Soy has been a main food in Asian countries for many years. This is because they are very nutritious: they contain about 36% protein, 18% fat, 30% carbohydrates, isoflavones and a lot of minerals and vitamins. All eight essentials amino acids are present in the soybean, which makes the soybean protein a complete protein.
What is Soy Isoflavones?
Soy isoflavone distillate or concentrate is extracted from the seeds or beans of the soy herb that affect a wide-variety of body systems.Soy isoflavones belong to a class of plant-based compounds known as phytoestrogens, so-called because they are similar in chemical structure and function to the female sex hormone estrogen.Soybean encloses several elements or compounds such as isoflavones and lecithin that are therapeutically very valuable.They have been implicated in both reductions and increases of breast cancer risk, and generally are good at cardioprotection from reducing lipoprotein levels and are seen as good for bone health in the aging as well.
Part of plant used
Soybean Isoflavones 10%-40%
Soy is a unique dietary source of the isoflavones, such as genistein and daidzein. It has been part of the Southeast Asian diet for nearly five millennia, whereas consumption of soy in the Western World has been limited until the 20th century. Heavy consumption of soy in Southeast Asian people is associated with reduction in the rates of certain cancers and cardiovascular disease, and the troublesome side effects that may accompany with menopause. Recent experimental evidence suggests that isoflavones in soy, which has been scientifically analyzed since the 80's, are responsible for the beneficial effects.
The hypothesis that soybean isoflavones may help relieve menopausal symptoms (such as hot flashes, emotional disturbances and compromised sexual activity) has been confirmed by recent scientific studies. Furthermore, soybean isoflavones significantly decrease the rates of breast cancer, which is thought to be relevant to their effects as phytoestrogens. Studies also point out that high consumption of soy isoflavones in the diet are implicated in inhibiting the growth of prostate cancer cells, those who eat a low-fat diet, but rich in soy proteins, have a lower incidence of prostate cancer.
Lower Cancer Risk In Men and Women
Soy Isoflavones are important new elements in the prevention and potential treatment of cancer. Soy isoflavones also have antioxidant properties, and like other antioxidants, they can reduce the long-term risk of cancer by preventing free radical damage to DNA.
Eaten for 5,000 years in Asia, soy appears to reduce the risk of breast cancer and other reproductive organ cancers. In recent years, epidemiologists have focused on soy foods as one of the major dietary differences between Asians and Americans. Asian women eating traditional high-soy diets have a relatively low risk of breast cancer, but their risk increases when they move to the United States and adopt a Western diet.
Similarly, Asian men who eat high-soy diets have a low risk of invasive prostate cancer. The standard American diet has no phytoestrogens, says Susan Lark, M.D., who specializes in women's health issues in Los Altos, Calif. Of soy and other natural sources of phytoestrogens, she adds, you have to keep taking these foods to maintain their estrogen like benefits.(source: Nutrition Science News, September 1998.)
Additionally, in a group of Australian Caucasian women, those whose diets were included higher amounts of isoflavones and other phytoestrogens had a lowered incidence of breast cancer. (source: cancer: Principles and Practice of Oncology 3rd Edition, Philadelphia, JB Lippincott, 1989, pp 167-180.)
Isoflavones also reduce cancer risk by inhibiting the activity of tyrosine kinase, an enzyme that promotes cancer cell growth. (source: J Cellular Biochemistry, 1995;22S:181-7) Some researchers have shown that genistein is antiangiogenic, and as an antiangiogenic substance, it blocks the growth of blood vessels that tumors need to expand. (source: J Nutr 1995; 125:790S-7S.)
Use In Estrogen Replacement Therapy
The benefits of soy go beyond reducing long-term cancer risk. Recent studies have found that soy (in either isoflavones-rich protein or pure isoflavones supplements), can reduce menopausal hot flashes and increase bone density in women. Indeed, many menopausal and postmenopausal health problems may result from a lack of isoflavones in the typical American diet. (source: Nutrition Science News, September 1998)
Estrogens are essential for the female reproductive system, but they are also important for the bones, heart and possibly the brain. For women facing menopause (and the loss of estrogen), replacing estrogens is a major issue. Christine Conrad, co-author with Marcus Laux, N.D. of Natural Woman, Natural Menopause (HarperCollins, 1997), relates that soy isoflavones and other plant estrogens are effective hormone replacements after a hysterectomy. Other researchers have reported the isoflavones are also estrogenic enough to promote bone formation.
