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Head-to-head evidence comparison — which supplement is right for you?
B-Complex vs Soy Isoflavones: B-Complex has the stronger overall evidence (6.5 vs 6/10); they're alternatives for cycle & hormonal symptoms — the best pick depends on your goals. Take the 60-second quiz for a pick tailored to your goals.
B-Complex wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Probably helps
5 of 8 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
12 of 14 studies with measurable effects showed benefit.
Top outcomes
1 capsule daily (per label)
Morning with breakfast
Methylated B-complex (methylcobalamin, methylfolate)
40-80mg isoflavones daily
Divided doses with meals, Consistent daily timing
Standardized soy isoflavone extract
and 1 more not shown
2-4 weeks
4-8 weeks
Immediate
4-12 weeks
6-12 months
8-12 weeks
Initial use
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.
A Comparative Study Evaluating the Effectiveness of Folate-Based B Vitamin Intervention on Cognitive Function of Older Adults under Mandatory Folic Acid Fortification Policy: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
Nutrients (2024) · Meta analysis · n=42768
The meta-analysis on the effects of folate-based B vitamin supplementation on cognitive function showed a significant overall impact (Z = 3.84; p = 0.0001; SMD, 0.18; 95% CI, 0.09, 0.28).
A Systematic Review and Meta-Analysis of B Vitamin Supplementation on Depressive Symptoms, Anxiety, and Stress: Effects on Healthy and 'At-Risk' Individuals
Nutrients (2019) · Meta analysis · n=2015
Regarding individual facets of mood, B vitamin supplementation benefited stress (n = 958, SMD = 0.23, 95% CI = 0.02, 0.45, p = 0.03).
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).
Multiple meta-analyses show small but statistically significant benefits for cognitive function in older adults and stroke prevention populations. Effect sizes are modest (SMD ~0.15-0.18). Benefits may be more pronounced in B-vitamin deficient populations.
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.
B-Complex has a higher evidence score (6.5/10 vs 6/10) and wins in 2 of 3 categories.
Both B-Complex and Soy Isoflavones score equally (85) for cycle & hormonal symptoms.
No known interactions between B-Complex and Soy Isoflavones have been documented in our database. However, always consult a healthcare provider before combining supplements.
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The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.