| PDF[?] (Download) | IsoflavonesSoy (Glycine max) | | Date: March 12, 1999 | HC# 122482-152 |
Re:Health Role Development of Isoflavones from Soybeans
Barnes, Stephen. Evolution of the Health Benefits of Soy Isoflavones Proceedings of the Society for Experimental Biology and Medicine. :.
Soy is a major dietary source of the isoflavones genistein and daidzein, thought to confer health benefits. Though soy has been part of the Asian diet for several thousand years, the first recorded growth of soybeans in the West did not occur until the 18th century in botanical gardens in England and France. Ancient Chinese texts speak of the medicinal value of soy, although they favored the black soybean (kuroname) for medicinal purposes over the more familiar yellow bean grown in the United States. Modern beliefs about the health benefits of soy are the result of a collection of epidemiological, clinical and laboratory experiments suggesting that several agents in soy may help reduce the risk of certain diseases, such as heart disease and cancer. Isoflavones are one of the most promising groups of compounds found in soy that are believed to be related to its health benefits.
Soy and Cardiovascular Disease
In the 1970's, researchers began investigating the effect on blood cholesterol levels of switching from an animal-protein diet to a plant-protein diet. However, it wasn't until the 1995 publication of a meta-analysis of the research available that the scientific community was prepared to accept that soy was associated with a lowering of plasma cholesterol. It now appears that a soy-based diet provides protection form the risk of death from cardiovascular disease and may help explain the low incidence of this disease in China.
Soy and Cancer
Epidemiological studies show that the consumption of soy is associated with a lowered risk of leukemia as well as cancers of the breast, lung and prostate. Supportive evidence has been found in studies utilizing cultured human breast cancer cells, leukemia cells and prostate cancer cells, and cells from animals.
Soy and Menopausal Symptoms
As a woman approaches menopause there is an increased risk of osteoporosis. Estrogen replacement therapy, started early enough, can prevent this and other perimenopausal problems. However, the increased risk of endometrial cancer caused by estrogen therapy is a concern for some women. One drug currently being investigated as an alternative to estrogen replacement therapy, Ipriflavone, which has daidzein as one of its metabolites. In a recent study using rats, made surgically postmenopausal, researchers found that genistein, administered in the diet can significantly increased bone mass compared to controls.
Soy Infant Formula and Estrogenicity
Over the past 30 years soy protein has been used in infant formulas. The formulas were developed for infants who had digestion and diarrheal problems with cow's milk. Despite their apparent successful use over the years, a controversy has recently arisen over the possible effects of estrogenic isoflavonoids in soy on infants during a critical developmental stage. Isoflavones are found in the urine of young infants, but it isn't known what proportion of the ingested isoflavones in the diet is actually absorbed. The metabolism of soy isoflavones in infants needs to be elucidated.
Mechanism of Action of Genistein
The role of genistein as an estrogen is controversial. Depending on its concentration in the blood, it can have weak estrogenic effects and can stimulate cell growth or it can inhibit the proliferation of estrogen-dependent human breast cancer cells. A small pilot study found that genistein has an antiangiogenic effect in people suffering from hemorrhagic talengiectasia (HHT), a severe hereditary disorder that causes abnormal blood vessel development in the nose, lung and gastrointestinal tract. Severe nosebleeds are common. In two out of five subjects with HHT, who were treated with 40 grams a day of isolated soy protein, nosebleeds stopped completely. Another area of growing interest is the effect of genistein on inflammatory diseases. Recent observations of its antiinflammatory effects confirm observations made several thousand years ago in the Chinese medical literature. Moreover, genistein may also play a role in the prevention or treatment of autoimmune diseases. - Densie Webb, Ph.D
Enclosure: Copyright permission 1998, the Society for Experimental Biology and Medicine Bin #152 |