Chinese having a regular consumption of soybeans and/or tofu have only one-half as much cancer of the stomach, colon, breast and lung compared with those Chinese who rarely consume soy or soy products. Soybeans contain fairly high levels of several compounds with demonstrated anti-cancer activity, including a high content of isoflavonoids, such as genistein. These isoflavonoids have been shown to inhibit the growth of both human breast and prostate cancer cells. In addition, regular use of soy protein (soybeans, tofu, soy nuts, soy beverage) can lower blood cholesterol and triglyceride levels by 10 to 15 percent, especially in persons with elevated lipid levels.

Eating Soy Bean to Fight Cancer [source: Medicinal Food News, Vol 2, 1998, Issue 5
For many of us the only time soy got into our diet was when we used salad dressing made from soybean oil. More and more people are eating soybeans as they learn about the many benefits of this legume. Soybeans are rich in plant phytoestrogen hormones called isoflavones. These isoflavones are similar in structure to the estrogens in the human body and so adding soybeans to the diet may be a way of increasing estrogen levels. That at least is the reasoning behind the interest in soybeans by women approaching menopause. The observation that the Japanese and Chinese have low incidences of breast, colon and prostate cancer has led researchers to investigate other components of soybean that may be beneficial to health. In an article published recently in the Journal of the National Cancer Institute laboratory work has pointed at a compound called genistein as a possible anti-cancer agent in soybean. Genistein appears to affect the metabolism of cancer cells by weakening their defences against anti-cancer drugs and treatments such as chemotherapy and radiation treatment. Cancer cells have developed enzyme systems to produce protective proteins that allow the cancer to resist treatment. Genistein appears to be able to interfere at the production of these protective proteins, thereby reducing the ability of cancer cells to survive and grow. So there may be more than one reason why you would want to increase the amount of soybean in your diet. It is the protein part that contains the genistein; adding more soybean oil to your salad won't help.

Soy Products, Breast Cancer, and Other Diseases
The NBC show, "Dateline" of June 9, reported the overall benefits of consumption of soy products. One of the highlights of the article was the connection of increased soy consumption and protective effects against breast cancer. My work explains these beneficial effects of soy consumption. Soy increases production of the hormone, dehydroepiandrosterone (DHEA).
I suggest DHEA is necessary for growth and development of all tissues and adult tissues require DHEA for proper maintenance. A subordinate hypothesis of this is that the stability of cells depend upon DHEA. This eventually resulted in my explanation of cancer as a result of reduced DHEA. That is, reduced DHEA may trigger oncogene (genes of cancer) activation. DHEA begins to decline after age 20-25, reaching very low levels in old age. I suggest this is why cancer incidence increases with age. Measurable levels of DHEA are reduced in women with breast cancer, and this reduction occurs as early as nine years prior to diagnosis (Geriatrics 1982; 37: 157). A number of studies demonstrate that treatment with DHEA provides a protective effect against breast cancer. That is, raising DHEA reduces the incidence of breast cancer. One citation that reports this also found beneficial effects of DHEA in other areas important to aging women. "These data show that DHEA exerts a stimulatory effect on bone mass and an inhibitory effect on serum triglycerides, as well as a protective effect on the development of mammary carcinoma induced by DMBA in he rat. Such data suggest that while decreasing the risk of breast cancer, DHEA replacement therapy could also exert beneficial effects on the bond and lipid metabolism in women receiving DHEA replacement therapy." (Endocrinol. 1997; 138: 3387). Therefore, increasing DHEA reduces breast cancer incidence. A connection of soy consumption, reduced breast cancer, and increased levels of DHEA sulfate (the serum precursor of DHEA) was reported in 1995. "There is also evidence that soy products may affect risk factors for cancer, such as endogenous hormone levels. Preliminary data from our group indicate that young Adventist women who are vegetarians with high soy intake and a lower risk of breast cancer may have higher levels of an adrenal androgen, dehydroepiandrosterone sulfate." (J. Nutr. 1995; 125(3 Suppl): 709S-712S). It was suggested on "Dateline" that the increase in breast cancer in Japanese women, who move to the U.S., may be a result of reduced soy consumption in this country.
A number of studies have reported general benefits of DHEA treatment in aging men and women. "DHEA in appropriate replacement doses appears to have remedial effects with respect to its ability to induce an anabolic growth factor, increase muscle strength and lean body mass, activate immune function, and enhance quality of life in aging men and women, with no significant adverse effects." (Ann. N. Y. Acad. Sci. 1995; 774: 128) The "Dateline" article included a discussion with an investigator who suggested many beneficial effects of soy consumption in many diseases. I suggest these, and the protective effect of soy on breast cancer, are the results of increases in DHEA. It is the increase in DHEA that may produce the real beneficial effects.

