Tofu, soymilk, miso, tempeh, edamame—these and other soy products, including the soybeans themselves, are high in nutrients you tend to associate with other legumes, including fiber, iron, magnesium, potassium, protein, and zinc.
Soybeans naturally contain a class of phytoestrogens called isoflavones. People hear the word “estrogen” in the word “phytoestrogens” and assume that means soy has estrogen-like effects. Not necessarily. Estrogen has positive effects in some tissues and potentially negative effects in others. For example, high levels of estrogen can be good for the bones but can increase the likelihood of developing breast cancer. Ideally, you’d like what’s called a “selective estrogen receptor modulator” in your body that would have proestrogenic effects in some tissues and antiestrogenic effects in others. Well, that’s what soy phytoestrogens appear to be. Soy seems to lower breast cancer risk, an antiestrogenic effect, but can also help reduce menopausal hot-flash symptoms, a proestrogenic effect. So, by eating soy, you may be able to enjoy the best of both worlds.
What about soy for women with breast cancer? Overall, researchers have found that women diagnosed with breast cancer who ate the most soy lived significantly longer and had a significantly lower risk of breast cancer recurrence than those who ate less. The quantity of phytoestrogens found in just a single cup of soymilk may reduce the risk of breast cancer returning by 25 percent. The improvement in survival for those eating more soy foods was found both in women whose tumors were responsive to estrogen (estrogen-receptor positive breast cancer) and those whose tumors were not (estrogen-receptor negative breast cancer). This also held true for both young women and older women. In one study, for example, 90 percent of the breast cancer patients who ate the most soy phytoestrogens after diagnosis were still alive five years later, while half of those who ate little to no soy were dead.
Soy consumption has also been shown to benefit our kidneys, which appear to handle plant protein very differently from animal protein. Within hours of eating meat, our kidneys rev up into hyperfiltration mode. But, an equivalent amount of plant protein causes virtually no noticeable stress on the kidneys. Eat some tuna, and within three hours, your kidney filtration rate can shoot up 36 percent. But eating the same amount of protein in the form of tofu doesn’t appear to place any additional strain on the kidneys.
Image Credit: margouillatphotos / Thinkstock. This image has been modified.
Popular Videos for Soy
All Videos for Soy
The Best Advice on Diet and Cancer
What the best available balance of evidence says right now about what to eat and avoid to reduce your risk of cancer.
Coconut Water and Depression
The science behind the marketing of foods for antidepressant effects.
Benefits of Beans for Peripheral Vascular Disease
Do legumes (beans, chickpeas, split peas, and lentils) just work to prevent disease or can they help treat and reverse it as well?
Should Women with Fibroids Avoid Soy?
Is soy harmful, harmless, or helpful when it comes to uterine fibroids?
Shark Cartilage Supplements Put to the Test to Cure Cancer
Yes, shark cartilage supplements carry risks, but so do many cancer treatments. The question is does it work?
Dr. Greger’s Daily Dozen Checklist
In my book How Not to Die I center my recommendations around a Daily Dozen checklist of all the things I try to fit into my daily routine.
Does Chocolate Cause Acne?
What are the effects of dairy products, sugar, and chocolate on pimple formation?
How to Convert Into an Equol Producer
Certain gut bacteria can supercharge the benefits of soy foods, resulting in even more bone protection, better control of menopausal symptoms, and lower prostate cancer risk. The question is how can we foster the growth of these good bacteria?
Soy Phytoestrogens for Menopause Hot Flashes
Does soy food consumption explain why Japanese women appear so protected from hot flash symptoms?
Dr. Greger’s Daily Dozen Checklist
In my book How Not to Die, I center my recommendations around a Daily Dozen checklist of all the things I try to fit into my daily routine.
Arsenic in Rice Milk, Rice Krispies, & Brown Rice Syrup
I recommend people switch away from using rice milk.
The Role of Soy Foods in Prostate Cancer Prevention & Treatment
Soy is put to the test for the treatment of prostate cancer.