New Research Confirms Health Benefits of Soy Consumption for Women - American Society for Nutrition (2025)

Advances in Nutrition review finds soy consumption does not interfere with estrogenicity, but rather it can support women’s health and a healthier planet

The results of human studies indicate that soy lowers your risk for heart disease, resulting in health benefits claims for soy in Canada and the US. These potential heart health benefits are particularly important for women as cardiovascular disease is the leading cause of death among women. In particular, cardiovascular disease risk increases significantly during menopause. Moreover, studies have shown that cardiovascular disease among women is under-recognized and under-treated.

There is also substantial evidence that soy isoflavones, a compound found in soy, reduces the risk of estrogen-sensitive cancers such as breast, ovarian, and endometrial cancer. Moreover, soy isoflavones can improve bone health and memory.

Finally, soy isoflavones can help alleviate menopausal symptoms such as hot flashes. While many women use hormone replacement therapy to manage the symptoms of menopause, not all women are good candidates for this therapy due to contraindications, including cardiovascular disease and estrogen-sensitive cancers. In these cases, soy isoflavones may be an appropriate treatment option, according to a 2023 position statement of The North American Menopause Society.

Despite the health benefits that soy foods can offer women, controversies around the effects of soy foods and their components, especially soy isoflavones, are a barrier to their acceptance. Soy isoflavones are a type of plant estrogen, also known as a phytoestrogen, that are similar in chemical structure to human estrogen. These isoflavones can bind to human estrogen receptors in the body and therefore potentially interfere with estrogenicity, a term which refers to the way the human body produces and deploys estrogen to regulate various bodily functions.

The negative beliefs surrounding soy isoflavones, including the belief that they may worsen outcomes for estrogen-sensitive breast cancer, have been predominantly driven by the results of animal studies. These studies, however, have limited implications for human health, in part due to differences in how rodents and humans metabolize soy isoflavones. Moreover, human studies on the effects of soy isoflavones have not replicated the negative health risks reported in comparable animal studies. Nonetheless, consumption of soy foods is low among North Americans, with only 3-4% reporting consumption of a soy-containing product on any given day.

There has been a recent shift in both national dietary guidelines and cardiovascular clinical practice guidelines that emphasizes the consumption of plant protein foods to support public and planetary health. Soy is a high-quality plant protein food with a low environmental impact and cost that can play an important role in supporting these guidelines. As a result, there is a public health need to better understand and characterize soy isoflavones to support their consumption. In response, the authors of Effect of Soy Isoflavones on Measures of Estrogenicity: A Systematic Review and Meta-analysis of Randomized Controlled Trials evaluated the effect of soy isoflavones on postmenopausal women, using four measures of estrogenicity: endometrial thickness, vaginal maturation, levels of follicle-stimulating hormone (a hormone that regulates sexual development and reproduction), and circulating estradiol, the most common form of estrogen. These measures were chosen because they are known to be affected by the hormone estrogen and have been evaluated in several clinical trials involving soy isoflavones. The review was published in Advances in Nutrition—An International Review Journal, a publication of the American Society for Nutrition.

In order to conduct their research, the authors searched the scientific literature for relevant studies published up to August 2024, leading them to 40 randomized controlled trials, involving 3,285 women. Following their analysis of these trials, the authors concluded that “soy isoflavones do not exhibit estrogenic effects compared to non-isoflavone controls on four measures of estrogenicity in postmenopausal women.” Moreover, the results of this scientific review “provide a strong rationale for not assuming that soy isoflavones will exert health effects similar to the hormone estrogen.”

Although most of the controlled randomized trials in the authors’ analysis provided soy isoflavones as capsules, the results did not differ from trials in which soy isoflavones were provided in the form of soy protein-based beverages or foods. “However,” the authors noted, “because soy foods contain numerous biologically active components, whole soy foods may exert benefits beyond isoflavones alone on health outcomes, such as cholesterol for which soy protein has a health claim.”

In summary, this study demonstrates that soy and soy isoflavones are safe to consume: most notably, they are heart healthy and may alleviate menopausal symptoms. This conclusion may help alleviate some of the hesitancy women feel towards incorporating soy into their diets. Moreover, it supports dietary recommendations to consume more plant proteins to promote heart health, offering an environmentally sustainable alternative to animal-based proteins.

To help spread the word that soy and soy isoflavones are safe for postmenopausal women to consume, lead author Gabrielle Viscardi has developed an infographic under the aegis of the Nutritional Sciences Department of the University of Toronto. Health care providers and public health professionals are welcome to share this infographic with their patients and communities (also pictured below).