Copyright © 1997 by James Michael Howard.

Soy Products, Ginseng May Lower Breast-Cancer Risk
[Medical Tribune: Family Physician Edition 38(20): 1997. © 1997 Jobson Healthcare Group]

SAN ANTONIO--Tofu and other soy-based foods--and possibly even the herb ginseng--may help women stave off breast cancer, according to preliminary research presented here last month at the annual meeting of the American Osteopathic Association.
In a laboratory study of human breast-cancer cells, high amounts of isoflavones--dietary components found in soy-based products--stunted the growth of cancerous cells by as much as 30%, reported Donna Dixon Shanies, Ph.D., an assistant professor of biochemistry and genetics at the New York College of Osteopathic Medicine in Old Westbury, N.Y.
In a second laboratory study, Dr. Shanies found that traditional Chinese herbal remedies including ginseng and vitex berry extract also inhibited the growth of human breast-cancer cells.
Because they are loaded with phytoestrogens, isoflavones may help prevent breast cancer by reducing levels of natural estrogen in the body, she explained. Or isoflavones may have antioxidant properties that inhibit tumor development. "Phytoestrogens may in the future prove to be promising agents used to reduce the risk of breast cancer and other hormone-dependent cancers, such as prostate cancer," Dr. Shanies said.
Although there are no recommendations concerning how much soy individuals should include in their diets, she said, "it would be prudent for women to try to eat more soy products."
Dr. Shanies and colleagues tested the effects of three major isoflavones--biochanin A, daidzein and genistein--on human breast-cancer cells. They also measured the effects of ginseng, black cohosh root, dang gui root, hops flower, vitex berry and shiu chu ginseng root on breast-cancer cell lines.
Calling the new research "a promising first step," Richard J. Cenedella, Ph.D., chairman of the department of biochemistry at the Kirksville College of Osteopathic Medicine in Kirksville, Mo., said the findings add a new dimension to what is understood about the link between diet and breast cancer.
"We have always known that there are beneficial effects of a low-fat diet [on breast-cancer risk], and concentrations of trace plant hormones found in certain foods may play a role in the reduced risk," Dr. Cenedella said. --D.M.

Phytoestrogens of Soybeans: An Alternative Approach to Traditional HRT ?
Presented at "The Health Impact of Soy Protein Symposium"
UCLA Center for Human Nutrition, January 20, 1998
by
Thomas B. Clarkson, D.V.M.
Professor of Comparative Medicine at the Wake Forest University School of Medicine

Traditional postmenopausal hormone replacement therapy (HRT) preserves bone density, reduces the risk for coronary heart disease and may sustain cognitive function with aging. Despite these health benefits compliance is poor (about 10 percent of women older than 55 years). Poor compliance relates primarily to fear of breast cancer and the need for co-administration of progestin to those with uteri. We have focused on the phytoestrogens (genistein and daidzein) from soybeans as potential alternatives to traditional HRT - particularly because they may be breast cancer protective and are antiestrogens for the endometrium thus obviating the need for a progestin.
Cardioprotective Effects. We have compared soy phytoestrogens (SBEs) and conjugated equine estrogens (CEE) administered to surgically postmenopausal monkeys to their effects on plasma lipoproteins concentrations. SBEs increased HDL cholesterol and Apo A1 more than CEE and LDL cholesterol was decreased more by SBEs. CEE, but not SBEs, resulted in hypertriglyceridemia. Data on atherosclerosis of postmenopausal female monkeys is incomplete but both soy phytoestrogens and CEE inhibit the progression of atherosclerosis. Soy phytoestrogens, like estradiol, enable coronary arteries to dilate in response to acetylcholine.
Breast and Endometrial Effects. We have compared the effects of SBEs and CEE on the breast and uterus of postmenopausal monkeys. SBEs are not estrogen agonist for either breast or endometrium. Moreover, they are estrogen antagonist at these sites, preventing the usual proliferative changes induced by estradiol.
Brain Effects. Soy phytoestrogen's effect on brain biomarkers of cognition (brain derived-neurotrophic factor and acetylcholine production) are comparable to those of estradiol.

