Phytoestrogens are hormone-like bioregulators that come from plants, without the harmful side effects related to some estrogens. Isoflavones are a class of phytoestrogens that are concentrated in soybeans, and also found in plants that humans generally don't eat, such as red clover and kudzu. The soy isoflavones genistein and daidzein are currently being investigated in clinical studies as protectants against chronic diseases such as hormone-dependent cancers (breast and prostate cancer), cardiovascular disease, and osteoporosis.1
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Genistein has raised concerns over its potential negative effects on immune function, brain function, and DNA repair. Daidzein doesn't share these negative effects, and is more effective than genistein at building bone and preventing cancer, in both men and women.
What is Daidzein?
It's an isoflavone found mostly in soybeans, legumes, and peas. Soy isoflavones are free radical scavengers (potent antioxidants) and are antiangiogenic (they interfere with unwanted blood vessel growth in disease states). They have been shown to have a beneficial effect on some types of cancer and bone health.
Daidzein is also found in Radix puerariae (RP), an herbal medicine made from kudzu root. RP has been used for centuries in traditional Chinese medicine for the treatment of a wide range of disorders, including alcoholism. It is thought that the antidipsotropic (anti-drinking) effect of RP is due to daidzein.2
Asians typically consume 15-50 mg per day of isoflavones, compared with the average consumption of approximately 1-2 mg. per day in the West.3 Interestingly, in countries like Japan where soy consumption is high, there is approximately an 80 percent lower incidence of prostate cancer than in the West.
In a study that followed Japanese men who immigrated to the United States and abandoned their traditional diets, it was found that within one generation, there was a four-fold to nine-fold increase of prostate cancer among them.4 But unfortunately, the main isoflavone in soy, genistein, actually seems to have undesirable toxic effects.
Offers prostate cancer protection
Researchers at the Division of Cellular Integrity, Rowett Research Institute, Aberdeen, UK investigated the effects of genistein and daidzein on human prostate tumor cells. Genistein caused DNA damage, while daidzein inhibited cell growth without causing DNA damage.5
Daidzein doesn't share genistein's toxic properties, and was shown to be very protective against prostate cancer in another study showing that peas dramatically reduce risk of prostate cancer. Peas contain a lot of daidzein, but no genistein.6
Daidzein may help prevent breast cancer
A recent study found that women who ingest daidzein may be better protected against breast cancer.7
Like men living in Asia with lower risk of prostate cancer than men living in the West, women living in Asia have a lower risk of breast cancer. This difference similarly disappears within a generation or two after Asian women emigrate to the West and alter their diet, which was originally high in soy isoflavones. A number of studies have reported a direct protective effect of soy isoflavones on breast cancer, in in vitro studies, laboratory animals and humans.8 A study at the University of Illinois, Chicago found that daidzein reduced breast tumor growth by 32% in laboratory rats.9
Helps prevent osteoporosis
It's a well known fact that one out of two women older than age 50 suffers an osteoporosis-related fracture during her lifetime. But osteoporosis is not restricted to women. Although, osteoporosis research of men remains inadequate, and a large number of men remain undiagnosed, it is estimated that osteoporosis affects about two million American men. Another three million men may be at risk due to decreased bone density.
One in eight men over age 50 will have an osteoporosis-related fracture in his lifetime. In fact, each year men suffer one third of all the hip fractures that occur, and one third of these men will not survive more than a year. In addition to hip fractures, men also experience painful and debilitating fractures of the spine, wrist, and other bones due to osteoporosis. Furthermore, older men suffer many more rib fractures than do elderly women.10
What causes osteoporosis?
In the human body, there is a constant process of breaking down and remaking of bones. Cross-cultural studies show that, throughout the world, most people lose bone mass as they age.11 After age 40 to 50, men lose 20 to 30 percent of their total bone mass, and women lose as much as 40 to 50 percent.12 Generally, though, the remaining bone is healthy and able to repair itself. This is considered normal aging. When the rate of bone breakdown exceeds that of bone being manufactured it can result in osteoporosis.
Daidzein stimulates bone formation and mineralization
Hormones play an important role in maintaining bone mass. Once women reach menopause and hormone levels decline, bone loss escalates. Rapid bone loss continues for about five years during menopause, and can reach three to four percent of total bone mass. This surge of bone loss eventually tapers off after a few years, and is about equal to the amount of bone loss in men of the same age. The loss of bone minerals continues throughout the rest of a person's life-which is one of the reasons there is a lot of excitement about research into daidzein's ability to help stimulate bone formation and mineralization, in the same way that hormones do.
