Menopause is the official end of a woman’s menstrual cycle. Women can transition into menopause as early as their mid-30s, but the change typically happens around age 50. A diagnosis is made once 12 months have passed without a menstrual period.
Naturally declining estrogen levels will lead women to experience a number of uncomfortable menopause symptoms, including vaginal dryness, mood swings, reduced sex drive, fatigue, heart palpitations, osteoporosis, and more.
Hormone-replacement therapy (HRT), a popular treatment for easing symptoms, has been found to put great stress on the liver while also increasing the risk of blood clots; stroke; heart disease; urinary incontinence; dementia and memory loss; and cancers such as breast, lung, or colon cancer.
As a result, many women have stopped taking HRT and instead are searching for natural strategies, such as soy and soy isoflavones, to alleviate menopausal symptoms.
This article will detail why soy is good for menopause, covering soy isoflavones benefits for menopause symptoms and how soy benefits postmenopausal health problems.
We will also examine the suggested amount of soy isoflavones to use for menopause, as well as the best dietary sources of soy isoflavones. There are precautions to consider with soy isoflavones that we will detail later in this article. Read on to learn more.
In This Article:
- Is Soy Good for Menopause Symptoms?
- Benefits of Soy Isoflavones for Menopause
- Soy Isoflavones May Benefit Postmenopausal Health Issues
- Amount of Soy Isoflavones to Take for Menopause
- Soy Isoflavones Dietary Sources for Menopause
- Soy Side Effects: Precautions to Consider When Using
- Final Thoughts on Soy and Menopause
Is Soy Good for Menopause Symptoms?
It is interesting that Japanese women suffer fewer hot flashes and night sweats than women in the U.S. In fact, one study found that only seven percent of Japanese women reported hot flashes compared to 55% of American women.
This could be because of the traditional Japanese diet, which contains a lot of vegetable protein rather than animal protein. Japanese women eat a lot of soy-based products, such as tofu, soymilk, soybeans, tempeh, miso, and other soy products.
Soy-based foods and soy supplements have long been praised as a natural therapy for hot flashes and other menopausal symptoms.
Soybeans are high in a type of phytoestrogen called isoflavones. Phytoestrogens are chemicals in plant-based foods that work similarly to estrogens. This means that the human body may be able to use isoflavones as an alternative to human estrogen since isoflavones have estrogen-like structures that bind to estrogen receptors.
When soy isoflavones attach to estrogen receptors unrelated to hormone function, these isoflavones become stimulating, and they act as a blocking agent to receptors that rely on the body’s estrogen.
Soy isoflavones include daidzein, genistein, and other soy metabolites. Commercial soy isoflavones are bound to sugar molecules. But during the digestive process, the sugar is removed, leaving an active aglycone isoflavone.
Intestinal bacteria will then convert most of the aglycone into the daidzein metabolite equol, which is measured in the urine. It is also converted into p-Ethylphenol. Both p-Ethylphenol and equol are absorbed in the blood. Equol is the more important metabolite, which has two forms—the active form S-(-)equol, and R-(+) equol.
However, not all people are capable of breaking down daidzen into equol, and those who are seem to benefit most from soy’s effect on menopause symptoms.
Benefits of Soy Isoflavones for Menopause
What are some of the soy benefits for menopause?
In particular, researchers have spent a lot of time examining how soy isoflavones relieve hot flashes and other menopausal symptoms. At this time, there are more than 60 randomized controlled trials of small sample size that have analyzed the effects of increasing soy isoflavone intake on the severity and frequency of menopausal symptoms.
One study found that women with equol in their urine reported significantly fewer hot flashes, fewer palpitations, less excessive sweating, and less weakness and limb paresthesias when compared to women treated with isoflavone that hadn’t produced equol in their urine.
Remember that Japanese women eat a lot of soy-based foods like tofu, and American women do not. It is not surprising then that only 20% to 30% of Western women produce S-(-)equol, whereas 50% to 60% of Asian women produce S-(-)equol. This may explain why Asian women also have fewer hot flashes and a lower risk of breast cancer.
