Soy and plant compounds reduce breast cancer recurrence

Research on breast cancer outcomes and phytonutrients.

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Soy isoflavones, part of soy compounds, could reduce breast cancer recurrence or death, according to a meta-analysis by Johns Hopkins. The study, reviewing 22 research papers globally, also investigated the impact of dietary intake of soybeans, lignans, cruciferous veggies, and green tea on breast cancer outcomes and overall mortality.

Soy isoflavones, especially at 60mg/day, may cut breast cancer recurrence by 26%, notably in post-menopausal survivors. Enterolactone, from lignans in plants like flaxseeds, reduces breast cancer-specific mortality by 28% and death by any cause by 31%, especially in post-menopausal women. The effective dose of lignans can’t be determined due to varying gut microbiomes affecting metabolism.

Lead study author Diana van Die, Ph.D., of NICM Health Research Institute at Western Sydney University, Australia, said, “These findings were graded probable, which means there is strong research showing that they contributed to the results we are seeing.”

The review found some suggestive results: green tea consumption may reduce breast cancer recurrence by 44%, especially with three to five cups daily. Lignans, consumed before breast cancer diagnosis, showed a non-significant 34% risk reduction in cancer-specific mortality for post-menopausal women but increased risk for pre-menopausal women. This hormonal dependency needs further investigation due to potential study biases.

Cruciferous veggies’ impact on breast cancer remains unclear due to low average intake. Research on soy, lignans, cruciferous veggies, and green tea, both before and after breast cancer diagnosis, didn’t yield a conclusive answer. Green tea and lignan studies focused on pre-diagnosis intake, while soy results considered pre- and post-diagnosis intake.

These studies focus on women who received medical treatment for breast cancer. Foods and phytonutrients are not treatment alternatives. The need for more robust studies arises to determine effective dosages and whether starting them after diagnosis has the same benefits as a lifelong dietary habit before diagnosis. This is crucial for patients seeking answers.

The research underscores the potential benefits of natural compounds derived from soy and other plants in reducing breast cancer recurrence and improving survival. However, further research is crucial to establish optimal dosages and understand the effectiveness of these compounds when introduced after a breast cancer diagnosis.

Journal reference:

  1. M Diana van Die, Kerry M Bone et al., Phytonutrients and outcomes following breast cancer: a systematic review and meta-analysis of observational studies. JNCI Cancer Spectrum. DOI: 10.1093/jncics/pkad104.

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