Does Soy Cause Cancer?

Many vegans and vegetarians depend on soy to be able to maintain a healthy, balanced diet. However, you don’t have to be a vegan or a vegetarian to enjoy soy products. Many people eat soy-based meals on a weekly basis as part of a healthy diet. In recent years, many people have either given up soy or significantly reduced their soy intake. This shift in soy consumption has come from negative reports that portray soy in a negative light claiming it’s harmful.

Many individuals have been left dazed and confused as to how soy really affects them and whether or not it’s harmful. There are many reports out currently stating that soy is a perfect health food. Equally, there are reports stating the opposite, that soy is bad for you and can even cause cancer. To be honest, soy is neither. Soy is complex. Let’s review both sides of such reports and look at the facts.

Does Soy Cause Cancer?

The truth is the few studies available are either inconclusive or do not apply to humans because they are conducted on rodents, which process soy differently than humans do. Additionally, the findings are from poorly designed studies with tests conducted using unrealistic high doses of isoflavones or isolated soy compounds. The amount of soy used in most of these studies is equivalent to one pound of tofu per day. There is currently no evidence in medical literature stating the soy protein isolate is bad for humans.

If soy is part your daily diet, make sure you’re eating a healthy kind of soy. Miso for example, has high levels of sodium. Also, look for organic non-gmo soy. Soy is among the top genetically modified organics. Roughly 90% of soy currently available is genetically modified. Find soy that has the non-gmo project seal on the package to make sure you’re getting the best soy products available.

Soy and Estrogen

Soy contain isoflavones, these are compounds that are chemically similar to estrogen. Two types of these isoflavones can behave like estrogen in the body, though their potency is just a fraction of estrogen found in women.

Isoflavones can also have anti-estrogen properties. They can prevent the natural estrogens from binding to the estrogen receptor. This is important because when estrogen binds to an estrogen receptor it sends out a barrage of signals that can trigger estrogen receptor positive breast tumor growth.

Isoflavones can also stop the formation of estrogen in fat tissue. Additionally, they can stimulate the production of a specific protein that makes estrogen less able to bind to the receptor by binding estrogen in the blood. Isoflavones also have anti-inflammatory and anti-oxidant properties, which can help reduce and even help prevent cancer growth.

Soy and Breast Cancer

Large scale studies of healthy women sharing details about their diet over the course of many years have shown no link between soy and breast cancer. Conversely, they have also shown no signs of breast cancer prevention. Studies in Asian women however, have shown a lower risk of breast cancer when eating a diet high in soy.

It’s also important to consider factors such the amounts of soy consumed. For example women in Asia consume significantly more soy than women in the U.S. Lifelong consumption of soy should also be factored but we lack this type of information.

A recent study of women who have had breast cancer showed that women who consumed 10 mg a day or more of soy had a 25% lower risk of breast cancer recurrence. This study included over 9,000 breast cancer survivors and looked at eating habits as well as other lifestyle factors after cancer. One study was from China and two of them were from the U.S.

Studies in mice without ovaries or a damaged immune system have shown an increased risk of cancer when they ate high amounts of processed soy. In mice with ovaries and a functioning immune system, the studies showed inhibition of tumor growth. However, keep in mind, studies in mice and other animals is irrelevant because rodents process nutrients differently than humans do.

The Scientific Conclusion
Though more studies are needed, the evidence from the studies in women reassures scientists that moderate intake of soy is likely to be safe. Moderate consumption of soy appears to be safe for the general population as well as for breast cancer survivors. In fact, a moderate consumption of soy may help lower your risk for breast cancer and help reduce your cholesterol.

While animal studies have shown mixed results on breast cancer and soy supplements, studies in humans have indicated that soy foods are not harmful to the body. Additionally, soy foods have been linked to lower cholesterol, and lower rates of heart disease because they can replace unhealthy sources of protein such as processed meats and animal fats.

Safe Soy
Remember these two rules to take full advantage of the positive  health benefits of soy. Number one: buy NON-GMO soy. One of the major problems people have with consuming soy and soy-based products is caused by soy that is genetically modified. Only consume soy that has the non-gmo stamp on it. “Organic” does not mean its non-gmo. Soy is one of the top 5 genetically modified crops; this can make it difficult for vegans and vegetarians to maintain a healthy diet especially if you’re new to these diets haven’t yet got all the right information.


Two products we highly recommend are Nature’s Sunshine Tofu Moo and Smart Meal. Tofu Moo is a non-gmo, soy-based protein powder of the highest quality; it can also be used as a milk substitute in cooking. Smart Meal is a meal replacement drink that helps you meet your daily nutritional requirements without the bad fats, bad sugars, or processed substances. Smart Meal comes in three flavors, chai being my personal favorite. For vegans, there is Love and Peas, a delicious vegan protein powder that is also dairy-free, lactose-free, and gluten-free. Love and Peas provides 75% of the daily value of 18 minerals and vitamins needed. All three of these products are of the highest quality, made using non-gmo soy, and are personal favorites of ours that we use daily.

Number two: eat WHOLE soy. Stay away from soy hot dogs, soy hamburger patties, soy chicken tenders and other processed soy products. Stick to whole soy, preferably the fermented kind like tofu, miso, tempeh and edamame. These soy foods have all the positive benefits of soy because they have not been over processed. If you love soy burgers, don’t worry; you can make your own vegetarian patties at home with these easy recipes.

What Are GMO’s?

GMO stands for genetically modified organics. Food should not be modified. However, nearly 95% of most major crops are modified such as: corn, wheat, & soy, just to name a few. Switching to NON-GMO can be overwhelming. To facilitate the transition and to help you learn more, head over to the NON-GMO Project Verified website where you can search by brand name or product categories to find out which products are GMO and which are NON-GMO. They also have information on how GMO’s affect you and your family as well as other very helpful information.  There’s even an app that can help you shop for NON-GMO foods!

Disclaimer: Our services and information do not diagnose or prescribe for disease conditions. Individuals are encouraged to seek competent medical help when those services may be indicated. Individuals accept total responsibility for their own health care and maintenance.

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