Studies also show that whole soy products are safe for women who had estrogen-receptor positive breast cancer. Soy isoflavones have also been found to play a role in bone formation.
A study published in the Journal of Hygiene Research in 2010 found that menopausal symptoms and estrogen were improved in women during pre-menopause with a daily dosage of 120 mg of soy isoflavones. In the long-term, this might also reduce the risk of cancer.
A 1990 study of 25 menopausal women published in the British Medical Journal found that vaginal maturation value (MV) increased after two weeks of a soy-rich diet, but not from other phytoestrogen-rich foods like red clover or linseed.
The MV is a method used to measure the estrogenization of the vaginal epithelium, which includes factors like vaginal pH, vaginal moisture, vaginal mucosa, vaginal elasticity, and vaginal fluid volume.
Another study published in Climacteric: The Journal of International Menopause Society in 1998 suggests that phytoestrogens in soy may be used to alleviate some menopausal symptoms. That being said, the rate of hot flashes did not change in this experiment.
However, a 2007 study published in the Journal of Women’s Health discovered that consumption of roasted soybeans three to four times daily would reduce hot flashes and improve menopausal symptoms in general.
For the eight-week study, 60 women with menopause changed their diet to include a half-cup of roasted soybeans divided into three or four portions spaced throughout the day with a total of 25 g of soy protein and 101 mg of aglycone isoflavones.
A review published in the Cochrane Database of Systematic Reviews in 2013 concluded that supplements with mostly genistein would significantly reduce hot flash frequency; however, the same was not true in studies that featured soy isoflavone extracts, dietary soy, or red clover extracts.
At the same time, a systematic review published in the journal Menopause in 2012 found that 30 mg to 80 mg daily of supplemental soy isoflavone extract for six weeks to one year resulted in a 17.4% reduction in hot flash frequency in 13 placebo-controlled trials that featured 1,196 menopausal women.
A meta-analysis of nine trials and 988 women also showed a 30.5% reduction in hot flash severity with 135 mg daily of soy isoflavone extracts for 12 weeks to a year.
It is also important to note that limitations with many of the studies include short durations; small sample sizes; the use of different soy foods that contain varying isoflavones; and the enrollment of women with a wide range of ages and severity of menopausal symptoms.
Some researchers have concluded that since studies have shown conflicting results in a small number of studies, the efficacy of soy-based foods for menopausal symptoms is still unclear.
Soy Isoflavones May Benefit Postmenopausal Health Issues
There are also a number of other potential soy isoflavones benefits for menopause. While some menopausal symptoms can last several years, postmenopausal women have a greater risk of osteoporosis, cardiovascular disease, dementia, and breast and uterine cancers.
Let’s take a look at the research on soy benefits for postmenopausal health conditions and how soy isoflavones may reduce the risk of osteoporosis, cardiovascular disease, dementia, and cancer.
Short-term studies have found that increasing soy intake through soy isoflavones can improve markers of bone formation and resorption or attenuated bone loss in postmenopausal women.
Some researchers believe that the effect of soy isoflavones on bone health may be dependent on whether the person is able to produce the daidzein metabolite equol. But a study published in the American Journal of Clinical Nutrition in 2015 found that soy isoflavone supplementation could increase calcium retention capacity in postmenopausal women regardless of equol-producing capacity.
2. Cardiovascular Disease
Soy isoflavones might also reduce the risk of cardiovascular disease, including stroke, heart attacks, and coronary heart disease.
A study published in the journal Circulation in 2007 found that soy isoflavone intake was associated with a 65% decreased risk of ischemic stroke and 63% lower risk of heart attack in Japanese women between the ages 40 to 59 years old.
A meta-analysis of 64,915 Chinese women between ages 40 and 70 years old published in the Journal of Nutrition in 2003 found a relationship between soy food consumption and a reduced risk of coronary heart disease after a 2.5-year follow-up.
