The Good Life: Dietary Hormones and Cancer
Noel Peterson, ND
Belinda had gone off Premarin after her breast cancer diagnosis. The lumpectomy had been a success, but the menopausal hot flashes were severe since she was off estrogen and kept her sweating day and night. "I know I can't take hormones, but these hot flashes and vaginal dryness are driving me crazy. I've got to get some relief."
Her diet was excellent. I asked if she had ever tried tofu. "How about tempeh or soy milk? No? Until now, you've not had a good reason to make any of these foods staples in your diet. But consider this: A diet high in soy products will eliminate most of your menopausal symptoms, lower your cholesterol, and lower your risk of developing breast cancer again." How? Through the magic of phytoestrogens.
Phytoestrogens are plant-derived substances that have estrogen-like activity. They are generally considered to be weak estrogens and therefore do not have the same potency of the hormones produced in your body. Soybeans are the most significant dietary source of the phytoestrogens.
It has been observed that Japanese women who consume a traditional Japanese diet high in soybeans have several hundred times the phytoestrogen blood levels of women consuming Western diets. Japanese women on a traditional high soy diet have 30 to 75 percent lower blood levels of Estrone and Estradiol, two estrogens most associated with an increased risk of cancer.
Western women have a three-fold higher blood level of Estradiol than women on an Asian diet, while at the same time, the Asian women excrete more than twice the amount of beneficial estrogens in their urine compared to women on the Western diet. In other words, women on the Western diet hold onto their estrogen, whereas the high soy Asian diet helps women eliminate and detoxify estrogen out of their systems at a much higher rate, thereby lowering their risk of cancer.
One class of phytoestrogens are known as the isoflavones, and include Genistein and Daidzein. Both are found in high concentration in soybean products, with the highest levels found in tempeh and tofu. Just 40 grams (approx-imately 4 tablespoons) of soy protein isolate, or one cup of tempeh, can raise your isoflavone levels by 1,000 fold!
Isoflavones function as modulators of estrogen balance in the body via their ability to bind to estrogen receptor sites on breast and prostate tissue. In this way they have prohormonal and antihormonal effects. Through their prohormonal effects, they can stimulate hormone receptors and control the symptoms of menopause and osteoporosis. They are also capable of inhibiting estrogen activity through a process called competitive inhibition, i.e., binding to an estrogen receptor site so that a cancer causing compound is unable to do so. This may explain some of the reduction of breast and prostate cancers with soy products. By preventing binding of hormones to receptors that trigger cancer, soy products can prevent cancer. In other words, if the soybean isoflavone is bound to the receptor, the receptor cannot receive the cancer stimulating message from the toxic hormone.
Belinda did change to a soy based diet and the results were fantastic. She still had hot flashes, but they were much milder and less frequent. The other symptoms improved, too. And best of all, she knew she was preventing a recurrence of her cancer with every bite!