Many plants produce chemicals called phytohormones, which mimic or interact with hormones in humans and animals. Phytoestrogens are plant-produced chemicals that mimic estrogen, the primary sex hormone in women. Estrogen is manufactured mainly in the ovaries and is responsible for the menstrual cycle. Men's bodies produce estrogen to a lesser degree. Estrogen is crucial to the female reproductive cycle; supplementation can be used to treat hot flashes and other menopausal symptoms, such as night sweats, that women experience.
What and Where
The two main categories of phytoestrogen are isoflavones and lignans. You are exposed to phytoestrogens primarily through your diet. According to the Centers for Disease Control and Prevention, or CDC, phytoestrogens are excreted from the body within 24 hours, mainly through urine. Fruits, such as dates, cherries and apples, and vegetables, such as carrots and potatoes, contain varying amounts of phytoestrogens. A 4-oz. serving of peanuts contains less than 0.1 mg of phytoestrogens; other foods, such as soy, contain much higher amounts. A 3-oz. serving of tofu contains 23 mg of phytoestrogens.
Concern
It remains unclear whether overexposure to phytoestrogens results in adverse bodily reactions. High levels of estrogen have been linked to promoting breast cancer. The possibility that phytoestrogens may mimic estrogen brings safety into question. Research is aimed at uncovering whether and to what extent phytoestrogens exert estrogenic effects in the body.
Clinical Data
According to an article published in "American Journal of Clinical Nutrition," emerging clinical data suggests that a diet rich in phytoestrogens, namely those from soy and flaxseed, exhibits beneficial effects in regard to obesity and diabetes. In obese individuals, dietary soy intake increased high-density lipoprotein, or HDL cholesterol, and decreased low-density lipoprotein, or LDL cholesterol. According to the article, the component responsible for these beneficial effects has yet to be determined.
Potential Menopausal Treatment Benefit
Doctors prescribe estrogen to treat menopausal symptoms in women, but according to the CDC, this raises concern over cancer risks. Because phytoestrogens are weaker, researchers have looked at phytoestrogen supplementation as a potential alternative treatment for menopausal symptoms, with the idea that this could lower the cancer risk associated with estrogen medication. Results are conflicting. While some studies suggest that phytoestrogen supplements could improve menopausal symptoms, such as hot flashes, a 2004 study, published in "Obstetrics and Gynecology," concluded that increasing dietary intake of phytoestrogens, such as those found in soy, exerted no clinically significant improvement.
References
- Center for Disease Control and Prevention: Phytoestrogens
- "American Journal of Clinical Nutrition"; Beneficial Role of Dietary Phytoestrogens in Obesity and Diabetes; Sam J. Bhathena et al.; May 2002
- "Obstetrics and Gynecology"; Phytoestrogens for Treatment of Menopausal Symptoms: A Systematic Review; E.E. Krebs et al.; October 2004
