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PQQ (pyrroloquinoline quinone) and executive function: grade C

Limited evidence. Direction: Benefit.

C LimitedIndustry-fundedShort-term only

Educational guidance, not medical advice

Why this grade

Rubric condition met: Two supplier-run placebo-controlled trials, one randomized and one of unreported size and design detail, one positive in an age subgroup (C)

The Ryusendo-funded trial reported better cognitive flexibility and executive function scores after 12 weeks than with placebo. In the Mitsubishi Gas Chemical trial, cognitive flexibility, processing speed and execution speed improved after 8 weeks in the 20 to 40 age group of an age-split analysis. Two industry-linked trials, one of unreported size and positive in a subgroup, give C.

How we grade evidence

Studies this grade rests on

EffectMixedNo effectSize shows participants (n)202020252030RCTControlled trialShiojima 2022, 2022: RCT, n = 64, result not recordedTamakoshi 2023, 2023: controlled trial, n not recorded, 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
Shiojima 20222022RCT64result not recorded
Tamakoshi 20232023controlled trialnot recordedresult not recorded

Pyrroloquinoline quinone disodium salt improves brain function in both younger and older adults.

Tamakoshi M, Suzuki T, Nishihara E. Pyrroloquinoline quinone disodium salt improves brain function in both younger and older adults Food Funct, 2023. PMID 36807425

Result not recorded
Design
Double-blind, placebo-controlled trial, 12 weeks
Population
Adults aged 20-65
Funding
not stated in the PubMed or Crossref record; full text not read. Authors affiliated with Mitsubishi Gas Chemical Company (PubMed affiliations).

Effect of Dietary Pyrroloquinoline Quinone Disodium Salt on Cognitive Function in Healthy Volunteers: A Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Study.

Shiojima Y, Takahashi M, Takahashi R. Effect of Dietary Pyrroloquinoline Quinone Disodium Salt on Cognitive Function in Healthy Volunteers: A Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Study J Am Nutr Assoc, 2022. PMID 34415830

Result not recorded
Design
Randomized, double-blind, placebo-controlled, parallel-group trial, 12 weeks
Sample
n = 64
Population
Healthy Japanese adults aged 40 to under 80 who felt more forgetful (58 completers, mean age about 71)
Funding
Ryusendo Co., Ltd. (Crossref funder); the first four authors list Ryusendo R&D affiliations

Search and history

Search (): pyrroloquinoline[tiab] AND (cognitive[tiab] OR memory[tiab] OR attention[tiab] OR cognition[tiab])

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