Reprinted with permission of Energy Times Magazine February 97
- Genistein and Daidzein
- Breast Cancer Prevention
- Osteoporosis and Menopause
- Reduction of LDL Cholesterol Levels
Just when you thought it was safe to pronounce (or mispronounce') the word flavonoid, a new class of the amazing phytonutrients has become the rage in the health food stores. They are isoflavones, and they are useful for the prevention and treatment of many diseases.1
If you already know a little about the isoflavones, you probably think of them as simply a source of phytoestrogens, natural estrogen-like substances. You may think of them as being only for women, since women would seem to benefit most. However, although isoflavones are an excellent source of dietary phytoestrogens, they have a number of other activities, ranging from the treatment of rheumatic inflammation, to the prevention of coronary heart disease, to an ability to help control alcoholic symptoms.
The most notable property of isoflavones is their reported ability to reduce the risk of breast cancer. Because of this, soy, which is rich in the isoflavones, Genistein and Daidzein, has become more popular than ever.
Genistein and Daidzein are naturally occurring isoflavones that can also be found in trace amounts in many other foods, mostly grains. They do, however, occur in greatest concentration in clover, alfalfa and soy. These isoflavones have significant anti-cancer effects. Several studies indicate that the isoflavones are potent inhibitors of prostate cancer. Meanwhile, other studies show that they have significant antioxidant activity and may prevent coronary heart disease and arteriosclerosis.
BREAST CANCER PREVENTION
Many lines of evidence suggest that soy isoflavones, and isoflavones from other plants, have cancer-preventive, as well as cancer-curing abilities. One of the most important pieces of evidence is the observation that vegetarians and semi-vegetarians, known to consume higher amounts of soy than non-vegetarians, enjoy a significantly lower risk of many forms of cancer, including cancers of the breast, prostate, uterus and colon.
There are literally hundreds of scientific articles on isoflavones published each year. To review a representative sample of this scientific literature would be a monumental undertaking. Luckily, the researchers Knight and Eden, of the Royal Hospital for Women, in New South Wales, Australia, have published the results of just such an endeavor. They compiled 861 scientific studies and found that, "All studies concurred that phytoestrogens are biologically active in humans. These compounds inhibit the growth of different cancer cell lines in cell culture and animal models. Epidemiological evidence supports the hypothesis that phytoestrogens inhibit cancer formation and growth in humans."
Genistein and Daidzein have both estrogenic and anti-estrogenic activities. This apparent paradox is the key to their cancer-preventive properties. But, in order to understand how isoflavones work, a brief description of estrogen is helpful.
Estrogen is a hormone, and like all hormones, it delivers chemical messages to the cells of the body. Under normal conditions, an estrogen molecule binds to an estrogen receptor on a target cell, and thus signals the cell to divide or perform some other function. Estrogen binding is much like a key fitting a lock. There are a handful of molecules in our environment that have structures similar to that of estrogen. Some are similar enough to fit into the receptor that is intended only for estrogen.
Unfortunately, some pesticides can fit the lock and key mechanism, and initiate cell growth and division. Pesticides may actually cause the kinds of cancer that are linked to high levels of estrogen. The most widely known, of course, is breast cancer.
Breast cancer is the most pervasive and devastating malignancy for women in the United States. Some of the most recent statistics show that a woman's risk of developing breast cancer is one in eight. Logically, those who live in more industrialized areas, where there are high levels of environmental toxic chemical contaminants, are at a much greater risk of developing breast cancer. But, some populations who would be expected to have a high risk of breast cancer rarely contract the disease.
Isoflavones from soy in the diet are apparently protective. Researchers believe this is because soy isoflavones are similar enough to estrogen to bind to estrogen receptors, yet are different enough that they can just barely initiate cell growth and division.
Another way that isoflavones are believed to help prevent breast cancer is by extending the length of women's monthly cycles. In one study at the University of Texas Medical Branch, in Galveston, young women, ages 22-29, were given 12 ounces of soymilk with each of three meals daily for only one month. The result was an increase in the length of the menstrual cycle by an average of 4.4 days. Naturally, the circulating levels of ovarian steroids, which may exacerbate certain forms of cancer, were proportionally reduced. Most researchers agree that there is insufficient research to propose dietary guidelines of isoflavone intake for the prevention of cancer. Still, this study indicates how little is needed to positively affect the body.
