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Head-to-head evidence comparison — which supplement is right for you?
Soy Isoflavones vs Vitamin B6: Vitamin B6 has the stronger overall evidence (7 vs 6/10); 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.
Vitamin B6 wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
8 of 10 studies with measurable effects showed benefit.
Top outcomes
Verdict
Too few graded studies
1 of 2 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (1)
Outcomes where both Soy Isoflavones and Vitamin B6 have evidence — compare verdict strength side-by-side.
40-80mg isoflavones daily (a typical label dose, no cited trial of this supplement alone states a dose)
Divided doses with meals, Consistent daily timing
Standardized soy isoflavone extract
10-12mg daily (12 mg/day is the EU upper limit. Labels often give 25-100 mg, above it)
Morning with food, Can take with other B vitamins
P-5-P (Pyridoxal-5-Phosphate)
and 1 more not shown
4-12 weeks
6-12 months
8-12 weeks
Initial use
2-4 weeks
1-2 cycles
Months of high doses
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
The meta-analysis pooled 52 trials. The abstract gives no participant total.
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
We included 40 trials (52 trial comparisons, n = 3285) assessing the effect of a median reported dose of 75 mg/d of soy isoflavones in substitution for non-isoflavone controls over a median of 24 wk.
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).
Dosage exploration of combined B-vitamin supplementation in stroke prevention: a meta-analysis and systematic review
The American journal of clinical nutrition (2024) · Meta analysis · n=76664
In areas without and with partial folic acid fortification, combined B-vitamin supplementation significantly reduced the risk of stroke by 34% [RR: 0.66; 95% confidence interval (CI): 0.50, 0.86] and 11% (RR: 0.89; 95% CI: 0.79, 1.00), respectively.
Vitamin and mineral supplementation for maintaining cognitive function in cognitively healthy people in mid and late life
The Cochrane database of systematic reviews (2018) · Meta analysis · n=83000
28 trials with more than 83,000 participants. 14 trials with 27,882 participants compared folic acid, vitamin B12, vitamin B6, or a combination of these to placebo.
Drug Efficacy in the Treatment of Antipsychotic-Induced Akathisia: A Systematic Review and Network Meta-Analysis
JAMA network open (2024) · Meta analysis · n=492
No association between effect sizes and psychotic severity was found.
Vitamin B6 has a higher evidence score (7/10 vs 6/10) and wins in 2 of 3 categories.
For menopause support, Soy Isoflavones has a higher relevance score (90 vs 75).
No documented interaction was found in the data searched. This does not establish that this exact combination is safe.
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.