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Is Soy Bad For Breast Cancer

Does The Form Of Soy Exposure Matter

Soy and Breast Cancer: Good or Bad?

A variety of soy products are available in the marketplace, but the three main categories are traditional Asian soy foods, such as tofu and miso products based on concentrated soy protein powders, especially soy protein isolate and isoflavone supplements and foods to which isoflavones have been added. Often, cautionary warnings regarding soy consumption by breast cancer patients are restricted to supplements or supplements and powders . Although it is unclear whether any form of soy or isoflavone pills poses a risk to breast cancer patients, the available data do not appear to warrant differentiating among the various forms of isoflavone-containing products.

In work by Helferich and colleagues described previously, soy protein isolate with various concentrations of genistein stimulated mammary tumor growth in mice implanted with MCF-7 cells to a similar extent as did isolated genistein. In the work by Hargreaves et al. in which pS2 levels were increased in breast cells taken from premenopausal women and in the work by Petrakis et al. in which NAF secretion increased, subjects were fed textured vegetable protein in the former study and isolated soy protein in the latter study. Furthermore, soy foods , concentrated soy protein powders and isolated isoflavones have all appeared to exert estrogen-like effects on other tissues in human subjects. Lastly, the pharmacokinetics of pure isoflavones are similar to those of isoflavones administered via food .

Is Soy Safe To Eat After Breast Cancer

New Study Suggests Soy Will Not Increase Risk of Return of Breast Cancer

April 5, 2011 â For years, breast cancer survivors were often counseled to avoid soy foods and supplements because of estrogen-like effects that might theoretically cause breast tumors to grow.

Now, a new study of more than 18,312 women shows that eating soy foods did not increase risk of breast cancer recurrence.

The new findings are being presented at the American Association for Cancer Research 102nd Annual Meeting in Orlando, Fla.

âIf you regularly eat soy, you donât need to worry or avoid it, and women who want to lead a healthy life, can safely include some soy in their diets,â says study researcher Xiao Oh Shu, MD, PhD, a professor of medicine at Vanderbilt Epidemiology Center of Vanderbilt University Medical Center in Nashville, Tenn.

In addition to the isoflavones which may act like estrogens in the body, âsoy has many anticancer properties, antioxidants, nutrients, micronutrients, or vitamins that may contribute to its beneficial effect on health,â Shu says.

Shu and colleagues analyzed data from four large studies of women with a history of breast cancer diagnosed between ages 20 and 83. Soy intake was assessed using questionnaires in all of these studies. The study only looked at soy foods, not supplements.

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Estrogenic And Nonestrogenic Isoflavone Properties

Isoflavones have a spatial conformation similar to that of mammalian estrogens, bind to estrogen receptors and affect estrogen-regulated gene products . Isoflavones have traditionally been considered to be weak estrogens, possessing between 105 and 102 of the activity of 17-estradiol on a molar basis . It is really not possible, however, to arrive at a general estimate of activity because estrogenicity varies greatly depending on the assay used. Furthermore, isoflavones may bind less tightly than estrogen to serum proteins making them more available to tissues and they may be tissue selective, exerting quite pronounced estrogen-like effects in some tissues such as the coronary vessels but not in other tissues such as the endometrium . However, even the lower estimates of estrogenicity suggest that isoflavones have the potential to exert physiologic effects in humans consuming soy foods because serum isoflavone levels will be 100-1000 times higher than endogenous estrogen levels . The consumption of modest amounts of isolated isoflavones was shown to exert potentially important biological effects in humans, such as enhancing systemic arterial compliance and reducing urinary levels of 5-hydroxymethyl-2-deoxyuridine, a marker for oxidative DNA damage .

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Lets Set The Record Straight: Phytoestrogen And Estrogen Are Not The Same

So, where does the idea come from that soy can increase your risk for breast cancer? Much of the confusion surrounding soy comes from a component of the legume called isoflavones. Isoflavones are compounds found in plants. The compounds have a similar chemical structure to human estrogen. For this reason, isoflavones are also known as phytoestrogens.

