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Head-to-head evidence comparison — which supplement is right for you?
Black Cohosh vs Soy Isoflavones: Soy Isoflavones has the stronger overall evidence (6 vs 5/10); they're alternatives for menopause support — the best pick depends on your goals. Take the 60-second quiz for a pick tailored to your goals.
Soy Isoflavones wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
7 of 10 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
12 of 14 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (1)
Outcomes where both Black Cohosh and Soy Isoflavones have evidence — compare verdict strength side-by-side.
20-40mg standardized extract (1mg triterpene glycosides)
Morning and evening, With or without food
Standardized extract (2.5% triterpene glycosides)
40-80mg isoflavones daily
Divided doses with meals, Consistent daily timing
Standardized soy isoflavone extract
and 1 more not shown
4-8 weeks
4-8 weeks
4-8 weeks
4-12 weeks
6-12 months
8-12 weeks
Initial use
Black cohosh extracts in women with menopausal symptoms: an updated pairwise meta-analysis
Menopause (New York, N.Y.) (2023) · Meta analysis · n=2310
However, black cohosh did not significantly improve anxiety (Hedges' g = 0.194, 95% CI = -0.296 to 0.684, P = 0.438) or depressive symptoms (Hedges' g = 0.406, 95% CI = -0.121 to 0.932, P = 0.131).
Modulation of the hypothalamic-pituitary-adrenal (HPA) axis by plants and phytonutrients: a systematic review of human trials
Nutritional neuroscience (2022) · Systematic review
For most phytonutrients, the effects of supplementation on HPA-axis activity in humans is unclear.
Review & meta-analysis: isopropanolic black cohosh extract iCR for menopausal symptoms - an update on the evidence
Climacteric : the journal of the International Menopause Society (2021) · Meta analysis · n=43759
Effect sizes were larger when higher dosages of iCR as monotherapy or in combination with St.
Soy isoflavones prevent bone resorption and loss, a systematic review and meta-analysis of randomized controlled trials
Critical reviews in food science and nutrition (2020) · Meta analysis · n=5313
Soy isoflavones prevent osteoporosis-related bone loss in any weight status or treatment duration.
Effect of Soy Isoflavones on Measures of Estrogenicity: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
Advances in nutrition (Bethesda, Md.) (2025) · Meta analysis · n=3285
Addressing public health concerns may promote soy foods as high-quality plant protein sources with low environmental impact and cost, particularly benefiting postmenopausal women and aligning with sustainable dietary patterns and guidelines.
Effects of soy isoflavones on menopausal symptoms in perimenopausal women: a systematic review and meta-analysis
PeerJ (2025) · Meta analysis · n=533
In October 2024, we screened 2,099 articles, of which 12 were eligible for meta-analysis, and found that soy isoflavones were effective for treating menopausal symptoms (seven studies, 533 participants, Hedges' g = -0.25, 95% CI [-0.42 to -0.08], p = 0.00).
Based on multiple meta-analyses showing modest improvement in hot flashes. Isopropanolic extracts (iCR) showed most consistent effects. Effect sizes were larger at higher dosages but evidence shows only moderate benefit overall.
Meta-analysis of 533 participants showed effectiveness for menopausal symptoms. Effect size appears modest and heterogeneity was noted across studies. Individual response varies significantly.
AI-estimated from published studies. Interpret as directional guidance.
Soy Isoflavones has a higher evidence score (6/10 vs 5/10) and wins in 2 of 3 categories.
For menopause support, Soy Isoflavones has a higher relevance score (90 vs 58).
No known interactions between Black Cohosh and Soy Isoflavones have been documented in our database. However, always consult a healthcare provider before combining supplements.
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.