Studies also reveal that isoflavones are potent inhibitors of an enzyme called tyrosine kinase, a molecule that helps to signal or initiate tumor cell growth. In addition, isoflavones have been found to inhibit a process called angiogenesis, which is the creation of new blood vessels. When tumors grow, they need blood for nourishment and oxygen, and rely on angiogenesis to get that blood. However, isoflavones prevent angiogenesis and the subsequent tumor growth.
Yet another mechanism by which isoflavones are thought to prevent cancer is through their inherent antioxidant activity. By scavenging free radicals that might attack delicate strands of DNA and initiate cancer, isoflavones contribute even further cancer protection. This is good news for men, who might mistakenly assume that isoflavones are only beneficial to women. It also helps to explain how isoflavones prevent cancers common to men, such as colon, lung, skin and prostate cancer, not to mention leukemia.
Osteoporosis and Menopause
A decline in estrogenic activity, which usually occurs later in a woman's life, can lead to osteoporosis, which occurs when the bones become weak due to insufficient calcium. Another condition brought about by low estrogen activity, menopause, tends to be accompanied by many more symptoms in western countries than in the far east, where isoflavones consumption is high, due to high soy intake.
Research presented at the international conference, "The Role of Soy in Medicine," in Brussels, this past September by Dr. John W. Erdman, of the University of Illinois at Urbana-Champaign concurred with other research that has shown that as little as 40 grams of soy daily leads to significantly higher bone density, the opposite of osteoporosis.
At the same conference, Dr. Paolo Fanti of the University of Kentucky in Lexington characterized the action of soy phytoestrogens as being markedly different from that of endogenous estrogen. Whereas the estrogen produced by the body appears to prevent calcium/mineral loss of existing bone, the phytoestrogens stimulate new bone formation.
This may partially explain the findings of French researcher, Dr. Catala, who reported that soy may reduce the risk of gall stones. Gallstones are composed mostly of cholesterol and calcium, and may be inhibited by a reduction of these two molecules.
Reduction of LDL Cholesterol Levels
The capacity of isoflavones to reduce cholesterol levels touches on one of the most important aspects of their healthful effects. Isoflavones are strongly linked to a reduced risk of atherosclerosis and related coronary artery or coronary heart disease.
Two predominant mechanisms are believed to be at work in the isoflavones' protective role. Soy isoflavones have been shown to specifically reduce low-density lipoprotein (LDL), cholesterol, also known as the bad" cholesterol. Experiments have demonstrated that soy protein devoid isoflavones has little or no effect on cholesterol levels, but soy protein with isoflavones shows significant cholesterol-lowering properties. (Circulation 90 [Suppl 1]:235, 1994 and J Nutr 125 [Suppl 3S]:803S-804S, 1335) Manufacturers of isoflavone-rich soy protein products are generally forthcoming with written verification of their products' isoflavones content.
Isoflavones may also lower the risk of arteriosclerosis and coronary artery disease because they are anti-oxidants. Anti-oxidants are believed to protect against free radicals, which are a byproduct of all oxygen-breathing cells. It is believed that isoflavones can intercept these dangerous molecules before they damage LDL cholesterol molecules in the blood. Damaged LDL are very sticky and will readily form atherosclerotic plaques. Thus, the risk of arteriosclerosis is reduced in two ways: there are fewer LDL molecules due to lower cholesterol levels, and the LDL that are in the blood are less likely to become damaged and sticky since the isoflavones scavenge free radicals.
For some time, the alternative healthcare community has known of the efficacy of the Chinese medicinal herb kudzu in treating alcoholism. However, it is only fairly recently that the active ingredients have been identified. The substances are called Peuriarin, Genistien and Daidzein, and you guessed it, they are isoflavones. Researchers have found evidence that 150 milligrams per kilogram of body weight of kudzu isoflavones can significantly reduce alcohol cravings.
Isoflavones may also decrease inflammation and inflammatory pain. Recent studies of possible causes of rheumatoid inflammation have uncovered that thrombin, which is involved in blood clotting, may also act as a mediator in the rheumatoid inflammatory response. Soy isoflavones inhibit thrombin activity and may contribute to a reduction in inflammation.
To date, research shows that isoflavones have health benefits that include cancer prevention, alcoholism treatment, anti-inflammatory and antioxidant activity, heart disease prevention and providing relief for menopausal symptoms like hot flashes and osteoporosis. The future of these phytonutrients is very promising indeed.