Lower Cholesterol and Reduce Heart Disease Risk
In addition to their estrogenic activity, soy isoflavones promote healthy cholesterol levels without lowering levels of the beneficial HDL cholesterol. Also, soy isoflavones may maintain normal vascular function. The Soy Connection Newsletter reports that "...even in people with normal cholesterol, soybean isoflavones may help to reduce heart disease risk." (Vol. 6, No. 2, Spring 1998)
1,Effects of Mammalian and Plant Estrogens on Mammary Glands and Uteri of Macaques
In a recent study of hormonal replacement therapy and its alternatives, adult, surgically postmenopausal female macaques (Macaca fascicularis) were treated continuously with either estradiol (E2), isoflavone-enriched soy isolate (SBE), or E2+SBE. Doses were equivalent on a caloric basis to 1 mg/woman/day for estradiol, and 148 mg/woman/day for soy isoflavones. After 6 months of replacement therapy, histopathologic, morphometric and immunohistochemical measurements of endometrium and mammary glands were done.
Increases in endometrial thickness, gland area, and epithelial proliferation were induced by E2 and E2+SBE. Morphometric changes were accompanied by increased epithelial Ki67 staining in the E2 treated group. The effects of E2 were partially antagonized by SBE (manifested as decreased Ki67 staining). Mammary gland proliferation was induced by E2 and E2+SBE, morphometric and immunohistochemical measures of proliferation were in agreement in both tissues. The effects of E2 were antagonized by SBE in the mammary gland. Nuclear estrogen receptor (ER) staining of both tissues showed no significant differences between E2, SBE, and SBE + E2 treated macaques. ER labeling was apparent in the SBE group. In the E2 and E2 + SBE treated animals there was an increase in the nuclear staining of progesterone receptor (PGR) of mammary tissue and endometrium. In the endometrium, we saw a decrease in the nuclear PGR staining: superficial glands SBE group: 2,4 +/- 7,59 compared to 21,5 +/- 28,00 % labeled cells control group.
Conclusion: In this primate model SBE treatment did not induce proliferation in endometrium and mammary tissue. The results indicate that SBE may have antiproliferative effects in the endometrium and mammary gland when given along with exogenous estrogen. (J.M. Ernst-Moritz-Arndt University, Greifswald, Germany, and Department of Comparative Medicine, Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, NC.)
2,Investigating protective effects of dietary isoflavones against UV irradiation in a hairless mouse model.
Hairless mice were orally administered with soy extract (500mg/Kg body Wt/d) containing isoflavones (30%) and were exposed to UV-irradiation three times a week over one month to afford a total dose of 600mJ/cm2. At the end of the study, it was measured the effects of isoflavones on skin appearance, collagen deposition and epidermal thickness in the UV-damaged mouse skin. In skin fibroblast culture, the effects of isoflavone on synthesis/degradation of collagen and metalloproteinases(MMPs) were determined. Results showed better skin appearance and less wrinkles in isoflavone treated group compared to UV-damaged, untreated group.
Soy isoflavones are very safe at a wide range of consumption. A small percentage of people allergic to soybeans should avoid consuming soy products. Consumption of soy isoflavones is not associated with any significant side effects aside from the mild gastrointestinal issues (bloating, flatulence). High dose intake of concentrated isoflavone extracts are safe at levels up to at 300 mg per day (the estimated amount contained in the average Japanese diet). Since the long term effects of isolated isoflavone supplements is unknown and the potential for pro-estrogenic effects may exist for mega-dose isoflavone consumption, it is prudent to keep total isoflavone intake close to those levels found in dietary amounts.
1.For heart health, 30-50 mg of soy isoflavones per day is effective in reducing cholesterol and triglyceride levels.
2. For menopausal symptoms, 25-50 mg of soy isoflavones per day is effective in alleviating some of the symptoms associated with menopause (e.g. hot flashes). Do not exceed more than 200 mg per day.
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