A study published in the journal Menopause in 2015 found that isoflavone intake was associated with better scores in a processing speed test, but worse scores in a verbal memory test in late pre-menopausal and postmenopausal Asian women.
A meta-analysis of 10 randomized controlled trials also published in the journal Menopause in 2015 found a significant improvement in the pooled summary of cognitive function tests in postmenopausal women who supplemented with 60 mg to 160 mg of soy isoflavones daily for six to 30 months.
High consumption of soy isoflavones in Asian countries may contribute to the reduction of breast cancer risk. However, observational studies in Western populations found that the average soy isoflavone intake was low, and therefore not associated with a reduced breast cancer risk.
Research published in the journal Nutrition and Cancer in 2009 shows that lifelong isoflavone exposure may be needed to reduce the risk of developing breast cancer later in life.
A meta-analysis of 9,514 breast cancer survivors followed for 7.4 years, published in the American Journal of Clinical Nutrition in 2014, found that high soy intake was linked with a significant 25% reduction in recurrence of breast tumors in postmenopausal women.
That being said, not all of the research is positive.
For instance, lower circulating estrogen concentrations have been linked to a reduced breast cancer risk in postmenopausal women. However, a meta-analysis published in the journal Advances in Experimental Medicine and Biology in 2009 found no beneficial effect of soy isoflavone supplementation on circulating concentrations of estrogenic hormones, estrone, estradiol, and sex hormone-binding globulin.
As for other cancers, a meta-analysis and systematic review published in the journal Medicine in 2015 also suggests that greater consumption of isoflavone foods is linked with a 19% decreased risk of uterine cancer in postmenopausal women.
Research published in the Journal of National Cancer Institute in 2012 also found that isoflavones were linked with a 34% lower risk of uterine cancer.
Amount of Soy Isoflavones to Take for Menopause
What’s the correct dosage of soy isoflavones to take for menopausal symptoms and postmenopausal health issues?
The following are the recommended amounts of soy isoflavones consumed daily for menopausal symptoms and related health issues, according to the North American Menopause Society.
- 40 mg to 80 mg daily to lower hot flashes
- 50 mg daily for bone health
- 40 mg to 80 mg daily to strengthen blood vessels and improve blood pressure
- 50 mg daily for cholesterol reduction
Soy Isoflavones Dietary Sources for Menopause
There are many foods that contain soy, or whole soybeans—also called edamame. Soybeans and tofu are found in many Chinese and Japanese dishes, while tofu is popular in creamy dishes, salad dressings, shakes, pastas, stir fries, and scrambles.
Sprouted certified organic and genetically modified-free tofu are considered better options than highly processed soy products and soy supplements with soy protein isolates and concentrates.
It is also best to avoid “soy junk foods” like soy ice cream, soy burgers, soy oil, soy sauce, soy cheese, soymilk, soy yogurt, roasted soybeans, and roasted soybean butters.
Instead, fermented soy products like natto, miso, and tempeh are available, which have various health benefits associated with menopause. For instance, natto may help balance hormones, while tempeh could potentially increase bone density and decrease cholesterol.
The following is table that lists soy foods and their total isoflavones and other isoflavones, daidzein, genistein, and glycitein. This is only a guide as isoflavone content of soy foods can vary with the different brands.
