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Head-to-head evidence comparison — which supplement is right for you?
Niacin wins 1 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Probably helps
8 of 15 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
9 of 11 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (1)
Outcomes where both Niacin and Soy Isoflavones have evidence — compare verdict strength side-by-side.
500-2000mg daily for lipid effects; 50-500mg for general health
With food (reduces flush), Evening for lipid effects, Split doses for high amounts
Immediate-release niacin (nicotinic acid)
40-80mg isoflavones daily
Divided doses with meals, Consistent daily timing
Standardized soy isoflavone extract
4-8 weeks
4-8 weeks
30-60 minutes after dose
4-12 weeks
6-12 months
8-12 weeks
Initial use
Niacin for primary and secondary prevention of cardiovascular events
The Cochrane database of systematic reviews (2017) · Meta analysis · n=39195
Participants randomised to niacin were more likely to discontinue treatment due to side effects than participants randomised to control group (RR 2.17, 95% CI 1.70 to 2.77; participants = 33,539; studies = 17; I2 = 77%; moderate-quality evidence).
Effect of lipid-lowering therapies on lipoprotein(a) levels: a comprehensive meta-analysis of randomized controlled trials
Atherosclerosis (2025) · Meta analysis · n=145314
Among available LLTs, PCSK9mAbs, inclisiran, CETPi, and niacin significantly decreased Lp(a) levels.
A terminal metabolite of niacin promotes vascular inflammation and contributes to cardiovascular disease risk
Nature medicine (2024) · Meta analysis
Lastly, treatment with physiological levels of 4PY, but not its structural isomer 2PY, induced expression of VCAM-1 and leukocyte adherence to vascular endothelium in mice.
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 HDL increases. Higher doses increase discontinuation rates due to side effects (RR 2.17). Immediate-release forms have better lipid effects but more flushing.
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.
Niacin has a higher evidence score (9/10 vs 9/10) and wins in 1 of 3 categories.
For reduce inflammation, Niacin has a higher relevance score (85 vs 60).
No known interactions between Niacin and Soy Isoflavones have been documented in our database. However, always consult a healthcare provider before combining supplements.