Many people confuse human estrogen with phytoestrogen, but they are not the same thing. Phytoestrogens behave differently than estrogen in the body and may help prevent cancer, heart disease and inflammation.

Soy phytoestrogens are much weaker than human estrogen. While more research is needed, human population studies show regular inclusion of soy is not harmful and may actually be helpful in preventing breast cancer, says Groeger.

Soy Intake While On Aromatase Inhibitors Or Tamoxifen

Does Soy Really Decrease the Risk of Breast Cancer?

While soy may help relieve your hot flashes, researchers caution postmenopausal women against having too high a dose of soy, particularly in the form of supplements that contain high amounts of soy isoflavones. And if youâve had estrogen-sensitive breast cancer, and are taking a selective estrogen receptor modulator, such as tamoxifen, or an aromatase inhibitors, such as exemestane, itâs a good idea to refrain from soy. The soy isoflavone genistein may counteract estrogen suppressorsand that would make your post-treatment medication less effective.

After youâve completed a full course of estrogen suppressors you can start including soy in your diet again, in modest amounts. But first, talk with your oncologist. If you still want the benefits of isoflavones, try dining on legumes, whole grains, and nuts. On the other hand, a good reason to avoid soy altogether is if you know that youâre allergic to it. You should also skip soy if you have a thyroid disorder or goiter.

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Obesity Smoking Lifestyle And Genetics Are Riskier Than Soy

Unfortunately when people worry about something like soy intake when it may not be a risk for breast cancer they may not be worrying as much as they should about true risk factors.

Removing attention from these can be the greater risk, Dr. Roesch says.

These other behavioral risk factors for breast cancer like obesity, smoking at an early age, a sedentary lifestyle or high saturated fat intake are bigger concerns than consuming plant estrogens like soy, she says.

Genetics also play a major role in a persons risk of developing certain types of breast cancer.

Is Soy Bad For You Or Is It Full Of Benefits

By Rachael Link, MS, RD

Without a doubt, soy is one of the most controversial products on the planet. In fact, ask a handful of health experts is soy bad for you? and youre likely to get a dozen different responses.

While some claim that it can disrupt hormone levels, tank thyroid health and contribute to cancer, others point out that it can improve heart health, boost fertility and keep cholesterol levels in check.

So is soy bad for you? And how much soy is too much? Keep reading for everything you need to know about the health effects of this incredibly common yet controversial ingredient.

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What Every Breast Cancer Patient Should Eat

This is an important read for patients and supporters alike!

Over 2.8 million women in the U.S. have a history of breast cancer, including those getting treated now. Aside from skin cancer, breast cancer is the most common cancer diagnosis. especially for women . And the foods we eat could play an integral role in potentially fighting cancer and keeping the body as healthy as possible during treatment.

Why Eat Healthy?

A nutritious diet will fuel the immune system by providing important vitamins, minerals, and antioxidants that nourish healthy cells, say nutritionists Jane Schwartz, RD, and Stephanie Goodman, CNC. A nourishing diet also provides lots of fiber, which feeds the beneficial bacteria that are critical for immune health.

Cancer-fighting foods, like leafy greens, berries, and mushrooms, can also help you manage your weight. That keeps your body healthy in many ways, including reducing excess body around the waist, which can trigger cancer cell growth due to increased insulin production.

Registered Dietitian MS, RD, CP., who is also the author of Plant-Based Nutrition, advocates healthy foods for breast cancer patients, and emphasizes eating lots of fruits, vegetables, and a couple servings of whole soy products daily, which can reduce the risk of breast cancer incidence and recurrence.

Whether you snack on carrots and oranges or eat salads and drink tea, healthy dietary choices could have a big impact on your bodys ability to prevent and fight cancer.

Higher Concentrations Of Isoflavones In Mouse Studies

Soy Foods: Good or bad in breast cancer?