|Food||Serving||Total Isoflavones (mg)||Daidzein (mg)||Genistein (mg)||Glycitein (mg)|
|Soy protein concentrate, alcohol washed||3.5 oz||11.5||5.8||5.3||1.5|
|Soy protein concentrate, aqueous washed||3.5 oz||94.6||38.2||52.8||4.9|
|Tempeh, cooked||3 oz||30.3||11.1||18||1.2|
|Soybeans, mature seeds, boiled||1/2 cup||56||26.5||26.9||3.2|
|Low-fat soymilk||1 cup||6.2||2.4||3.7||0.1|
|Dry roasted soybeans||1 oz||41.6||17.4||21.2||3.7|
|Tofu yogurt||1.2 cup||21.3||7.5||12.3||1.6|
|Soft tofu||3 oz||19.2||8.1||10.1||1.4|
|Soy burger, unprepared||1 patty||4.5||1.6||3.5||0.4|
|Green soybeans (edamame), boiled||1/2 cup||16.1||6.7||6.3||4.1|
|Soy sausage||3 links||10.8||3.3||6.9||1.7|
|Cheddar soy cheese||1 oz||1.9||0.5||0.6||0.8|
Soy Side Effects: Precautions to Consider When Using
Although there are some benefits of soy and soy isoflavones, there are also some precautions to consider before consuming them.
For starters, soy is one of the most common genetically modified foods in the world, and that is why certified GMO-free and organic soy products are best. The phytoestrogens in soy products like tofu can have an estrogen-like effect on the body that blocks normal estrogen production, and this is linked to breast cancer.
Soy also contains goitrogenic compounds like the soy isoflavone genistein, which is considered a thyroid hormone blocker that can interfere with thyroid hormone production and cause hypothyroidism.
Soy products are also high in anti-nutrients like phytates, which can block mineral absorption and cause deficiencies in zinc, iron, and calcium. Other soy anti-nutrients include saponins, lectins, oligosaccharides, oxalates, and protease inhibitors.
Soy has also been negatively linked to dementia and Alzheimer’s disease. Research shows that people who ate tofu in mid-life had reduced cognitive function during later stages of their lives.
A study published in the journal Dementia and Geriatric Cognitive Disorders in 2008 found that eating high amounts of tofu was linked with worse memory, while consumption of higher amounts of tempeh was shown to improve memory.
The B12 analogs in soy resemble vitamin B12, which is why soy foods like tofu can lead to vitamin B12 deficiency, especially in vegans and vegetarians. Soy products also contain strong enzyme inhibitors, which can block the activity of pancreatic enzyme trypsin and other proteolytic enzymes needed for protein digestion.
Although some studies support soy for heart health, research published in the Journal of Clinical Investigation in 2006 suggests that a soy-rich diet has negative effects on heart health.
The study found that mice fed a soy-based diet exhibited significantly worse hypertrophic cardiomyopathy (HCM) than mice given a soy-free diet. HCM is a condition where the heart muscle becomes thick, making it more difficult for the heart to pump blood.
Soy is also one of the top allergic foods. The phytoestrogens in soy may also interfere with breast cancer drugs tamoxifen (“Nolvadex”) and raloxifene (“Evista”), which are used to prevent and treat osteoporosis in postmenopausal women.
Furthermore, soy may interact with estrogen medications and other hormonal drugs. The food should also be avoided in people taking antidepressants like MAOIs (monoamine oxidase inhibitors) tranylcypromine (“Parnate”) and phenelzine (“Nardil”).
Soy may also increase bleeding, especially if you are on blood thinners like clopidogrel (“Plavix”) or warfarin (“Coumadin”).
Final Thoughts on Soy and Menopause
Hormone-replacement therapy (HRT) has been the standard treatment for managing menopause symptoms in women for decades. Research indicating that it puts stress on the liver and increases the risk for heart disease; stroke; blood clots; dementia and memory loss; incontinence; abdominal vaginal bleeding; and cancers like uterine, breast, lung, and colon cancer, has turned many to nature-based remedies like soy isoflavones.
Supplementation with isoflavones is 40% less effective than HRT in relieving menopausal hot flashes and requires more time to reach its therapeutic effect. The menopause-related benefits of soy isoflavones also appear to be based on a person’s ability to metabolize daidzein into equol.
However, research shows that soy isoflavones can relieve menopausal symptoms and positively affect postmenopausal health issues like osteoporosis, cardiovascular disease, dementia, and breast and uterine cancer.
Rather than consume unfermented soy products, it is better to choose certified GMO-free and organic soy products and fermented soy products like natto, miso, and tempeh.
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