In recent years, soy has been called a “miracle” food, a food good for lowering your risk of heart disease, treating postmenopausal symptoms, such as hot flashes, and preventing breast cancer, but that’s only part of the story.  Soy may not be as miraculous as the FDA wants you to believe, and it may even have adverse effects on your health, especially if you’re a woman.

In October of 2002, I was forced to switch from drinking ricemilk to soymilk when we moved to a community where ricemilk was not available. About a month later, I found a lump in my right breast. As a 26 year old, I knew that the probability of it being malignant (cancerous) was small, especially since only 20% of all breast lumps are found to be malignant tumors. Even so, the fear that it could be breast cancer was still there. A few days after my doctor’s visit, an ultrasound revealed that it was a benign (non-cancerous) cyst. Thankful for this good news, I still had many questions about what caused this cyst, especially since I don’t consume chocolate or caffeine, both known to play a role in cyst development and hormone imbalances. In the past, I had done a little reading about soy and knew that certain chemicals in soy products might cause a hormone imbalance, so on a hunch, I asked my doctor if she thought that this cyst could be related to my switch from ricemilk to soymilk. When she said yes and explained that soy is well-known (in the medical community) for promoting the growth of estrogenic (estrogen-related) tumors and cysts, I decided right then and there to do some serious research on the subject and what I found was both scary and enlightening.

Soy contains chemicals called isoflavones, or phyto-estrogens, which are a weak form of the female hormone estrogen. For postmenopausal women who no longer produce estrogen, estrogen replacement therapy is effective in reducing many symptoms associated with menopause, such as hot flashes. Since the amount of estrogen needed to give symptom relief is small, many women are choosing to try soy products that contain isoflavones, as opposed to synthetically produced estrogen, for symptomatic relief. However, pre menopausal women produce huge amounts of estrogen and, although the estrogen in soy products is infinitesimal in comparison, it still may be enough to cause a hormone imbalance, especially if taken in the form of a dietary supplement as opposed to simply consuming soy from food sources. These hormone imbalances can become severe enough to disrupt the normal menstrual cycle and trigger the growth of estrogenic tumors, both benign and malignant and cysts.

“The problem, researchers say, is that isoflavones are phytoestrogens, a weak form of estrogen that could have a drug-like effect in the body. This may be pronounced in postmenopausal women. Some studies suggest that high isoflavone levels might increase the risk of cancer, particularly breast cancer. Research data, however, are far from conclusive, and some studies show just the opposite--that under some conditions, soy may help prevent breast cancer. It is this scientific conundrum, where evidence simultaneously points to benefits and possible risks, that is causing some researchers to urge caution” (Henkel).

The reason that the FDA claims that soy is safe is because soy is a very complicated food containing a variety of different chemicals, any of which may have positive and negative effects on health. For example, “Animal study results, some of which date back to 1959, link soy isoflavones to possible thyroid disorders, such as goiter. A 1997 study in Biochemical Pharmacology identified (the isoflavones) genistein and daidzein as inhibitors of thyroid peroxidase, which data suggest may prompt goiter and autoimmune disorders of the thyroid” (FDA Consumer).

On the other hand, in 1999 the FDA spent a year reviewing available human studies that examined the effects of soy protein on cholesterol. What they discovered is that soy protein has been shown to reduce levels of low density lipoproteins (LDL), bad cholesterol, while not having an effect on the level of high density lipoproteins (HDL), good cholesterol. Since heart disease is the number one killer here in the states, “Killing nearly 960,000 Americans each year and accounting for more than 40% of all deaths,” (www.cdc.gov) the FDA was excited to discover that soy could potentially save hundreds of thousands of lives each year. This is why they are now actively trying to get you to consume soy on a daily basis and it’s also why they decided to let manufacturers add the phrase, “A daily diet containing 25 grams of soy protein, also low in saturated fat and cholesterol, may reduce the risk of heart disease.”

The “FDA has purposely limited its health claim to foods containing intact soy protein. The claim does not extend to isolated substances from soy protein such as the isoflavones genistein and daidzein” (FDA Consumer). The problem is that any soy product that you buy at the grocery store such as soymilk, tofu, miso, tempeh, textured soy protein, soy flour will also contain isoflavones. What’s even scarier is that many of these products, whether food or dietary supplements, actually proudly advertise that they contain “The important soy isoflavones – genistein and daidzein.” 

Today, there’s just not adequate research on the safety of soy products, especially isoflavone supplements. Between the isoflavones and other unidentified compounds that make up any soy product on the market, the FDA acknowledges that more research is necessary to determine its safety and to provide the consumer with the ability to make a well-educated decision about whether or not to include soy as part of their daily diet. As long as it reduces heart disease and the research remains limited, the FDA will continue to recommend 25 grams of soy protein as a part of a balanced daily diet. Unfortunately, you can’t just eat soy protein alone because any soy product on the market will contain isoflavones, so it’s best to arm yourself with knowledge so that you know the potential risks involved with consuming soy products.

“Daniel Sheehan, Ph.D., director of the Estrogen Knowledge Base Program at FDA's National Center for Toxicological Research, also urges caution in consumption of soy isoflavones. In formal comments submitted to the public record of his own agency while FDA was reviewing the health claim, Sheehan, along with colleague Daniel Doerge, Ph.D., wrote, "While isoflavones may have beneficial effects at some ages or circumstances, this cannot be assumed to be true at all ages. Isoflavones are like other estrogens in that they are two-edged swords, conferring both benefits and risks.”” (FDA Consumer).

So, before you decide to include soy as a part of your daily diet, be sure to speak with your physician, primarily your gynecologist, so that you can carefully evaluate whether soy is right for you. Based on the limited research that’s available right now, it’s advisable to avoid soy isoflavone supplementation because the risk of developing cancer and thyroid disease are simply too great.

Whatever your decision, learn to become vigilant about performing a monthly breast self-exam and if you discover a lump, contact your physician immediately because it could very well save your life.

Resources:

Henkel, John. Soy: Health Claims for Soy Protein, Questions About Other Components. U.S. Food and Drug Administration. http://www.cfsan.fda.gov/~dms/fdsoypr.html. Access Date: March 7, 2003.

Cornforth, Tracee. Women’s Health: Combined HRT and Increased Breast Cancer Risk. www.askjeeves.com; Question asked: What causes a cyst? Access Date: March 7, 2003.

The Centers for Disease Control and Prevention. U.S. Department of Health and Human Services. Programs in Brief: Cardiovascular Health: Tackling Our Nation’s Leading Killer, http://www.cdc.gov/programs/chronic1.htm, Feb. 2002. Access Date: March 10, 2003.