Bio PQQ

Pharmacology & Research

Pyrroloquinoline quinone (PQQ, methoxatin) is a small, water-soluble redox-cycling quinone that acts as a cofactor and antioxidant. It was first isolated from bacterial alcohol dehydrogenase in 1979 and later found in human tissue, breast milk and many plant foods; it is not an established human vitamin, but it is a bioactive dietary factor with real mechanistic pharmacology (mitochondrial biogenesis, radical scavenging, nerve-growth-factor induction) ^{6Reference 6Rucker et al. · 2009ReviewPotential physiological importance of pyrroloquinoline quinone — [review]View study →}. The human evidence is dominated by small, short (8–12 week), often industry-sponsored trials of the disodium salt (BioPQQ / mnemoPQQ), concentrated on cognition, fatigue/sleep and mitochondrial markers. Effects are real in mechanism but modest and inconsistently replicated in people, and — unlike a mineral or vitamin — there is no deficiency state to correct, so benefits are “extra on top of adequacy” rather than repletion. Only one supplemental form (the disodium salt) has been studied in almost all human trials, so bioavailability caveats are minor but the funding and sample-size caveats are large.

1. Cognition & memory

The lead human evidence is a randomized, double-blind, placebo-controlled trial in 41 healthy elderly subjects given 20 mg/day of PQQ disodium salt (BioPQQ) for 12 weeks, reporting improved selective attention (Stroop) and some memory measures versus placebo ^{1Reference 1Itoh et al. · 2016RCTEffect of the antioxidant supplement pyrroloquinoline quinone disodium salt (BioPQQ) on cognitive functions — [randomized controlled trial]View study →}. A larger double-blind parallel-group trial of the disodium salt in healthy volunteers similarly reported gains in memory and, on stratified analysis, faster improvement in cognitive flexibility and executive speed in younger adults (20–40 y) ^{2Reference 2Shiojima et al. · 2022RCTEffect of dietary pyrroloquinoline quinone disodium salt on cognitive function in healthy volunteers: a randomized, double-blind, placebo-controlled, parallel-group study — [RCT]View study →}. A 2024 narrative review from the manufacturer’s laboratory summarizes improvements across general, verbal and working memory and attention, but the trials are small, short and predominantly industry-affiliated ^{7Reference 7Ikemoto et al. · 2024ReviewThe effects of pyrroloquinoline quinone disodium salt on brain function and physiological processes — [review]View study →}.

Gap: trials are small (tens of subjects), 8–12 weeks, and mostly funded or staffed by the disodium-salt manufacturers; independent replication in larger cohorts is lacking.

2. Oxidative-stress markers

PQQ is a genuine redox-cycling antioxidant in vitro, protecting against lipid peroxidation ^{10Reference 10Miyauchi et al. · 1999In vitroAction of pyrroloquinolinequinol as an antioxidant against lipid peroxidation in solution — [in vitro]View study →}. In a human crossover study of 10 subjects, PQQ ingestion changed antioxidant potential and lowered plasma lipid-peroxide/TBARS indicators of oxidative stress ^{3Reference 3Harris et al. · 2013Clinical trialDietary pyrroloquinoline quinone (PQQ) alters indicators of inflammation and mitochondrial-related metabolism in human subjects — [crossover study]View study →}. Reviews and the 2024 summary note that PQQ ingestion lowers blood lipid-peroxide levels in humans, consistent with antioxidant activity ^{7Reference 7Ikemoto et al. · 2024ReviewThe effects of pyrroloquinoline quinone disodium salt on brain function and physiological processes — [review]View study →}.

Gap: these are surrogate blood-marker changes in very small samples, not clinical outcomes; whether lower lipid peroxides translate to health benefit is unproven.

3. Fatigue, sleep & mood

Short trials of the disodium salt report self-reported improvements in fatigue, sleep quality, appetite and mood alongside the cognitive endpoints ^{2Reference 2Shiojima et al. · 2022RCTEffect of dietary pyrroloquinoline quinone disodium salt on cognitive function in healthy volunteers: a randomized, double-blind, placebo-controlled, parallel-group study — [RCT]View study →}, and reviews cite PQQ for physiological and quality-of-life measures ^{7Reference 7Ikemoto et al. · 2024ReviewThe effects of pyrroloquinoline quinone disodium salt on brain function and physiological processes — [review]View study →}. These endpoints are subjective and secondary in most designs.

Gap: endpoints are self-reported and secondary; no large, independent, pre-registered sleep or fatigue trial confirms a dedicated effect.

