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Cocoa flavanols and global cognition: grade C

Limited evidence. Direction: No effect.

C LimitedIndustry-funded

Educational guidance, not medical advice

Why this grade

Rubric condition met: C, direction none: two COSMOS substudies in older adults (COSMOS-Mind n=2,262, 3 years; COSMOS-Clinic n=573, 2 years) were null on global cognition, their primary outcome, but they share one parent trial and are not independent

Two COSMOS substudies in older adults found no effect of 500 mg/day cocoa flavanols on global cognition composites, their primary outcome, and a 2026 meta-analysis of mixed populations found no benefit on the MMSE. Both substudies were preregistered and placebo-controlled; COSMOS was supported by a Mars Edge grant. Evidence is in older adults.

How we grade evidence

Studies this grade rests on

EffectMixedNo effectSize shows participants (n)202020252030Meta-analysisRCTArabpour 2026, 2026: meta-analysis, n = 2,847, result not recordedBaker 2023, 2023: RCT, n = 2,262, result not recordedVyas 2024, 2024: RCT, n = 573, result not recorded
each study this grade rests on, by publication year and design. Solid: effect versus the comparator; half-filled: mixed; hollow: no effect; dashed: result not recorded yet. Larger marks had more participants.
Show the numbers
StudyYearDesignParticipantsResult
Baker 20232023RCT2262result not recorded
Vyas 20242024RCT573result not recorded
Arabpour 20262026meta-analysis2847result not recorded

Effect of cocoa extract supplementation on cognitive function: results from the clinic subcohort of the COSMOS trial.

Vyas CM, Manson JE, Sesso HD. Effect of cocoa extract supplementation on cognitive function: results from the clinic subcohort of the COSMOS trial Am J Clin Nutr, 2024. PMID 38070683

Result not recorded
Design
Randomized, placebo-controlled trial, 2-year in-person cognitive subcohort of COSMOS (COSMOS-Clinic)
Sample
n = 573
Population
Adults aged 60 and over (mean age 69.6)
Funding
NIH grants (NHLBI, NIA, NEI, NCATS, WHI); Crossref funder list also names Mars Edge Cocoa Flavanol Science Hub

Effects of cocoa extract and a multivitamin on cognitive function: A randomized clinical trial.

Baker LD, Manson JE, Rapp SR. Effects of cocoa extract and a multivitamin on cognitive function: A randomized clinical trial Alzheimers Dement, 2023. PMID 36102337

Result not recorded
Design
Randomized, placebo-controlled 2x2 factorial pragmatic trial, 3 years (COSMOS-Mind)
Sample
n = 2,262
Population
Older adults (mean age 73), cognition tested by telephone
Funding
National Institute on Aging (R01AG050657); parent COSMOS trial supported by an investigator-initiated grant from Mars Edge (Mars, Inc.), including study pills

Effect of Chronic Dark Chocolate or Cocoa Intake on Cognitive Function: A Grading of Recommendations Assessment, Development, and Evaluation (GRADE)-Assessed Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Arabpour Z, Arabpour Z, Jazayeri S. Effect of Chronic Dark Chocolate or Cocoa Intake on Cognitive Function: A Grading of Recommendations Assessment, Development, and Evaluation (GRADE)-Assessed Systematic Review and Meta-Analysis of Randomized Controlled Trials Nutr Rev, 2026. PMID 42641106

Result not recorded
Design
Systematic review and meta-analysis of 16 randomized controlled trials (GRADE-assessed; PROSPERO CRD42024568294)
Sample
n = 2,847
Population
Adults in chronic cocoa or dark chocolate trials (mixed healthy, older and clinical samples per included trials)
Funding
Vice Chancellor for Research and Technology, Iran University of Medical Sciences (grant 30885)

Search and history

Search (): (cocoa[ti] OR flavanol*[ti]) AND (cognit*[tiab] OR memory[tiab]) AND randomized controlled trial[pt] AND humans[mh]

  • Graded N (proposed): Proposed in the monograph draft
  • N to C (proposed): Editor review ed-2026-11-11: Changed from N to C, direction none, after independent review finding F2: COSMOS-Mind and COSMOS-Clinic share the COSMOS randomization (NCT02422745), sponsor and investigators, so they are not 2 independent RCTs, and the 2026 meta-analysis is not restricted to the relevant population. The null result is stated plainly in the body. Older adults; industry-funded kept (2 of 3 Mars-linked). Owner may restore N by ruling that COSMOS substudies count as independent under the rubric.
  • C to C (approved): Editor sign-off November 13, 2026: grade matches the editor-approved final page