Animal experiments, as well as bone tissue and bone cell culture investigations, have demonstrated daidzein's effect on bone metabolism. Also, daidzein has been shown to enhance bone formation, and help prevent and treat osteoporosis in elderly women.1314151617
How does daidzien work?
Although the mechanism of daidzein's anti-carcinogenic activity is unclear, its isoflavones are thought to produce a weak estrogenic effect-the lowest of the soy isoflavones-that protects against prostate and breast cancer. It also stimulates osteoblasts (new bone cells) in cell cultures, suggesting that it may be able to stimulate bone formation.
If you're concerned about bone health, or protecting yourself from prostate and breast cancer, try daidzein. Available for the first time as a supplement, it's safer than consuming gallons of soy milk, or pounds of tofu which contain genistein, the other isoflavone that has been shown to inhibit immune function, brain function, and DNA repair.
Daidzein is the safer soy isoflavone with numerous health benefits.
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This article is not intended to diagnose, treat, cure, or prevent any disease. Always consult with a physician before embarking on a dietary supplement program.
Wiseman H. The therapeutic potential of phytoestrogens. Expert Opin Investig Drugs. 2000 Aug;9(8):1829-40.
PDR health. "Daidzein" http://www.pdrhealth.com/drug_info/
USDA-Iowa State University Database on the Isoflavone Content of Foods, Release 1.3 2002. http://www.nal.usda.gov/fnic/foodcomp/Data/isoflav/isoflav.html
Vacherot F, Azzouz M, Gil-Diez-De-Medina S, Colombel M, De La Taille A, Lefrere Belda MA, Abbou CC, Raynaud JP, Chopin DK. "Induction of apoptosis and inhibition of cell proliferation by the lipido-sterolic extract of Serenoa repens (LSESr, Permixon in benign prostatic hyperplasia." Prostate 2000 Nov 1;45(3):259-66.
Mitchell JH, Duthie SJ, Collins AR. Effects of phytoestrogens on growth and DNA integrity in human prostate tumor cell lines: PC-3 and LNCaP. Nutr Cancer. 2000;38(2):223-8.
Bayne CW, Ross M, Donnelly F, Habib FK. "The selectivity and specificity of the actions of the lipido-sterolic extract of Serenoa repens (Permixon) on the prostate." J Urol 2000 Sep;164(3 Pt 1):876-81.
Atkinson C, Skor HE, Dawn Fitzgibbons E, Scholes D, Chen C, Wahala K, Schwartz SM, Lampe JW. Urinary equol excretion in relation to 2-hydroxyestrone and 16alpha-hydroxyestrone concentrations: an observational study of young to middle-aged women. J Steroid Biochem Mol Biol. 2003 Jul;86(1):71-7
Ying C, Hsu JT, Hung HC, Lin DH, Chen LF, Wang LK. Growth and cell cycle regulation by isoflavones in human breast carcinoma cells. Reprod Nutr Dev. 2002 Jan-Feb;42(1):55-64.
Constantinou AI, Lantvit D, Hawthorne M, Xu X, van Breemen RB, Pezzuto JM. Chemopreventive effects of soy protein and purified soy isoflavones on DMBA-induced mammary tumors in female Sprague-Dawley rats. Nutr Cancer. 2001;41(1-2):75-81.
Seeman, E., et al., "Risk Factors for Spinal Osteoporosis in Men,"Am J Med 75 1983: 977-983
Frost, H., "The Pathomechanics of Osteoporosis," Clin Orthop 200, 1985: 198-225
Fauci, Anthony S., et al. Harrison's Principles of Internal Medicine, Vol. 2. New York: McGraw-Hill, 1998.
"Isoflavones and calcified tissues" Usp Fiziol Nauk 2002 Apr-Jun;33(2):83-94
Picherit C, Coxam V, Bennetau-Pelissero C, Kati-Coulibaly S, Davicco MJ, Lebecque P, Barlet JP.Daidzein is more efficient than genistein in preventing ovariectomy-induced bone loss in rats. J Nutr 2000 Jul;130(7):1675-81
Gao YH, Yamaguchi M. Anabolic effect of daidzein on cortical bone in tissue culture: comparison with genistein effect. Mol Cell Biochem1999 Apr;194(1-2):93-7
Kritz-Silverstein D, Goodman-Gruen DL. Usual dietary isoflavone intake, bone mineral density, and bone metabolism in postmenopausal women. J Womens Health Gend Based Med 2002 Jan-Feb;11(1):69-78
Ishida H, et al. Preventive effects of the plant isoflavones, daidzein and genistein, on bone loss in ovariectomized rats fed a calcium-deficient diet. Biol Pharm Bull 1998;21:62-6.