The first study to show that the dietary supplement flaxseed may help prevent breast cancer in post- Researchers Investigate Whether Flaxseed Can Help Prevent Breast Cancer (dateline September 4, 2001) | Breast Health News | Imaginis - The Women's Health & Wellness Resource Network

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Researchers Investigate Whether Flaxseed Can Help Prevent Breast Cancer (dateline September 4, 2001)

The first study to show that the dietary supplement flaxseed may help prevent breast cancer in post-menopausal women was recently presented at the national meeting of the American Chemical Society. Flaxseed has long been cultivated from the flax plant to make foods and linens. Previously, only cell and animal studies had linked its use to a lower risk of breast cancer. Though research on flaxseed has only just begun, researchers are encouraged by their initial findings in humans. Because flaxseed appears to lower cancer-related hormone levels, it may provide a protective effect against uterine as prostate cancers as well as breast cancer.

In the study, lead investigator Joanne Slavin, PhD, RD and her colleagues from the University of Minnesota in St. Paul studied 28 post-menopausal nuns living in a convent in central Minnesota. The nuns were selected for the study because they all maintained similar diets at their cafeteria (30% fat, 50% carbohydrates, 20% protein). Over the course of a year, the nuns were given either zero, five, or 10 grams of flaxseed in seven week cycles in addition to their normal diet.

Dr. Slavin and her colleagues found that the nuns who were given flaxseed had lower blood levels of estrogens typically found in post-menopausal women (estrone sulfate and estradiol) compared to the nuns who were not given flaxseed. Because these estrogens have been associated with breast cancer, Dr. Slavin and her team concluded that by lowering the levels of these hormones, flaxseed reduces the risk of breast cancer.

Though the researchers are not certain how flaxseed reduces hormone levels, they believe that its high concentration of lignan may provide clues. Lignans are compounds that can act as either anti-estrogens or weak estrogens, which may help prevent estrogen-dependent cancers including many types of breast cancer, prostate cancer, and uterine cancer. At the American Chemical Society meeting, Dr. Slavin suggested other properties of flaxseed, such as its omega-3 fatty acids and soluble fiber, may also play a role in cancer prevention.

In addition to its possible anti-cancer effects, flaxseed as been promoted by herbalists to help with a variety of conditions including constipation, respiratory problems, sore throat, eczema, menstrual problems, and arthritis. Flaxseed oil has also been said by herbalists to lower cholesterol levels and strengthen the immune system. Currently, flaxseed is being studied to determine whether it can play a role in the prevention of heart disease, high blood pressure, and inflammatory and immune disorders.

Alternative/complementary medicine experts say that flaxseed is most effective when ground into a powder. For example, flaxseed can be ground and then used over cereals, salads, or other foods. In health food stores, flaxseed is available in flour, meal, and seed form. It may also be found in some multi-grain breads, cereals, breakfast bars, and muffins. Flaxseed oil is also available.

Both flaxseed and flaxseed oil need to be refrigerated to prevent them from spoiling. Side effects of taking flaxseed include diarrhea, gas, and nausea. In addition, flaxseed oil should not be used with laxatives or stool softeners. Experts recommend that people with inflammatory disease of the intestine, esophagus, or stomach avoid flaxseed.

Similar to flaxseed, soy has also been associated with a reduced risk of breast cancer. Many soy foods contain phytoestrogens that may offer a protective benefit against estrogen-dependent breast cancer. However, further research is needed to better understand the roles both flaxseed and soy may play in breast cancer prevention. Researchers have cautioned that soy may actually stimulate the growth of breast cancer in women who have a personal history of the disease. Therefore, all women are encouraged to discuss the use of dietary and herbal supplements with their physicians.

Currently, the best way to fight breast cancer is to detect the disease early, when it can more easily be treated. Early breast cancer detection also greatly increases the chances of survival.

Guidelines for early breast cancer detection:

  • All women between 20 and 39 years of age should practice monthly breast self-exams and have physician performed clinical breast exams at least every three years.
  • All women 40 years of age and older should have annual screening mammograms, practice monthly breast self-exams, and have yearly clinical breast exams. The clinical breast exam should be conducted close to and preferably before the scheduled mammogram.
  • Younger women with a family or personal history of breast cancer should talk to their physicians about beginning annual mammograms before age 40.

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