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Caf9.5
Caffeine Research
Likely helps
982 peer-reviewed studies
What the evidence says
Likely helps
Caffeine appears to help in 27 of 33 studies with measurable effects — the evidence leans clearly favourable.
Most evidence is from high-quality meta-analyses and randomised trials published 2008–2026 with a typical study size of 99 participants.
Based on 979 studies · 151 meta-analyses · 693 RCTs · 277,475 total participants
Confidence
High confidence
What the studies found
27helped5unclear1didn't help· 946 more without graded effect data
By outcome
Cognitive functionEnhances short-term memory consolidation and recall · 30-60 minutes
However, aerobic responses to caffeine vary substantially, with time-trial performance ranging from ~-3% to +16%.
Data were pooled using standardized mean differences (SMDs) and 95% confidence intervals under random-effects models, and risk of bias was assessed using the Cochrane Risk of Bias tool.
Both low and moderate caffeine doses significantly reduced time-trial completion time relative to placebo.
In plain English: The relationship between caffeine intake and IBD risk varies by region, age, caffeine source, smoking, and education level.
Wu X et al. · Journal of gastroenterology and hepatology (2026)
No clear effect
← WorseNo effectBetter →
The meta-analysis showed no significant association between caffeine intake and IBD (RR = 0.84, 95% CI = 0.68-1.04).
In Americans, caffeine increased UC risk by 68% (RR = 1.68, 95% CI = 1.17-2.42).
Age analysis showed caffeine increased IBD risk by 4.52 times in those ≤18 (RR = 4.52, 95% CI = 1.59-12.88) but decreased risk by 7% in those >18 (RR = 0.93, 95% CI = 0.73-1.18).
4Fat oxidation rate during exerciseMeta-Analysisn=2,020 · very large study2020
In plain English: However, the fitness level of the participant may modulate the magnitude of the effect of caffeine on fat oxidation during exercise.
Collado-Mateo D et al. · Nutrients (2020)
Large benefit
← WorseNo effectBetter →
Likely real
A subsequent meta-analysis was performed using the random effects model to calculate the standardized mean difference (SMD).
The meta-analysis revealed that caffeine significantly (p = 0.008) increased the fat oxidation rate (SMD = 0.73; 95% CI = 0.19 to 1.27).
This increment was consistent with a significant (p = 0.04) reduction of the respiratory exchange ratio (SMD = -0.33; 95% CI = -0.65 to -0.01) and a significant (p = 0.049) increase in the oxygen uptake (SMD = 0.23; 95% CI = 0.01 to 0.44).
8Panic attacks in panic disorder patientsMeta-Analysisn=237 · medium study2022
In plain English: The results confirm that caffeine at doses roughly equivalent to 5 cups of coffee induces panic attacks in a large proportion of PD patients and highly discriminates this population from healthy adults.
Klevebrant L et al. · General hospital psychiatry (2022)
Huge benefit
← WorseNo effectBetter →
The 9 studies investigating panic attacks included 237 patients, of which 51.1% had a panic attack following caffeine, but none after placebo.
Six of these studies compared 128 patients with 115 healthy controls (HC), finding that patients (53.9%) were more vulnerable than HC (1.7%) for panic attacks following caffeine (log RR: 3.47; 95% CI 2.06-4.87).
Six studies investigated subjective anxiety in 121 patients and 111 HC following caffeine, with an overall effect indicating increased sensitivity to the anxiogenic effects of caffeine in the patient group (Hedges' g = 1.02 [95% CI: 0.09-1.96]).