Regular cocoa intake modestly improves processing speed word fluency
STUDY: Arabpour Z et al, Nutr Rev 2026
STUDY TYPE: Systematic review and meta-analysis of randomized trials
FUNDING: Medical University
Background
Cocoa and dark chocolate are rich in flavanols, compounds that support brain health through antioxidant and vascular effects. This meta-analysis pooled that data to see which cognitive domains, if any, benefit.
The Study
- 16 trials (2,847 participants) reviewed qualitatively; 6 pooled, mostly healthy older or middle-aged adults
- Cocoa flavanol doses of roughly 65 to 993 mg/day, 4 weeks to several years
- Outcomes: Trail Making Test, verbal fluency, and the Mini-Mental State Examination
Results
Cocoa or dark chocolate sped up Trail Making Test completion, part A (5 seconds faster) and part B (13 seconds faster), and raised verbal fluency by about 3 words per minute versus placebo. Though these results stood up in the meta-analysis, the trials varied (heterogeneity high), and global cognition (MMSE) showed no benefit.
Effects were most robust with longer durations (at least 8 weeks) and higher doses (at least 500 mg flavanol daily).
Limitations
Only 6 of 16 eligible trials had usable data for pooling, and heterogeneity stayed largely unexplained. Few studies accounted for flavonoids from other foods, and most participants were cognitively healthy, so effects in impaired patients stay unclear. Trail Making part A finding lost significance when two trials were dropped in sensitivity testing.
Practice Implications
- Daily high-flavanol dark chocolate or cocoa (roughly 500 mg flavanol, meaning chocolate above 70% cocoa, not milk chocolate) for 8 weeks may have cognitive benefits, and other studies suggest mood benefits.
- But it is not without risks: Reflux, dental problems, and caffeine come to mind, and sugar content in diabetes.
- Learn more about a diet for mood that also improved ADHD and cognition.
—Chris Aiken, MD
Director, Psych Partners
Editor in Chief, Carlat Psychiatry Report
