (1/2 cup) 167mg isoflavones and -protein; toasted soy flour (1/2 cup) 88mg isoflavones and 16g protein; soy protein concentrate (4 oz) – isoflavones and 58g protein; soy protein isolate (4 oz) – isoflavones and 80g protein. (Dashes signify that no data was available). Soybean Sprout nutrients per 100g (proximates): Water 69.0%; Protein 13.1g; Total lipid (fat) 6.7g/100g; Carbohydrate, by difference 9.6g; Fiber, total dietary 1.1g; Ash 1.6g; Minerals (per 100g): Calcium, 67mg; Iron, 2.1mg; Magnesium, 72mg; Phosphorus, 164mg; Potassium, 484mg; Sodium, 14mg; Zinc, 1.2mg; Copper, 0.4mg; Manganese, 0.7mg; Selenium, 0.6mcg. Vitamins: Vitamin C, 15.3mg; Thiamin 0.34mg; Riboflavin 0.1 mg; Niacin 1.1mg; Pantothenic acid 0.9mg; Vitamin B-6 0.2; Folate, 172mcg; Vitamin B-12 0.00mcg; Vitamin A, 11 IU; Vitamin A, RE 1mcg. Lipids: Fatty acids, total saturated 0.9%; Fatty acids, total monounsaturated 1.5%; Fatty acids, total polyunsaturated 3.8%; Omega-6 Essential Fatty Acid (EFA) (18:2 undifferentiated) 3.3g; Omega-3 EFA (18:3 undifferentiated) 0.4g; Cholesterol 0.0. Amino acids: Tryptophan 0.16g; Threonine 0.5g; Isoleucine 0.6g; Leucine 0.9g; Lysine 0.8g; Methionine 0.14g; Cystine 0.16g; Phenylalanine 0.6g; Tyrosine 0.5g; Valine 0.6g; Arginine 0.9g; Histidine 0.35g; Alanine 0.55g; Aspartic acid 1.8g; Glutamic acid 2.0g; Glycine 0.5g; Proline 0.7g; and Serine 0.6g. [Information taken from The National Agriculture Library’s USDA Nutrient Database for Standard Reference, Release 14 (July 2001)]

Suggested Amount:
The FDA approved dosage for soy protein for lowering cholesterol and improving vascular health is 25g or more per day. The recommended dosage of soy isoflavones for alleviating menopausal symptoms is 50-75mg per day. The recommended dosage of soy isoflavones for osteoporosis prevention is 55-90mg isoflavones daily. One case report of a successful treatment of abnormal growth of the prostate with phytoestrogens from red clover, a legume with similar chemistry to soy, used a dosage of 160mg daily for seven days upon which prominent apoptosis was observed without any negative side effects. [The red clover extract mentioned in the prostate study was standardized for its content of genistein, daidzein, formomonetin and biochanin A. Intake of the isoflavone equol (formed within the gut by metabolism of daidzein by beneficial intestinal microflora) and the mammalian lignan enterolactone (likewise formed from flaxseed lignans within the gut) are linked with producing the greatest reduction in risk for abnormal growths. It is noted by researchers that not all people are able to produce equol from daidzein].

Drug Interactions:
None known

Contraindications:
None known

Side Effects:
None known

References:

Anderson JW, Johnstone BM, Cook-Newell ME. 1995. Meta-analysis of the effects of soy protein intake on serum lipids. New England J Med 333: 276-282.

Kim J, Kwon C. 2001. Estimated dietary isoflavone intake of Korean population based on National Nutrition Survey. Nutr Res. 2001 Jul; 21(7): 947-953.

McCaleb RS, Leigh E, Morien K. 2000. Soy in The Encyclopedia of Popular Herbs. Publ. by Prima Publishing, 3000 Lava Ridge Court, Roseville, CA 95661. Pp. 350-364.

Messina M. 1995. Modern applications for an ancient bean: soybeans and the prevention and treatment of chronic disease. Journal of Nutrition 125: 567S-569S.

Morton MS, Wilcox G, Wahlqvist ML, Griffiths K. 1994. Determination of lignans and isoflavonoids in human female plasma following dietary supplementation. J Endocrinol. 1994 Aug; 142(2): 251-9.