Caffeine

Tier-SPublic-ready7/5/2026

Exercise performance and recovery is the main area connected here, and any felt benefit should be read together with the human evidence base.

Some human supplement-context evidence is present and directly informs the score.

Representative tier calculated from paper evidence that passed the collection audit.

Papers analyzed

Caution signal

Low

Representative score

85.2

Exercise performance and recoveryCognition, memory, and focusGlucose and metabolic health markers

Main benefit evidence

The representative ingredient tier is calculated from these target-level evidence groups.

Exercise performance and recovery

25 studiesTier-S

Exercise performance and recovery

Fairly consistent positive signal in studiesFelt benefit focusSupplement context

Potential benefit studied in Exercise performance and recovery.

Evidence score

85.0

Study context

Supplement context

This score reflects the strength of this benefit group. The ingredient tier also considers paper count, repetition, population, and study context.

Cognition and focus

3 studiesTier-B

Cognition, memory, and focus

Fairly consistent positive signal in studiesFelt benefit focusSupplement context

Potential benefit studied in Cognition and focus.

Evidence score

66.0

Study context

Supplement context

This score reflects the strength of this benefit group. The ingredient tier also considers paper count, repetition, population, and study context.

Glucose and metabolic health

1 studiesTier-C

Glucose and metabolic health markers

Some positive signal observedResearch marker focusSupplement context

This card is closer to a measured biomarker or lab outcome than a directly felt user benefit.

Evidence score

44.0

Study context

Supplement context

This score reflects the strength of this benefit group. The ingredient tier also considers paper count, repetition, population, and study context.

Skin, hair, and nails

1 studiesTier-C

Skin, hair, and nail support

Some positive signal observedFelt benefit focusPatient-group study

Potential benefit studied in Skin, hair, and nails. These findings come from a defined study population, so everyday effects may differ.

Evidence score

20.9

Study context

Patient-group study

This score reflects the strength of this benefit group. The ingredient tier also considers paper count, repetition, population, and study context.

Sleep

1 studiesTier-C

Stress Response and Sleep Changes

Some positive signal observedFelt benefit focusSupplement context

These findings come from stress response, cortisol, anxiety, or sleep outcomes. They may mix felt benefits with physiological markers.

Evidence score

20.9

Study context

Supplement context

This score reflects the strength of this benefit group. The ingredient tier also considers paper count, repetition, population, and study context.

Fatigue and energy

4 studiesTier-C

Fatigue and energy

Signal is still limitedFelt benefit focusSupplement context

Potential benefit studied in Fatigue and energy.

Evidence score

9.3

Study context

Supplement context

This score reflects the strength of this benefit group. The ingredient tier also considers paper count, repetition, population, and study context.

Recent research

Updated This Month10 new papers

Observed range in repeated studies

This range includes studies in specific patient groups. It is not a general dose or recommendation.

Lower observed study value

120

mg/day

3 independent studies

Higher observed study value

600

mg/day

Only ranges repeated in human, oral, single-ingredient studies are shown.

Not personal dosing instructions, recommendations, or safety limits.

Side effects and combination findings in studies

Findings from studies of this ingredient alone are separated from findings involving another supplement or medication.

Caution index

0.9

Caution band: Low

Caution signals

Side effects + combos + curated rules

Key precautions

No curated contraindication rule is available yet, but literature caution signals are shown below.

3 combo signals and 0 added-signal combos shown below.

These are signals reported in studies. They do not predict what will happen to an individual.

Findings to review with care

Side effects reported for the ingredient alone are separated from findings involving another supplement or medication.

Side effects reported when this ingredient was used alone

Symptoms or adverse events reported in studies of this ingredient without another active ingredient.

polymorphic broad complex QRS tachycardia1 papers

A case report of a 32-year-old woman who ingested 5000 mg of anhydrous caffeine, presenting with presyncope, agitation, polymorphic QRS tachycardia, metabolic acidaemia, and severe hypokalemia, treated successfully with intravenous propranolol.Human studies · Observational study

Positive combinations studied

Positive combination findings are separated by how the study compared the groups. This is not a recommendation to combine them.

Positive findings when used together

The combination had a positive result, but the contribution of each ingredient could not be separated.

비트루트 추출물In a randomized crossover trial of 20 healthy males, the combination of caffeine and beetroot juice significantly improved 1,000-m running performance compared to placebo (p < 0.01).

L-테아닌L-theanine combined with caffeine significantly reduced caffeine-induced tachycardia (17% vs 92%) and state anxiety compared to caffeine alone.

로디올라A randomized, double-blind, placebo-controlled trial in 48 male volleyball players found that combined Rhodiola rosea and caffeine supplementation significantly improved jump height, reduced power decline during high-frequency jumps, and lowered perceived exertion compared to placebo and single-agent groups.

Evidence summaries

Paper IDs and full lists are private. Only study types and summaries are shown.

Key Evidence #1

Public scholarly dataCitation signal: 523

review

[Abstract]: Following critical evaluation of the available literature to date, The International Society of Sports Nutrition (ISSN) position regarding caffeine intake is as follows: 1. Supplementation with caffeine has been shown to acutely enhance various asp

Key Evidence #2

Public scholarly dataCitation signal: 393

review

The evidence generally supports that consumption of up to 400 mg caffeine/day in healthy adults is not associated with overt, adverse cardiovascular effects, behavioral effects, reproductive and developmental effects, acute effects, or bone status and a shift

Key Evidence #3

Public scholarly dataCitation signal: 163

meta-analysis

[Abstract]: The authors prospectively examined whether caffeine intake was associated with lower risk of Parkinson disease (PD) in both men and women among 304,980 participants in the National Institutes of Health-AARP Diet and Health Study and whether smoking

3 more summariesLimited representative sample by study type.

Public scholarly dataCitation signal: 161

observational

[Abstract]: This study investigates the influence of habitual caffeine intake on aerobic exercise-performance responses to acute caffeine supplementation. A double-blind, crossover, counterbalanced study was performed. Forty male endurance-trained cyclists wer

Public scholarly dataCitation signal: 160

rct

[Abstract]: Caffeine increases cortisol secretion in people at rest or undergoing mental stress. It is not known whether tolerance develops in this response with daily intake of caffeine in the diet. We therefore tested the cortisol response to caffeine challe

Public scholarly dataCitation signal: 126

meta-analysis

[Abstract]: Caffeine is commonly consumed during pregnancy, crosses the placenta, with fetal serum concentrations similar to the mother's, but studies of birth outcome show conflicting findings. We systematically searched Medline and Embase for relevant public

Caffeine

Evidence score: 85.2|Caution index: 0.9

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