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Cocoa flavanols and blood pressure: grade B

Moderate evidence. Direction: Benefit.

B ModerateShort-term only

Educational guidance, not medical advice

Why this grade

Rubric condition met: Meta-analysis with high (unexplained) heterogeneity: Cochrane review of 35 RCTs, moderate-quality evidence

The Cochrane review (35 trials, 1,804 mainly healthy adults, 2-18 weeks) found a small reduction of about 2 mmHg compared with control, downgraded to moderate quality for unexplained heterogeneity; the effect was not significant in people with normal blood pressure. A 2026 Meiji-funded meta-analysis found a similar small effect. A 12-week trial by Mars, Inc. researchers of up to 2,000 mg/day in healthy adults found no change. The pooled reductions come from short-term trials; in a long-term COSMOS analysis (Mars Edge-supported, median 3.4 years) cocoa extract did not reduce new high blood pressure diagnoses overall.

How we grade evidence

Studies this grade rests on

EffectMixedNo effectSize shows participants (n)2015202020252030Meta-analysisRCTRied 2017, 2017: meta-analysis, n = 1,804, result not recordedSakuda 2026, 2026: meta-analysis, n = 1,167, result not recordedOttaviani 2015, 2015: RCT, n = 74, 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
Ottaviani 20152015RCT74result not recorded
Ried 20172017meta-analysis1804result not recorded
Sakuda 20262026meta-analysis1167result not recorded

Safety and efficacy of cocoa flavanol intake in healthy adults: a randomized, controlled, double-masked trial.

Ottaviani JI, Balz M, Kimball J. Safety and efficacy of cocoa flavanol intake in healthy adults: a randomized, controlled, double-masked trial Am J Clin Nutr, 2015. PMID 26537937

Result not recorded
Design
Open-label dose-escalation study (part 1) plus randomized, controlled, double-masked parallel trial, 12 weeks (part 2)
Sample
n = 74
Population
Healthy adults aged 35-55
Funding
not stated in PubMed record

Impact of cocoa flavanols on blood pressure and vascular function: an updated systematic review and meta-analysis of randomized controlled trials.

Sakuda M, Ito K, Adaniya Y. Impact of cocoa flavanols on blood pressure and vascular function: an updated systematic review and meta-analysis of randomized controlled trials J Nutr Health Aging, 2026. PMID 42679502

Result not recorded
Design
Systematic review and meta-analysis of 25 RCTs
Sample
n = 1,167
Population
Adults with normal or high blood pressure
Funding
Meiji Co., Ltd.

Effect of cocoa on blood pressure.

Ried K, Fakler P, Stocks NP. Effect of cocoa on blood pressure Cochrane Database Syst Rev, 2017. PMID 28439881

Result not recorded
Design
Cochrane systematic review and meta-analysis of 35 RCTs (40 treatment comparisons)
Sample
n = 1,804
Population
Mainly healthy adults, with or without high blood pressure
Funding
not stated in PubMed record

Search and history

Search (): (cocoa[ti] OR flavanol*[ti]) AND ("blood pressure"[tiab]) AND (meta-analysis[pt] OR systematic review[pt])

  • Graded B (proposed): Proposed in the monograph draft
  • B to B (approved): Editor sign-off November 13, 2026: grade matches the editor-approved final page