Women going through menopause sometimes boost their intake of soy, a plant food rich in substances called isoflavones. Isoflavones are known to mimic the action of estrogen, a female hormone known to decrease during menopause. By offering estrogen-like effects, soy is said to help with certain health problems linked to loss of estrogen (such as hot flashes, declines in bone mass, and increases in cholesterol levels). Here's a look at some key study findings on soy and menopause.
1) Hot Flashes
Research on soy and hot flashes has yielded mixed results, according to a 2006 report from The Journal of the American Medical Association. Reviewing 43 clinical trials on nonhormonal therapies for hot flashes, researchers found conflicting evidence for the use of soy isoflavones.
In a more recent report (published in a 2008 issue of Menopause), scientists found that women given soy isoflavone supplements at a daily dose of 40 mg had a 52 percent drop in hot flashes (compared with a 39 percent reduction in women given a placebo). The authors of the study (which lasted 12 weeks and involved 147 menopausal women) concluded that soy isoflavone supplementation may be an "effective and acceptable alternative to hormone treatment for menopausal hot flashes." (In other research, long-term use of hormone therapy has been found to increase risk of heart disease and stroke.)
2) Bone Health
Soy may offer some protection against menopause-related bone loss, according to a 2010 research review published in the journal Bone. Analyzing 28 studies with a total of 2,477 participants, the review's authors found that treatment with soy isoflavone supplements was linked to a moderate decrease in levels of deoxypyridinoline (a substance excreted during bone breakdown). However, the review also found that soy isoflavone supplementation may not promote the formation of new bone.
During menopause, levels of LDL ("bad") cholesterol may increase while levels of HDL ("good") may decrease. In a 2006 report from the journal Climacteric, researchers concluded that soy isoflavones might have a "small but positive health effect" on blood fat concentrations (as well as on cognitive function).
Using Soy During Menopause
Although soy may be of some value to women undergoing menopause, it's important to take caution before increasing your soy consumption or using soy supplements. For instance, some research suggests that taking in large amounts of soy may speed up cancer growth in people with estrogen-sensitive breast tumors. If you're considering upping your intake of soy during menopause, talk to your doctor to find out what amount of soy is safe for you.
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Khaodhiar L, Ricciotti HA, Li L, Pan W, Schickel M, Zhou J, Blackburn GL. "Daidzein-rich isoflavone aglycones are potentially effective in reducing hot flashes in menopausal women." Menopause. 2008 Jan-Feb;15(1):125-32.
National Institutes of Health. "Soy: MedlinePlus Medical Encyclopedia". November 2010.
Nelson HD, Vesco KK, Haney E, Fu R, Nedrow A, Miller J, Nicolaidis C, Walker M, Humphrey L. "Nonhormonal therapies for menopausal hot flashes: systematic review and meta-analysis." JAMA. 2006 May 3;295(17):2057-71.
Taku K, Melby MK, Kurzer MS, Mizuno S, Watanabe S, Ishimi Y. "Effects of soy isoflavone supplements on bone turnover markers in menopausal women: systematic review and meta-analysis of randomized controlled trials." Bone. 2010 Aug;47(2):413-23.