Because of the differences in how soy isoflavones are metabolized in mice and humans, the mice in these were exposed to much higher concentrations of isoflavones than the amounts human beings typically eat. Researchers have concluded that the higher concentrations mean the outcomes are likely to be different for the two species.

When researchers conducted similar soy , whose biology is much closer to human biology, they found no increased risk of breast cancer among the primates who consumed soy.

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How Much And What Type Of Soy Should You Eat

It is best to eat soy in moderation as part of healthful meals that include plenty of vegetables, fruits, and whole grains. You can find natural sources of soy in foods like edamame, soy milk, and tofu. The U.S. Food and Drug Administration says that eating 25 grams of soy per day offers health benefits, such as reducing the risk of heart disease.

People who are making lifestyle changes after a cancer diagnosis often start eating more fruits and vegetables and consume less red meat and processed foods. The question of whether it is OK to eat soy comes up often, especially for patients with hormone receptor-positive breast cancer. The good news is it appears that patients do not need to avoid soy in their diets, although it is best to limit intake to moderate amounts. Norah Lynn Henry, MD, PhD, FASCO, an Associate Professor in the University of Michigan’s Division of Hematology/Oncology in the Department of Internal Medicine, Breast Oncology Disease Lead at the Rogel Cancer Center, and Cancer.Net Associate Editor in Breast Cancer

You may have also heard of soy protein powder, which can be added to shakes or used while baking to boost the amount of protein. Read the nutrition label on soy protein powders to find the total grams of soy in each serving to ensure you stay within the recommended 25 grams. You should also look at the label to choose products with lower sodium, fewer added sugars, and fewer additional ingredients.

Dangers Of Soy And Breast Cancer

The American Cancer Society suggests that estrogen plays a role in breast cancer. Similar to how estrogen-replacement/hormonal therapy can increase the risk of breast cancer in post-menopausal women, women who have had more exposure to estrogen over their lives are at increased risk of developing breast cancer. This leads us to question the safety of consuming estrogen-like compounds in soy.

One of the drugs that is used to treat breast cancer works by binding to estrogen receptors, much like how isoflavones bind to selective estrogen receptor modulators . Here comes the potential role of isoflavones. If you recall, isoflavones compete with endogenous estrogen for the estrogen receptors, are more likely to bind to some of the receptors but have weaker effects, and act somewhat like the drugs used in treatment.

Another review had similar findings suggesting that a diet high in soy compared with diets with a low soy did not change the risk of initial breast cancer but does decrease the risk of death by 15% and recurrence by 25%. Another group of researchers found that moderate soy protein was the most beneficial for people who already have been diagnosed with breast cancer.

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Why Are Some People Concerned About Soy

Soybeans and foods derived from them have been part of the human diet for centuries. Nevertheless, some people worry about including soy in their diet due to the following areas of concern:

  • Estrogen-mimicking effects. Soy isoflavones are often thought to mimic the female reproductive hormone estrogen. Although theyre similar in structure to this hormone, soy isoflavones have weaker and slightly different effects than estrogen (
  • 65 ).

Keep in mind that while these concerns are common, few of them are supported by sound science. Moreover, when negative effects have been observed, they often followed the consumption of very large amounts of soy.

For instance, men who reported experiencing feminizing effects from soy consumed amounts up to 9 times larger than the average intake of men with soy-rich diets. Although possible, it would be difficult for most people to eat that much soy each day .


The concerns above are commonly cited when it comes to soy. Generally, few are supported by strong science, and more research is needed to confirm the remaining.

Scientists Untangle The Soy

Is Soy Bad for You? The Research on Menopause, Breast ...

1 February 17

To eat soy or not: That’s the question many U.S. women have been asking. Tofu, miso paste and other soybean-based foods are high-quality sources of protein that are low in calories and saturated fat. And studies have shown that they can help prevent cancer.

