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Si6.0
Soy Isoflavones Research
Likely helps
271 peer-reviewed studies
What the evidence says
Likely helps
Soy Isoflavones appears to help in 10 of 13 studies with measurable effects — the evidence leans clearly favourable.
Most evidence is from high-quality meta-analyses and randomised trials published 1992–2026 with a typical study size of 421 participants.
Based on 271 studies · 54 meta-analyses · 202 RCTs · 23,402 total participants
Confidence
High confidence
What the studies found
10helped3unclear· 258 more without graded effect data
By outcome
Women's healthMay help manage menopausal symptoms like hot flashes and mood changes · 4-8 weeks · Supports healthy estrogen metabolism and hormonal equilibrium · 4-8 weeks · May help reduce menstrual discomfort and PMS symptoms · 1-3 cycles
Likely helps253 studies
Cholesterol & lipids
Probably helps48 studies
Bone healthSupports bone mineral density and skeletal strength · 8-12 weeks
Skin healthImproved fine lines in postmenopausal RCTs (estrogenic effect) · 12-24 weeks · Improved skin elasticity in postmenopausal women · 12-24 weeks
Mostly mechanism / observational3 studies
Depression & moodReduced hot flashes and menopausal symptoms · 4-12 weeks
Too few graded studies1 study
By the numbers
Pulled from 35 studies with measurable effects
Likely real effects
78%
across studies
People studied
23k
typical study: 421 people
Strongest designs
256
54 pooled, 202 randomised
Showed benefit
77%
10/13 studies
How long studies ran
1–3 months
1
Populations Studied
Menopausal women6
Postmenopausal women5
Cancer patients2
Women with polycystic ovary syndrome1
Steady research
52 studies in the last 5 years · Latest meta-analysis: 2025
199220092026
1PCOS symptoms improvementMeta-AnalysisCited 2×n=5,501 · very large study2025
Chromium, inositol, and Omega-3 were found to be beneficial for improving lipid profile.
Zhao G et al. · Reproductive biology and endocrinology : RB&E (2025)
Inositol significantly decreased total cholesterol and triglyceride levels, while curcumin was most effective in improving low-density and high-density lipoprotein cholesterol levels.
Chromium, inositol, and Omega-3 were found to be beneficial for improving lipid profile.
For improving obesity, sex hormone levels, inflammatory factors and oxidative stress indicators of PCOS patients, carnitine, chromium, and soy isoflavones are effective options, respectively.
2Measures of estrogenicityMeta-AnalysisCited 7×n=3,285 · very large study2025
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 ...
Viscardi G et al. · Advances in nutrition (Bethesda, Md.) (2025)
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.
This study was registered in PROSPERO as CRD42023439239.
3Systematic ReviewCited 16×n=3,254 · very large study2025
There is some evidence to support the use of nutritional interventions for improving psychological symptoms of PMS.
Robinson J et al. · Nutrition reviews (2025)
There is some evidence to support the use of nutritional interventions for improving psychological symptoms of PMS.
However, more research using consistent protocols, procedures to minimize risk of bias, intention-to-treat analysis, and clearer reporting is required to provide conclusive nutritional recommendations for improving PMS-related psychological outcomes.
4Menopausal symptomsMeta-AnalysisCited 3×n=533 · large study2025
More trials should be conducted in the future to validate our findings.
Luan H et al. · PeerJ (2025)
Noticeable benefit
← WorseNo effectBetter →
Likely real
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).
However, our results should be interpreted with caution owing to the small sample size.
More trials should be conducted in the future to validate our findings.
5Non-alcoholic fatty liver disease parametersMeta-AnalysisCited 64×n=2,173 · very large study2022
Based on current evidence, curcumin can reduce BMI, TG, TC, liver enzymes, and insulin resistance; catechin can reduce BMI, insulin resistance, and TG effectively; silymarin can reduce liver enzymes.
Yang K et al. · Frontiers in immunology (2022)
Based on current evidence, curcumin can reduce BMI, TG, TC, liver enzymes, and insulin resistance; catechin can reduce BMI, insulin resistance, and TG effectively; silymarin can reduce liver enzymes.
For resveratrol, naringenin, anthocyanin, hesperidin, and catechin, more RCTs are needed to further evaluate their efficacy and safety.
7Fasting blood glucoseMeta-AnalysisCited 35×n=1,529 · large study2016
Although the results displayed a significant tendency in favor of soy isoflavones, it appears that genistein alone played an important role in improving glucose metabolism due to its low heterogeneity.
Fang K et al. · Molecular nutrition & food research (2016)
Noticeable benefit
← WorseNo effectBetter →
The overall results showed that the average difference in fasting blood glucose values between women assigned to soy isoflavones and women in placebo groups was -0.22 mmol/L (95% CI: -0.38 to -0.07 mmol/L) under a random-effects model.
In addition, the effect of soy isoflavones on insulin was also significant: -0.43 μIU/mL (95% CI: -0.71 to -0.14 μIU/mL), as was the effect on homeostasis model assessment insulin resistance (HOMA-IR): -0.52 (95% CI: -0.76 to -0.28).
Although the results displayed a significant tendency in favor of soy isoflavones, it appears that genistein alone played an important role in improving glucose metabolism due to its low heterogeneity.