Isoflavones are plant-based compounds primarily found in soybeans that mimic the action of the hormone estrogen. Foods rich in isoflavones possess anti-inflammatory and antioxidant properties, which can help prevent cell damage. Some studies suggest that isoflavone supplements may alleviate menopause symptoms and prevent osteoporosis in postmenopausal people. Additionally, there is some evidence that isoflavone supplements could aid in preventing heart disease and certain cancers. [1]

Foods High in Isoflavones

The richest food sources of isoflavones include: Soybeans, both mature seeds and green (edamame); Some products made from soybeans, including tofu, soymilk, miso, natto, and soy protein powder; Lentils; Split peas; Pinto beans; Lima beans. Isoflavones are also found in small amounts in the following foods: Chickpeas; Fava beans; Pistachios; Peanuts.[2]

Application

Supplements for Menopausal Women

Isoflavones are also known as phytoestrogens. That's because they are plant-based ("phyto" means "from plants") and they have a similar structure to estrogen. This allows isoflavones to bind with estrogen receptors. Depending on the hormone status of a person, isoflavones may affect a person in the same way that estrogen does by producing either estrogenic or antiestrogenic effects. In studies involving isoflavone supplements for menopausal symptoms, some benefits have been shown, such as: Improving fatigue; Improving irritability; Decreasing hot flashes Researchers reviewed 68 publications related to isoflavone consumption and menopausal symptoms and health conditions. They concluded consuming isoflavones reduces hot flashes even accounting for the placebo effect. However, more research is needed using standardized protocols (such as the same type and dosage of isoflavones and study duration) to confirm health effects. Another review of 60 studies found that some plant-based therapies—such as isoflavones—worked to provide a modest reduction in hot flashes and vaginal dryness, but weren't effective for reducing night sweats.[3]

Some case reports indicate that isoflavones in red clover help reduce hot flashes and anxiety during menopause. Although the herb is marketed as a dietary supplement called Promensil, studies on the effects of red clover on menopause symptoms such as hot flashes have had inconsistent results.

Menopause is a biological process that can cause various troublesome symptoms such as hot flashes and emotional changes, but can also increase mortality risk due to subsequent osteoporosis and reduced metabolism. Hormone replacement therapy (HRT) would be the most intuitive way to combat these changes; however, the 2002 Women’s Health Initiative (WHI) study showed that hormone replacement therapy increased the risk of breast cancer, stroke, and coronary heart disease in healthy postmenopausal women. Since then, healthcare professionals and women have been seeking alternative therapies. In Canada for example, it has been found that 60% to 90% of women would consider taking complementary and/or alternative medicine (CAM) for menopausal symptoms, but are concerned about the efficacy and cost. Many patients taking CAM choose not to tell their doctors because they feel doctors are not knowledgeable enough or are biased against CAM. Although some women may prefer lifestyle modification, there is no evidence that lowering the room temperature, exercising, or avoiding triggers such as alcohol and spicy foods can improve hot flashes. Currently, HRT is indicated for the prevention of osteoporosis and relief of the VMS and vulvovaginal atrophy associated with menopause. Moreover, HRT increases bone mineral density (BMD) and reduces the incidence of osteoporotic fractures. Due to the serious side effects mentioned above, HRT should be given in the lowest effective doses for the shortest duration to meet the treatment goals. In fact, the FDA recommends that approved non-estrogen treatments can first be carefully considered before relying solely on HRT for osteoporosis prevention. VMS seriously affects quality of life during menopause and the role of HRT is still fundamental. For affected women who cannot use HRT, evidence has shown that acupuncture, hypnosis, paced respiration, cognitive behavioral therapy, combined preparations of black cohosh, and omega-3 supplements may significantly reduce vasomotor symptoms. Selective Estrogen Receptor Modulators (SERMs), such as Raloxifene (Evista), can be used for both the prevention and treatment of osteoporosis in postmenopausal women. SERMs are non-steroidal compounds with tissue-specific actions, which induce a different response in the ER from estradiol and enhance osteoclast apoptosis. In postmenopausal women, SERMs reduce the risk of vertebral fractures by approximately 30% in patients with a prior vertebral fracture and approximately 55% in patients without a prior vertebral fracture over three years, but do not protect against nonvertebral or hip fractures. Using SERMs do not reduce the risk of coronary heart disease; moreover, they increase hot flashes and also the risk of deep vein thrombosis to a degree similar to that observed with estrogen. Isoflavones, compounds abundant in soybeans, are thought to be responsible for exerting estrogen-like effects, thereby relieving menopausal symptoms. There are two types of estrogen receptors: ERα, the predominant form in the breast and uterus, and ERβ, the predominant form in the cardiovascular system, urogenital tract, and bone. Isoflavones bind weakly to ERα; the affinity of isofolavones to ERβ is higher. The estimated estrogenic effects of different isoflavones using human cell cultures in vitro have shown that the relative potencies are estradiol 100, genistein 0.084, equol 0.061, and daidzein 0.013, respectively. However, isoflavones can circulate at 10,000 times the concentration of estradiol and achieve greater binding potential through abundance. For example, in estrogen-deficient female aromatase knockout mice, isoflavones act as estrogens and improve ovarian morphology.