Yet many doctors recommend that women who have, or are at risk of developing, a common form of breast cancer called estrogen-receptor-positive breast cancer avoid eating soybean-based foods because they contain compounds called isoflavones. Some studies suggest that isoflavones can mimic the hormone estrogen and encourage tumor growth.

Now, in an animal study, researchers at the Georgetown Lombardi Comprehensive Cancer Center in Washington, D.C., have uncovered a possible reason for the apparent Jekyll-and-Hyde nature of soy how it can both prevent cancer and fuel its spread.

The researchers found that rats that were given soybean isoflavones to eat throughout their lives in particular, one type of soybean isoflavone called genistein had improved immunity against cancer. But rats that weren’t given the isoflavone until after developing breast cancer didn’t have that same immune response to kill cancer cells. Instead, these rats had higher rates of cancer growth and higher rates of recurrence after their tumors were removed.

In other words, the paradox is in the timing. It may be that soy consumption is protective only if started before cancer develops.

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Soy Foods Are More Than Just Tofu And Soy Sauce

Soy foods are made from soybeansa crop that, until the 1980s, has been used in America primarily as livestock feed, but has been a part of the Asian diet for many generations. Soy is available as edamame , tofu, soy milk, soy powder and flour, miso paste, tempeh, oil, and textured vegetable protein . Soy shows up in many meat analog productsmeatless meatballs, “burger” style crumbles, and even bacon-like strips and chicken-shaped nuggets.

Myth: Soy Only Affects Breast Cancers That Are Sensitive To Estrogen

While itâs true that soy isoflavones play a bigger role in estrogen-receptor positive breast cancers, early research links it to a lower risk of other types of breast cancer.

That finding comes from a study of 756 Chinese women who had breast cancer and about 1,000 others who didnât have the disease. All of the women answered questions about their diets, including how much soy they ate. Those who said they ate more soy were less likely to have any type of breast cancer, compared to those who ate the least.

That finding doesnât prove that soy prevented breast cancer in any of the women. Other things could be involved.

âMore research still needs to be done,â Meyers says. âIt could be that people who eat more soy have healthier lifestyles in general.â

Stay tuned to see if that proves to be helpful across the board, whether you eat tofu regularly, pour soy milk on your breakfast cereal, or snack on edamame.

Show Sources

Denise Millstine, MD, director of integrative medicine, Mayo Clinic consultant, womenâs health, Mayo Clinic Breast Clinic.

UCSF Medical Center: âA Guide to Foods Rich in Soy.â

Hilakivi-Clarke, L. Journal of Nutrition, December 2010.

Lee, S. American Journal of Clinical Nutrition, June 2009.

Wu, A. British Journal of Cancer, January 2008.

United States Department of Agriculture: âUSDA Database for the Isoflavone Content of Selected Foods.â

Shike, M. Journal of the National Cancer Institute, September 2014.

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Does Soy Pose A Breast Cancer Risk

There has been a lot of news attention about it and you have probably heard a family member or friend talking about it the connection between soy and cancer. More specifically, many people were worried for a time that there is a connection between soy consumption and breast cancer. There are many foods that contain soy, such as tofu, edamame, soy sauce, tofu, soy flour, soybean oil, miso, soy milk, tamari, teriyaki sauce, tempeh and more. Soy is a plant fiber full of important vitamins and amino acids. With soy being in so many foods, many women became very concerned they were increasing their risk of cancer. The American Cancer Society explains the concern behind soy consumption to provide a more clear background for the discussion, Soy foods contain isoflavones, which are chemically similar to estrogens. Two major types, genistein and daidzein, can act like estrogen in the body, although at a very small fraction of the potency of circulating free estrogen in women. These effects can be good or bad. Let me explain. It is well established that estrogen is linked to hormonally-sensitive cancers in women, such as breast and endometrial cancer. Breast cells contain estrogen receptors, and when the key joins with the lock , a series of signals are sent which can spur on estrogen-receptor positive breast tumor growth.

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