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Head-to-head evidence comparison — which supplement is right for you?
Probiotics wins 3 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
30 of 39 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
5 of 7 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (2)
Outcomes where both Probiotics and Tryptophan have evidence — compare verdict strength side-by-side.
10-20 billion CFU
With or without food (strain-dependent), Same time daily for consistency
Capsules with multiple strains
500-1000mg before bed
30-60 minutes before bed, On empty stomach or with carbohydrates
L-Tryptophan capsules
2-4 weeks
4-8 weeks
4-8 weeks
First 1-2 weeks
30-60 minutes
1-2 weeks
1-2 weeks
1-2 hours after dose
Preventive Effect of Probiotics on Oral Mucositis Induced by Cancer Treatment: A Systematic Review and Meta-Analysis
International journal of molecular sciences (2022) · Meta analysis · n=708
Three trials using Lactobacilli-based probiotics reported that the incidence of oral mucositis in the probiotic group was significantly low (risk ratio [RR] = 0.84, 95% confidence interval [CI] = 0.77−0.93, p = 0.0004).
Probiotics for treating acute infectious diarrhoea
The Cochrane database of systematic reviews (2020) · Meta analysis · n=12127
Effect size was similar in the sensitivity analysis and marked heterogeneity persisted.
Probiotics for the prevention of Clostridium difficile-associated diarrhea in adults and children
The Cochrane database of systematic reviews (2017) · Meta analysis · n=9955
A complete case analysis (i.e. participants who completed the study) among trials investigating CDAD (31 trials, 8672 participants) suggests that probiotics reduce the risk of CDAD by 60%.
The Tryptophan Catabolite or Kynurenine Pathway in a Major Depressive Episode with Melancholia, Psychotic Features and Suicidal Behaviors: A Systematic Review and Meta-Analysis
Cells (2022) · Meta analysis · n=4647
Severe patients showed significant lower (p < 0.0001) TRP (standardized mean difference, SMD = -0.517, 95% confidence interval, CI: -0.735; -0.299) and TRP/CAAs (SMD = -0.617, CI: -0.957; -0.277) levels with moderate effect sizes, while no significant difference in CAAs were found.
Comparative efficacy and tolerability of nutraceuticals for depressive disorder: A systematic review and network meta-analysis
Psychological medicine (2025) · Meta analysis · n=17437
Adjunctive nutraceuticals consistently showed better efficacy than antidepressants (ADT) alone in outcomes including SMD, remission, and response.
Differential Metabolites in Osteoarthritis: A Systematic Review and Meta-Analysis
Nutrients (2023) · Meta analysis · n=495
In the 13 studies, 132 kinds of small molecule differential metabolites were extracted, 58 increased, 57 decreased and 17 had direction conflicts.
Based on meta-analyses showing benefits for IBS and digestive symptoms. Effect sizes varied considerably between studies with low to very low certainty of evidence. Initial GI symptoms common when starting but typically resolve within 1-2 weeks.
Based on meta-analyses showing tryptophan's role in depression and serotonin pathways. Evidence comes from studies of tryptophan depletion and kynurenine pathway research rather than direct supplementation RCTs. Conservative effectiveness due to indirect evidence.
AI-estimated from published studies. Interpret as directional guidance.
Probiotics has a higher evidence score (9/10 vs 5.5/10) and wins in 3 of 3 categories.
For support mood, Tryptophan has a higher relevance score (75 vs 60).
No known interactions between Probiotics and Tryptophan have been documented in our database. However, always consult a healthcare provider before combining supplements.