Loading…
We use essential cookies (authentication, your saved goals/stack) by default. With your permission we’ll also enable privacy-respecting analytics (Vercel Web Analytics, anonymous load-time metrics) and error-replay diagnostics (Sentry — DOM snapshots only when an error fires) so we can fix bugs faster. Learn more about cookies
Head-to-head evidence comparison — which supplement is right for you?
L-Lysine vs Soy Isoflavones: Soy Isoflavones has the stronger overall evidence (6 vs 5.5/10); they're alternatives for bone health — 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
Probably helps
4 of 6 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
8 of 10 studies with measurable effects showed benefit.
Top outcomes
500-3000mg daily; higher for active outbreaks
Empty stomach for better absorption, Divided doses throughout day, Away from high-arginine foods
L-Lysine HCl (capsules or powder)
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
and 1 more not shown
2-4 weeks prevention; acute treatment faster
4-8 weeks
Ongoing
4-12 weeks
6-12 months
8-12 weeks
Initial use
The Impact of Amino Acids on Postprandial Glucose and Insulin Kinetics in Humans: A Quantitative Overview
Nutrients (2020) · Systematic review
55 studies of acute amino acid ingestion or infusion in healthy adults and people with obesity or type 2 diabetes. L-lysine was one of 11 amino acids covered, and the abstract gives no result for lysine alone.
Nutraceuticals and phytoceuticals in the treatment of schizophrenia: a systematic review and network meta-analysis "Nutra NMA SCZ"
Molecular psychiatry (2025) · Meta analysis · n=2384
50 randomised trials (2,384 participants) of 22 add-on nutraceuticals in schizophrenia or schizoaffective disorder.
A Dietary Supplement in the Management of Patients with Lumbar Osteochondrosis: A Randomized, Double-Blinded, Placebo-Controlled Study
Nutrients (2024) · Rct · n=50
50 patients with lumbar osteochondrosis took a six-ingredient supplement (collagen type II, hyaluronic acid, N-acetyl-glucosamine, bamboo extract, L-lysine and vitamin C) or placebo for 3 months. Lysine was one ingredient.
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).
Soy Isoflavones has a higher evidence score (6/10 vs 5.5/10) and wins in 2 of 3 categories.
For bone health, Soy Isoflavones has a higher relevance score (75 vs 65).
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.