Benefits of Soy Isoflavones - Dr. Sarah Brewer (2023)

are isoflavonesPolyphenolsAntioxidants that act like plant hormones. They are similar in structure to human estrogen and are popular dietary supplements for treating symptoms associated with menopause and premenstrual syndrome. Isoflavone supplements may also protect against this.heart disease,osteoporosisand cancers ofProstateand in men and breast in women.

dietary isoflavones

About a thousand different plant isoflavones have been identified, but only five with estrogenic activity are found in our diet in significant amounts:

  • Genistein, daidzein and glycitein are mainly derived from itMilitarye araruta japonesa (kudzu)
  • Formononetin and biochanin A (which are metabolized to daidzein and genistein) are derived fromChickpea, lentils and mung beans.

In Japan, where soy is a staple food, intake of isoflavones is 50 mg to 100 mg per day for men and women, compared to a typical Western intake of just 2 mg to 5 mg of isoflavones per day. Blood levels of isoflavones in Japan are therefore up to 110 times higher than those normally found in the West.

Importance of probiotic bacteria

Isoflavones from dietary plants are mostly consumed in an inactive form, bound to sugars to form glycosides such as genistin and daidzin. Once ingested, intestinal bacteria ferment these sugar isoflavones to release the active forms (aglycones like genistein and daidzein).

The metabolism of isoflavones varies widely from person to person, and their absorption is greater in those with slower intestinal transit times (i.e., tendency tocold).

Some people also haveprobioticGut bacteria (such as Lactobacillus, Bacteroides, and Bifidobacterium species) that can metabolize daidzein into a more potent estrogen called equol. In fact, humans can be divided into two distinct groups: equol producers and nonquol producers.

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Equol has greater antioxidant activity than any other isoflavone and equol producers reap greater health benefitsisoflavoneas unequal producers. This could explain why some studies show a benefit from isoflavone supplements while others do not.

This also means it's a good idea if you're taking isoflavone supplements.probioticDietary supplements to boost your levels or take a prebioticoligosaccharidesSupplement to feed those you already have.

Isoflavones versus human estrogens

Compared to estradiol, the strongest human estrogen, the plant worksphytoestrogensas genistein is about 100 times weaker. Despite this, isoflavones have a normalizing effect on estrogen status. Isoflavones can stimulate estrogen receptors to provide a beneficial boost in estrogen when levels are low during menopause. On the other hand, isoflavones can block the effects of excess human estrogen by occupying and blocking receptors so that they interact less with more potent human estrogens. Isoflavones also stimulate the production of sex hormone-binding globulin (SHBG), which reduces levels of free active estrogen in the circulation.

Isoflavones and premenstrual syndrome

One study of 23 women with premenstrual syndrome found that taking soy protein provided 68 mg per dayI am isoflavonessignificantly less headache, breast tenderness, cramping and swelling compared to placebo.

In Japan, a study of 144 women found that women classified as producing equol were 2.3 times less likely to experience symptoms of equol.premenstrual syndromeas equol producers.

Isoflavones and menopause

Soy isoflavones are commonly used to reduce menopausal hot flashes and night sweats.

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This is shown by the results of 16 studies with 1710 womenI am isoflavonescan reduce hot flashes by 25.2% more than a placebo, making it about 45% as effective as full prescribed estradiol. However, soy isoflavones acted more slowly, taking at least 13 weeks to reach half their maximum effect, compared to 3 weeks for estradiol. If you take soy isoflavone supplements, they will provide incremental benefits over a year or more, with 80% of their maximum effect being reached at 48 weeks, so don't give up too soon.

Soy and heart disease

Soy isoflavones may reduce the risk of coronary artery disease in several ways. In addition to having antioxidant and anti-inflammatory effects, isoflavones also interact with estrogen receptors in the circulatory system to dilate coronary arteries, reduce arterial stiffness, lower blood pressure, and reduce blood viscosity to prevent unwanted blood clots.

good recording ofMilitaryFood can significantly lower total and “bad” LDL cholesterol and triglycerides, while significantly raising “good” HDL cholesterol. Those with high cholesterol levels benefited the most. Results from 17 studies involving more than 17,200 incidents of cardiovascular disease found that those with the highest soy intake were about 17% less likely to have a heart attack or stroke than those with the lowest intake.

