Soy for menopausal symptoms

Soy is high in isoflavones. Isoflavones are a type of phytoestrogen. Phytoestrogens are estrogen-like chemicals found in plants. In some ways, the human body can use them like estrogens.¹

• Traditional Asian diets are high in soy, ranging from 40mg to 80mg of isoflavones each day.
• The average American eats very little soy-less than 3mg of isoflavones each day.

A diet high in isoflavones may be why women in Japan, Korea, and China have low rates of menopausal symptoms, estrogen-related cancers (such as breast cancer), and heart disease.² By contrast, Americans and Asian immigrants who eat few or no isoflavones have higher rates of these conditions.¹ (However, there may yet be another explanation for these health differences.)

Are soy isoflavones effective?

Osteoporosis. Eating lots of soy may help keep your bones strong, especially in the first 10 years after menopause.³ (This is when your estrogen level drops and rapid bone loss happens.)

Menopause symptoms. Soy products may improve menopausal symptoms, such as hot flashes. This is based on mixed evidence. So far, studies have used many different soy sources and different measures of success, which are difficult for experts to compare. Soy isoflavone (rather than soy protein) studies have shown the most promise for hot flash treatment.⁴

Are soy isoflavones safe?

Eating and drinking soy on a daily basis has no known risks. For some people, it upsets the digestive system.

The long-term effects of diet high in soy have not been well-studied.⁴ High soy intake can't be considered safe until more research is done.^{1, 5}

Some experts think that soy phytoestrogen does not lead to cancer like estrogen can. But this is not proven. Experts do not yet know if a high-soy diet is a risk for women who have had breast cancer.⁴

Making soy a part of your daily diet

Isoflavones are short-acting. If you use soy for health reasons, try to eat it throughout the day, rather than all at once. Try to eat 40mg to 80mg of isoflavones each day.^{6, 5}

Remember that soy protein is different than soy isoflavone. A high-protein soy food may or may not have a large amount of isoflavones in it.

Soy comes in many forms, so you have a lot of choices for adding soy isoflavones to your diet.

Citations

1. Mishra SI, et al (2003). Phytoestrogens and breast cancer prevention: What is the evidence? American Journal of Obstetrics and Gynecology, 188(5): S66–S70.

2. Kronenberg F, Fugh-Berman A (2002). Complementary and alternative medicine for menopausal symptoms: A review of randomized, controlled trials. Annals of Internal Medicine, 137(10): 805–813.

3. Zhang X, et al. (2005). Prospective cohort study of soy food consumption and risk of bone fracture among postmenopausal women. Archives of Internal Medicine, 165(16): 1890–1895.

4. Balk E, et al. (2005). Effects of Soy on Health Outcomes. Evidence Report/Technology Assessment No. 126 (AHRQ Publication No. 05–E024–1). Rockville, MD: Agency for Healthcare Research and Quality. Also available online: http://www.ahrq.gov/clinic/epcsums/soysum.pdf.

5. American College of Obstetricians and Gynecologists (2001). Use of botanicals for management of menopausal symptoms. ACOG Practice Bulletin No. 28. Obstetrics and Gynecology, 97(6, Suppl): 1–11.

6. Tice JA, et al. (2003). Phytoestrogen supplements for the treatment of hot flashes: The isoflavone clover extract (ICE) study, a randomized controlled trial. JAMA, 290(2): 207–214.

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