Although isoflavones will never be as effective as hormone therapy in relieving menopausal symptoms, a survey found that 70% of women would be “satisfied with a nonhormonal intervention that provided at least a 50% reduction in hot flashes”. The safety profile of isoflavones combined with their benefit to overall health makes them a compelling treatment option for postmenopausal women unwilling or unable to take hormone replacement therapy.

Anti-Inflammatory Benefit

Inflammation is a biological response stimulated by pathogens, damaged cells, or irritants. Basically, inflammation is an orchestrated protective process to resolve infection, clear out necrotic cells, and trigger tissue repair. However, this process must be rapid, destructive, specific, and well-controlled in order to avoid the over activation of innate immune response, chronic infectious, and/or inflammatory disorders which may cause serious tissue damage. Solid evidence has shown that the development of various diseases including obesity, diabetes, metabolic syndrome, atherosclerosis, rheumatoid arthritis, and cancer are strongly correlated with inflammation.

Though steroidal or non-steroidal anti-inflammatory drugs are currently used to treat inflammation, these drugs are usually accompanied with unexpected side effects, and also, they are not considered as a good clinical choice for chronic inflammatory disorders. As such, it is urgent to find an effective and safe anti-inflammatory therapy. Numerous epidemiological studies have indicated that vegetarian diets based on fruit and vegetable consumption are beneficial for human health, but the involved food components and the underlying mechanisms still remain unclear. Chinese traditional medicine has had a long history of applying crude plant extracts to treat diseases and disorders exemplified by acute and chronic inflammation. Recent investigations have demonstrated that the polyphenols from plant sources, in particular flavonoids, exhibit anti-inflammatory activity both in vitro and in vivo. This not only provides an explanation for the health benefit of vegetarian diets and Chinese medicine, but also identifies potential agents for treating inflammatory disorders, including possible therapy for life-threatening diseases.

Flavonoids, which include over 6000 identified family members, are a group of phenolic compounds that are widely distributed in plants and fungus. They have been well-known for their antioxidant, antimicrobial, and anti-inflammatory health benefits. Within this family, the focus of research has been on a subclass, isoflavones, which are mainly found in soy beans, soy foods, and legumes. It is well-known that isoflavones act as phytoestrogens to exert pseudohormonal activity by binding to estrogen receptors (ER) in mammals, and also possess antioxidant, anticancer, antimicrobial, and anti-inflammatory activities just like other flavonoids. Daidzein and genistein are the most common isoflavones, whose characteristic chemical structure (B-ring is linked to the C3 position of the C-ring instead of the C2 position) resembles the structure of estrogens, in particular 17-β estradiol. As such, isoflavones elicit either a weak estrogenic (agonistic) or anti-estrogenic (antagonistic) effect, depending on the levels of endogenous estrogens and ER. Isoflavones block the binding of more potent estrogens, potentially playing a role in preventing hormone-related cancer like breast cancer, cervical cancer, and the male prostate or testicular cancer. Interestingly, the incidence of breast and prostate cancers is lower among Asians in comparison to people in the Western world, and this could be related to the significantly different consumption of isoflavones in Asian diets (15–47 mg/day) compared with Western diets (0.15–1.7 mg/day).

References

[1] Chen LR, Ko NY, Chen KH. Isoflavone supplements for menopausal women: a systematic review. Nutrients. 2019;11(11):2649. doi:10.3390/nu11112649

[2] Ahsan M, Khurram Mallick AK. The effect of soy isoflavones on the menopause rating scale scoring in perimenopausal and postmenopausal women: a pilot study. J Clin Diagn Res. 2017 Sep;11(9):FC13–16. doi:10.7860/JCDR/2017/26034.10654

[3] Chen LR, Ko NY, Chen KH. Isoflavone Supplements for Menopausal Women: A Systematic Review. Nutrients. 2019;11(11):2649. Published 2019 Nov 4. doi:10.3390/nu11112649