Caffeine: what the evidence actually shows
settled caffeine — well-studied; evidence and use are aligned
⚠ Safety in context
- minorwith L-Theanine: Commonly paired; L-theanine is said to smooth caffeine’s jitter. Low-stakes.
Evidence by outcome
cognitiongrade Ahigh certainty— reliably improves alertness, reaction time, and vigilance
energy / fatiguegrade Bmoderate certainty— reduces perceived fatigue; tolerance develops with regular use
strengthgrade Bhigh certainty— reliable ergogenic effect on power and endurance performance
cognitiongrade Dvery-low certainty— Cochrane review, 13 RCTs, shift-work context: memory/attention improved, no verbal-skill benefit; high risk of bias flagged; mostly young people in simulated conditions, not real shift workers.
What it probably doesn't do
- Caffeine for cognition — Grade D, Cochrane review, 13 RCTs, shift-work context: memory/attention improved, no verbal-skill benefit; high risk of bias flagged; mostly young people in simulated conditions, not real shift workers..
Grade history
- B → BCorrection by Claude (gold-standard provenance sweep): live Postgres source drift replaced with the verified seed source set [pmid-29876876] details →
- B → BCorrection by Claude (gold-standard provenance sweep): live Postgres source drift replaced with the verified seed source set [pmid-12204388] details →
- A → ACorrection by Claude (gold-standard provenance sweep): live Postgres source drift replaced with the verified seed source set [pmid-27612937] details →
Re-review cadence: every 12 months (Grade A/B) · next scheduled by · methodology v1.
By outcome — the money pages
Compare
- Caffeine vs Omega-3 for cognition
- Caffeine vs Creatine for cognition
- Caffeine vs Lion's Mane for cognition
- Caffeine vs Ginkgo for cognition
- Caffeine vs L-Theanine for cognition
- Caffeine vs Iron for cognition
- Caffeine vs Ashwagandha for cognition
- Caffeine vs Vitamin D for cognition
- Caffeine vs Turmeric for cognition
- Caffeine vs Rhodiola for cognition
- Caffeine vs Melatonin for cognition
- Caffeine vs Magnesium for cognition
- Caffeine vs NMN for energy / fatigue
- Caffeine vs Rhodiola for energy / fatigue
- Caffeine vs CoQ10 for energy / fatigue
- Caffeine vs Creatine for energy / fatigue
- Caffeine vs Iron for energy / fatigue
- Caffeine vs Vitamin B12 for energy / fatigue
- Caffeine vs Ashwagandha for energy / fatigue
- Caffeine vs Creatine for strength
- Caffeine vs Ashwagandha for strength
- Caffeine vs Vitamin D for strength
More
sources: PMID:27612937 · PMID:12204388 · PMID:29876876 · PMID:20464765
Cite this page
Reuse under CC-BY 4.0 with attribution to evidencebased.info.
Plain-text citation
Substrate. Caffeine: what the evidence actually shows. https://evidencebased.info/interventions/caffeine. Updated 2026-07-16.
BibTeX
@misc{substrate_nterventionscaffeine,
author = {Substrate editorial},
title = {Caffeine: what the evidence actually shows},
year = {2026},
url = {https://evidencebased.info/interventions/caffeine},
note = {evidencebased.info}
}