While much research involves postmenopausal women, a study of 61 Scottish men (aged 45-59) found that this is on the rise.isoflavonesTaking it for just 5 weeks resulted in significant reductions in blood pressure and LDL cholesterol - even compared to an olive oil placebo. Significant increases in high-density lipoprotein cholesterol were also observed. The researchers concluded that increasing levels of soy protein (at least 20 g) and isoflavones (at least 80 mg) in the diet would reduce the risk of heart disease even in high-risk middle-aged men.

However, some studies have not found an association between isoflavone intake and cardiovascular disease, which may be due to the balance state of the participants.

isoflavones and osteoporosis

Isoflavones mimic the effects of natural estrogen on bone and should theoretically increase the activity of bone-forming cells and also decrease the activity of cells that dissolve bone. This is the case, with studies showing that soyisoflavonesignificantly increased bone mineral density by 54% and markers of bone resorption by 23% in women taking doses greater than 75 mg per day.

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Therefore, taking soy isoflavones may help protect against postmenopausal osteoporosis.

Isoflavones and memory

Eating a soy-rich diet improves memory and thought processes in healthy young college students (both men and women) and in postmenopausal women. In a study of 33 postmenopausal women not on hormone replacement therapy, they tookisoflavonefor 12 weeks showed significantly greater improvements in memory recall, sustained attention tasks, reverse learning rules and task planning than those who received placebo.

Isoflavones and protection against prostate cancer

I am isoflavonesmay offer men some protection against prostate cancer. Urologists have found that even in at-risk men, taking soy isoflavones reduces the likelihood of a prostate cancer diagnosis by 51% and has a good safety profile.

Isoflavones and breast cancer protection

This is indicated by the results of 35 studiesI am isoflavoneshave a protective effect against breast cancer for both premenopausal and postmenopausal women, but the effect is stronger in Asian women, which may be related to their equi status. In Asian countries, women with the highest intake of soy isoflavones were 41% less likely to develop breast cancer than women with the lowest intake, both pre- and post-menopausal. In postmenopausal women in Western countries, intake of soy isoflavones was associated with an 8% lower risk of breast cancer.

There is growing recognition that women with a history of breast cancer can benefit from soy isoflavones.

A study that followed nearly 2,000 women who survived breast cancer for 6 years said: "I am isoflavonesconsumption in amounts comparable to those in Asian populations may reduce the risk of breast cancer recurrence in women receiving tamoxifen therapy and that dietary supplements do not appear to impair the effectiveness of tamoxifen.

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This was recently confirmed in a study involving 6235 women with breast cancer who were followed for 9 years. Those with the highest intake ofdietary isoflavones(1.5 mg or more per day) were 21% less likely to die of medical causes during follow-up than those with the lowest isoflavone intake (less than 0.3 mg per day).

OAmerican Institute for Cancer Research (AICR)also found soy to be safe for breast cancer patients and survivors.


Red clover isoflavones are not found naturally in food, but contain isoflavones similar to soy and are used in dietary supplements to treat menopausal symptoms. Results from five studies suggest that women taking supplements containing 80 mg of red clover isoflavones per day experienced an average of 3.6 fewerHot flashes during menopauseper day than those on placebo.

Dose Isoflavona

A typical dose of soy isoflavones is 40 mg to 100 mg of isoflavones per day. Doses of at least 75 mg are recommended for best effects.

For products containing soy protein, 60g of soy protein provides 45mg of isoflavones.

Safety of Isoflavones

If you have a history of breast (or prostate) cancer, always follow your doctor's advice on whether or not to take isoflavone supplements.

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photo credit:buyonego/flickr;


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