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Head-to-head evidence comparison — which supplement is right for you?
Probiotics wins 1 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
3 of 4 studies with measurable effects showed benefit.
Top outcomes
Verdict
Probably helps
18 of 26 studies with measurable effects showed benefit.
Top outcomes
100-200mg
Morning with coffee for focus, Evening for relaxation, As needed for stress
Suntheanine® capsules or powder
10-20 billion CFU
With or without food (strain-dependent), Same time daily for consistency
Capsules with multiple strains
30-60 minutes
30-60 minutes
30-60 minutes
Varies
2-4 weeks
4-8 weeks
4-8 weeks
First 1-2 weeks
The effects of L-theanine consumption on sleep outcomes: A systematic review and meta-analysis
Sleep medicine reviews (2025) · Meta analysis · n=897
The findings indicate the potential use of L-theanine in the management of sleep disturbances; however, the lack of studies on "pure" L-theanine warrants further investigation.
Efficiency of Different Supplements in Alleviating Symptoms of ADHD with or Without the Use of Stimulants: A Systematic Review
Nutrients (2025) · Systematic review
The evidence revealed the potential use of supplements as complementary ADHD treatments under clinical guidance.
Analysis of the Effects of Known Sleep-Support Supplements in Relation to Life Habits, Sleep Conditions, and Sleep Problems
Nutrients (2023) · Rct · n=160
All the tested supplements were found to ameliorate sleep problems significantly (Analysis 1).
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%.
Meta-analysis (n=897) and multiple RCTs support sleep benefits. Studies often used L-theanine in combination with other compounds, limiting pure L-theanine effect attribution. Effects include reduced sleep onset latency and improved subjective sleep quality.
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.
AI-estimated from published studies. Interpret as directional guidance.
Probiotics has a higher evidence score (9/10 vs 9/10) and wins in 1 of 3 categories.
For reduce anxiety & stress, L-Theanine has a higher relevance score (85 vs 52).
No known interactions between L-Theanine and Probiotics have been documented in our database. However, always consult a healthcare provider before combining supplements.