UCLA Center for Human Nutrition
900 Veteran Avenue
Los Angeles, CA 90095-1742

Soy Protein Isoflavone Effects on Breast Tissue
Presented at "The Health Impact of Soy Protein Symposium"
UCLA Center for Human Nutrition, January 20, 1998
by
Stephen Barnes, Ph.D.
Professor of Pharmacology & Toxicology and Biochemistry & Molecular Genetics in the School of Medicine at the University of Alabama at Birmingham

Isoflavones, so abundant in soy, have been shown to have biochemical and biological effects in a variety of in vitro and animal models. These effects are not only based on the estrogenic properties of isoflavones, but also their role as protein tyrosine kinase inhibitors, regulators of gene transcription, modulators of membrane transporters, and as antioxidants. Predicting the outcome of the effects of isoflavone-rich diets, such as those based on soy, on chronic diseases (cancer and heart disease) should not be based on one of these mechanisms alone. For instance, the prevention of osteoporosis by isoflavones (an estrogenic effect) is in contrast with epidemiological and laboratory data which suggest soy and isoflavones prevent cancer. However, the recent discovery of new estrogen receptor (ERP) which selectively binds the isoflavone genistein is providing new rationales to explain the estrogen paradox. ERP shows a different tissue distribution from the classical estrogen receptor, being abundant in bone, the brain, cardiovascular system, genitourinary system, lungs and prostate, but not in the breast. This allows genistein to have beneficial effects at these targets without increasing the risk of breast cancer. Thus the isoflavones may be naturally occurring forms of an important new class of drugs called selective estrogen receptor modulators (SERMs), being developed for the treatment of the postmenopausat disease in women.

UCLA Center for Human Nutrition
900 Veteran Avenue
Los Angeles, CA 90095-1742
More Abstracts
Copyright 1998
Indiana Soybean Board

Cancer killer
A hormone in soya beans starves tumour cells to death
[New Scientist 14 mar 98]

BIOCHEMISTS in the US have worked out how a key ingredient in soya beans thwarts cancer. Thev have shown that genistein, a plant oestrogen, plays a pivotal role in suppressing the growth of cancerous cells. Asian diets high in soya have been linked with low incidence of cancers, particularly breast, colon and prostate cancers. This link has been reinforced by evidence that when Asians migrate to the US and abandon the high-soya diet, their risk of developing these cancers increases. Amy Lee of the University of Southern California in Los Angeles has discovered that genistein is a key factor in this. It works by weakening cancer cells' response to the stresses that usually impel them to grow faster. "When a cancer cell is growing at full blast, the cells soon run out of oxygen and glucose that are normally supplied in blood," savs Lee. To compensate, they send out a chemical SOS which triggers formation of new vessels to nourish the tumour, a process called angiogenesis.
In earlier experiments on tissue cultures, Lee and others proved that genistein can blunt the response of cancer cells to stress. Now, they know the exact mechanism. She and her colleague Yanhong Zhou have shown that genistein blocks the action of a transcription factor known as CCAAT binding factor. This protein normally binds to an important genetic "motif" in DNA and triggers the stress genes. Genistein adds phosphorus to the binding factor, neutral- ising it before the snvitch is tripped, so the cancer cell starves, withers and dies (journal of the National Cancer Institute, vol 90, p 381). "This is preliminary evidence, but genis- tein really stands out as the ingredient that's most active in stopping cancer growth and angiogenesis," says Lee. Crucially, the researchers found that genistein has no effect on normal, healthy cells which are not dividing rapidly like cancer cells. "It doesn't shut off the normal synthesis of this protein in healthy cells," says Lee. Andy Coghlan