Soy Foods, Pumpkin Seeds and Sunflower Seeds Reduce Breast Cancer Risk
July 29, 2012 by Robert Wascher
Filed under A Cancer Prevention Guide for the Human Race, Breast Cancer, Cancer, Cancer Prevention, Flaxseed, Healthy Diet, Menopause, Nutrition, Phytoestrogens, Pumpkin Seeds, Raloxifine, Soy, Soy Foods, Sunflower Seeds, Weekly Health Update, breast cancer prevention, breast cancer risk, cancer risk, diet, estrogen, lifestyle, polyphenols, sex hormones, tamoxifen, whole grains
A new study links the consumption of soy foods, pumpkins seeds, and sunflower seeds with a decreased risk of breast cancer.
SOY FOODS, PUMPKIN SEEDS AND SUNFLOWER SEEDS REDUCE BREAST CANCER RISK
As I discuss in my bestselling book, A Cancer Prevention Guide for the Human Race, phytoestrogens are substances found in plant-based foods that have weak estrogen-like effects in the body. As estrogen is a known risk factor for breast cancer, there has been understandable concern that phytoestrogens, if consumed regularly, may lead to an increased risk of breast cancer over time. While the data supporting this hypothesis has been both weak and contradictory thus far, some of the strongest available data regarding phytoestrogen intake and breast cancer risk has, counterintuitively, linked certain phytoestrogen-rich foods, and especially soy foods like tofu, with a decreased lifetime risk of breast cancer, particularly when consumed before and during the onset of puberty, as I discuss in my book.
Now, a newly published German study further suggests that the regular consumption of at least some phytoestrogen-rich foods may significantly decrease breast cancer risk, particularly later in life, after menopause. In this public health study, 2,884 postmenopausal women diagnosed with breast cancer and 5,509 age-matched “controls” without breast cancer underwent detailed assessments of their dietary habits. In addition to using a scientifically validated food-frequency questionnaire, additional specific questions regarding the consumption of phytoestrogen-rich foods were asked of all of the 8,393 women who participated in this case-control clinical study. Importantly, the volunteers’ individual risk factors for breast cancer were assessed and accounted for when the study’s researchers analyzed their data. This public health study appears in the current issue of the journal Nutrition and Cancer.
Among all foods known to contain phytoestrogens, three foods were found to be significantly associated with a lower risk of breast cancer among postmenopausal women. Specifically, the regular consumption of soy foods was linked to a 17 percent reduction in breast cancer risk, while the routine intake of sunflower and pumpkin seeds was associated with a 34 percent reduction in breast cancer risk. At the same time, the consumption of flaxseed, which contains very high levels of phytoestrogens, did not appear to be linked with a decrease in breast cancer risk in this study.
The results of this study add further evidence that at least some forms of phytoestrogens may actually decrease the risk of breast cancer, even though they are able to weakly stimulate the same hormonal receptors that estrogen normally stimulates. While this finding may at first seem contradictory, recent research has shown that these plant-derived nutritional substances actually have rather complex effects on estrogen receptors within breast cells and other hormone-sensitive cells. In fact, in many cases, phytoestrogens may actually block the effects of estrogen on estrogen receptors within breast cells, thus acting more like medications that are regularly used to reduce the risk of breast cancer recurrence in patients with estrogen-sensitive tumors, including tamoxifen and raloxifene.
I will end my review of this new public health study by reminding readers that studies such as this one rely upon relatively weak research methods, and the findings of these types of public health studies are less compelling, in general, than “gold standard” prospective, randomized, blinded, placebo-controlled clinical research studies. Unfortunately, the overwhelming majority of cancer prevention research data published to date has been derived from relatively less powerful public health studies like this particular study. However, given the enormous expense and resources necessary to perform large prospective, randomized, blinded, placebo-controlled clinical studies, and the extended period of time that is required to arrive at meaningful observations within such studies, we are left primarily with questionnaire-based public health studies such as this one in an effort to better understand potential links between diet and cancer risk. For a much more detailed evidence-based discussion of the impact of diet and other lifestyle factors on cancer risk, purchase your copy of A Cancer Prevention Guide for the Human Race from your favorite bookstore (available in both print and e-book formats).
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For a groundbreaking overview of cancer risks, and evidence-based strategies to reduce your risk of developing cancer, order your copy of my bestselling book, “A Cancer Prevention Guide for the Human Race,” from Amazon, Barnes & Noble, Books-A-Million, Vroman’s Bookstore, and other fine bookstores!
Within one week of publication, A Cancer Prevention Guide for the Human Race was ranked #6 among all cancer-related books on the Amazon.com “Top 100 Bestseller’s List” for Kindle e-books. Within three months of publication, A Cancer Prevention Guide for the Human Race was the #1 book on the Amazon.com “Top 100 New Book Releases in Cancer” list.
Disclaimer: As always, my advice to readers is to seek the advice of your physician before making any significant changes in medications, diet, or level of physical activity
Dr. Wascher is an oncologic surgeon, professor of surgery, cancer researcher, oncology consultant, and a widely published author
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