What are Estrogens (and why do we need them)?
Estrogens are a group of hormones that play an essential role in growth and development. In young girls and teens, they are responsible for breast development and puberty. During fertile years, estrogens stimulate the development of follicles for ovulation and promote growth of the uterine lining to prepare for pregnancy. Estrogens are also important for bone growth, hair growth, cardiovascular health, memory, sleep, and mood. Declining levels of estrogen contribute to the many uncomfortable symptoms that can be associated with menopause.
Despite these essential roles, having too much estrogen can cause several health concerns. An excess of estrogen can lead to symptoms including PMS, irregular or uncomfortable periods, or problems with sleep, mood, and anxiety. If prolonged, high estrogen levels can lead to cardiovascular disease as well as breast and ovarian cancers.
What’s the Link to Breast Cancer?
Breast cells contain many estrogen receptors; when estrogen binds to them, these cells will grow. In normal breast cells, the binding of estrogen promotes normal growth and development, as in puberty or pregnancy. In cancers, the binding of estrogen fuels uncontrolled growth leading to the formation of tumours. These tumours are said to be estrogen-receptor (ER) positive. Approximately 2 out of every 3 breast cancers are this type. Thus, estrogens fuel the growth of the majority of breast cancers.
However, not all estrogens are the same. Some of the estrogens made by our bodies are more likely to cause tumour growth while others are protective. A diet rich in broccoli, cauliflower, cabbage, Brussels sprouts and kale will promote healthier, more protective forms of estrogen.
Many estrogen-like compounds can be taken in from the world around us. Chemicals in plastics, pesticides, and many cosmetic products have structures that are very similar to estrogens. Once in the body, they can bind to estrogen receptors. They tend to bind more tightly than the estrogens we make ourselves, and have stronger stimulatory effects. Minimizing the use of plastics, choosing organic foods, and using natural cosmetics can help to reduce exposure to these types of estrogen. A healthy liver and digestive system along with a diet rich in fibre, will help the body naturally rid itself of these harmful estrogens.
Estrogen-like compounds are also found in plants. These compounds, called phytoestrogens, can also bind to estrogen receptors. However, they tend to bind loosely, triggering only a mild estrogen-like effect. They can also exert a protective effect because once they bind they block the receptors, preventing the binding of the stronger chemical estrogens. Flax seeds, sesame seeds and legumes (especially soybeans) are rich with phytoestrogens. A plant based diet including a variety of fruits, vegetables, nuts, seeds and beans tends to be full of phytoestrogens.
In summary, too little estrogen can lead to weak bones, infertility, and many uncomfortable hormone-related symptoms. But too much estrogen can contribute to the growth of breast cancer. The key is keeping estrogens in a healthy balance. A healthy digestive system, a diet rich in phytoestrogens and fibre, and a lifestyle that includes minimizing chemical exposure will all contribute to this balance, and is likely to be reduce risk of breast cancer or its recurrence.
References
American Cancer Society. Hormone therapy for breast cancer. https://www.cancer.org/cancer/breast-cancer/treatment/hormone-therapy-for-breast-cancer.html, 2017.
Zhang FF, Haslam DE, Terry MB, et al. Dietary isoflavone intake and all-cause mortality in breast cancer survivors: the Breast Cancer Family Registry. Cancer. Published online March 6, 2017.
Smith-Warner SA, Spiegelman D, Yaun SS, et al. Intake of fruits and vegetables and risk of breast cancer: a pooled analysis of cohort studies. JAMA 2001;285(6):769-776.
Thongprakaisang S, Thiantanawat A, Rangkadilok N, Suriyo T, Satayavivad J. Glyphosate induces human breast cancer cells growth via estrogen receptors. Food Chem Toxicol. 2013. Sep;59:129-36. Epub 2013 Jun 10.
Phytoestrogens, Breast Cancer Prevention Partners. https://www.bcpp.org/resource/phytoestrogens/
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