Skip to main content
ASK AN EXPERT
Got a question about a health story in the news or a health topic? Here's your chance to get an answer. Send us your questions about general health topics, diet and fitness and mental health. If your question is chosen, it could be featured on CNN.com's health page with an answer from one of our health experts, or by a participant in the CNNhealth community.




* CNN encourages you to contribute a question. By submitting a question, you agree to the following terms found below.
You may not post any unlawful, threatening, libelous, defamatory, obscene, pornographic or other material that would violate the law. By submitting your question, you hereby give CNN the right, but not the obligation, to post, air, edit, exhibit, telecast, cablecast, webcast, re-use, publish, reproduce, use, license, print, distribute or otherwise use your questions(s) and accompanying personal identifying and other information you provide via all forms of media now known or hereafter devised, worldwide, in perpetuity. CNN Privacy Statment.
Thank you for your question!

It will be reviewed and considered for posting on CNNHealth.com. Questions and comments are moderated by CNN and will not appear until after they have been reviewed and approved. Unfortunately, because of the voume of questions we receive, not all can be posted.

Submit another question or Go back to CNNHealth.com

Read answers from our experts: Living Well | Diet & Fitness | Mental Health | Conditions

Expert Q&A

How much is too much phytoestrogen?

Asked by Keyana, Spokane, Washington

Open quote
Close quote

I have two questions. What is considered to be a high/harmful amount of phytoestrogen in a woman's diet per day? And should a woman who has had cancer not take estrogen replacements or eat a diet high in phytoestrogens?

Expert Bio Picture

Diet and Fitness Expert Dr. Melina Jampolis Physician Nutrition Specialist

Expert answer

Hi, Keyana. These are interesting questions. I'm going to assume that you are talking about breast cancer since the association of phytoestrogen consumption and breast cancer risk is the most concerning to many women.

Phytoestrogens are plant-based compounds that act like the hormone estrogen. There are two basic types of phytoestrogens: isoflavones and lignans.

Soy products are the most common source of isoflavones, and the controversy surrounding cancer and phytoestrogens are related to soy products. To provide you with the best possible response to your question, I turned to noted cancer nutrition expert Rachel Beller, who addresses this question on a regular basis at the Beller Nutritional Institute in Los Angeles.

Beller explained that while phytoestrogens are similar to human estrogens, their effect on human estrogen levels has not been well-researched because plant estrogens are 1,000 times weaker than the estrogen produced in our bodies.

Many studies suggest that soy isoflavones' estrogen-like effects are probably too weak to have any significant consequence on breast tissue in healthy women -- that includes breast cancer survivors.

Regarding the association with breast cancer, Beller points to a 2011 study published in Cancer Epidemiology, Biomarkers & Prevention that found soy to be safe and favorable, even for breast cancer survivors, when eaten in its natural, unprocessed state -- for example, tofu, tempeh, edamame, miso soup.

In fact, experts agree that fermented soy (miso, tempeh) is good for you. The fermentation process alters the chemical makeup of soy, which reduces the level of isoflavones by as much as 300%.

Therefore fermented soy foods have three times less of the chemical in question.

While this study does not conclusively establish the safety of soy, phytoestrogens aside, soy is not only an excellent source of heart healthy plant-based protein, which is encouraged in the latest dietary guidelines for Americans, it also contains dozens of nutrients that also appear to help fight cancer development.

These nutrients can protect cells from becoming damaged, encourage faulty cells to die instead of reproducing, regulate cell growth and even improve cell communication. These are all things that help strengthen your body against cancer and heart disease.

A study has also shown that consumption of soy early in life may help protect against breast cancer later in life, even if it may be more questionable for post-menopausal women.

What's also noteworthy is that Asians have been eating soy foods in large amounts for centuries, and their traditional soy-rich diets are associated with lower risks of breast and prostate cancer than Western diets.

Beller goes on to say that the "bad rap" that soy's been getting is due to the fact that when we hear something's "good for you," we process it to the max, extract the good stuff and concentrate it, which basically makes it lose its original identity.

Skip the processed soy foods and supplements, especially if you have a history of breast cancer.

The bottom line: If you have no history of breast cancer, there is no known high or harmful amount of phytoestrogens, and foods such as unprocessed soy are an important part of a healthy diet.

If you have a history of breast cancer, as with nutrition in general, you should not focus on a single food or nutrient. The key is moderation.

The phytoestrogens consumed by eating moderate amounts of relatively whole and unrefined forms of soy foods (two to three times a week) can be considered part of a healthy, complete diet.

Regarding estrogen replacement therapy, according to the National Cancer Institute, "Studies of hormone use to treat menopausal symptoms in breast cancer survivors have produced conflicting results," so I suggest speaking with your physician to determine the best approach for you.

Follow Dr. Jampolis on Twitter

More Q&A

  • CNN's Medical UnitCNN's medical unit brings you the best experts available to answer your questions about current events and health issues that matter most to you.
Will jogging hurt an obese person's joints?asked by: Asked by John Simmet; St. Paul, Minnesota
Is creatine a safe supplement?asked by: Asked by Ralph; New York
What foods cause flatulence?asked by: Asked by Peter; United States

CNN Comment Policy: CNN encourages you to add a comment to this discussion. You may not post any unlawful, threatening, defamatory, obscene, pornographic or other material that would violate the law. All comments should be relevant to the topic and remain respectful of other authors and commenters. You are solely responsible for your own comments, the consequences of posting those comments, and the consequences of any reliance by you on the comments of others. By submitting your comment, you hereby give CNN the right, but not the obligation, to post, air, edit, exhibit, telecast, cablecast, webcast, re-use, publish, reproduce, use, license, print, distribute or otherwise use your comment(s) and accompanying personal identifying and other information you provide via all forms of media now known or hereafter devised, worldwide, in perpetuity. CNN Privacy Statement.

The information contained on this page does not and is not intended to convey medical advice. CNN is not responsible for any actions or inaction on your part based on the information that is presented here. Please consult a physician or medical professional for personal medical advice or treatment.