4. Mitochondrial biogenesis / inflammation

The mechanistic case is strong in animals and cells: PQQ stimulates mitochondrial biogenesis via PGC-1α/CREB signalling in cell culture ^{4Reference 4Chowanadisai et al. · 2010In vitroPyrroloquinoline quinone stimulates mitochondrial biogenesis through CREB phosphorylation and increased PGC-1α — [in vitro]View study →}, and dietary PQQ alters inflammation and mitochondrial-related metabolism ^{3Reference 3Harris et al. · 2013Clinical trialDietary pyrroloquinoline quinone (PQQ) alters indicators of inflammation and mitochondrial-related metabolism in human subjects — [crossover study]View study →}. In the 10-subject human crossover, PQQ shifted urinary metabolites tied to mitochondrial function and lowered inflammatory markers (CRP, IL-6) ^{3Reference 3Harris et al. · 2013Clinical trialDietary pyrroloquinoline quinone (PQQ) alters indicators of inflammation and mitochondrial-related metabolism in human subjects — [crossover study]View study →}. This is the biological rationale behind most marketing, but human confirmation is limited to markers.

Gap: human data are one small crossover measuring biomarkers, not mitochondrial function or clinical energy outcomes; the effect on people’s “energy” is inferred, not demonstrated.

5. Exercise / ergogenic

Because endurance exercise and PQQ share mitochondrial-biogenesis pathways, PQQ was proposed as ergogenic. A 6-week randomized trial gave 20 mg/day to untrained men during endurance training and found PQQ did not meaningfully improve aerobic performance or add to training-induced mitochondrial-biogenesis markers beyond exercise alone ^{8Reference 8Hwang et al. · 2020RCTEffects of pyrroloquinoline quinone (PQQ) supplementation on aerobic exercise performance and indices of mitochondrial biogenesis in untrained men — [RCT, largely null]View study →}.

Gap: the best available human performance trial is essentially null; the mitochondrial mechanism did not translate into ergogenic benefit.

Mechanisms

Target / pathway	Effect	Relevant to
Redox cycling (quinone/quinol)	Scavenges superoxide/peroxyl radicals; recyclable antioxidant	Oxidative-stress markers 10Reference 10Miyauchi et al. · 1999In vitroAction of pyrroloquinolinequinol as an antioxidant against lipid peroxidation in solution — [in vitro]View study →
PGC-1α / CREB signalling	Upregulates mitochondrial biogenesis	Mitochondrial / energy claims 4Reference 4Chowanadisai et al. · 2010In vitroPyrroloquinoline quinone stimulates mitochondrial biogenesis through CREB phosphorylation and increased PGC-1α — [in vitro]View study →
Nerve growth factor (NGF) synthesis	Stimulates NGF production/secretion in astroglial cells (in vitro)	Neuroprotection claims 5Reference 5Murase et al. · 1993In vitroStimulation of nerve growth factor synthesis/secretion in mouse astroglial cells by coenzymes (PQQ) — [in vitro]View study →
NF-κB / inflammatory signalling	Lowers CRP, IL-6 in small human data	Inflammation markers 3Reference 3Harris et al. · 2013Clinical trialDietary pyrroloquinoline quinone (PQQ) alters indicators of inflammation and mitochondrial-related metabolism in human subjects — [crossover study]View study →
Quinoprotein cofactor (bacterial)	Cofactor for alcohol/glucose dehydrogenases (not confirmed in humans)	Historical / classification

Pharmacokinetics

PQQ (as the disodium salt) is water-soluble and orally absorbed; human dosing studies use single oral doses around 0.2 mg/kg and daily supplementation of 20 mg. Plasma and urinary PQQ rise measurably after ingestion and clear within roughly 48 hours, indicating a relatively short residence with renal excretion ^{3Reference 3Harris et al. · 2013Clinical trialDietary pyrroloquinoline quinone (PQQ) alters indicators of inflammation and mitochondrial-related metabolism in human subjects — [crossover study]View study →}. There is no established storage pool or defined human requirement. Because almost all human trials use the same disodium-salt form, form-specific bioavailability differences are not a major practical variable here — unlike minerals.

Clinical trials

Registered and published human trials are few and small, largely sponsored by manufacturers of the disodium salt (Mitsubishi Gas Chemical / BioPQQ; Ryusendo / mnemoPQQ); most preclinical work is in rodents and cell culture, and PQQ is off the radar of large independent trial programmes.

Last checked: July 2026.

Dietary Sources

PQQ is not made in meaningful amounts by the human body but is widespread at low levels in the diet and in human breast milk, so most people already have a small baseline intake. Reported dietary intakes are on the order of a few milligrams per day at most — far below the 20 mg used in supplement trials.

Food	Approx. PQQ content
Fermented soy (natto)	Among the richest sources
Parsley, green pepper	Relatively high (µg per gram)
Kiwifruit, papaya	Moderate
Green tea, oolong tea	Moderate (per serving)
Tofu, spinach	Lower
Human breast milk	Present — notable for infant intake

Levels vary widely by assay and food, and early reports of very high egg/skim-milk content were not confirmed. Ordinary diets supply roughly micrograms-to-low-milligrams per day; the supplemental 20 mg dose is far above dietary exposure ^{11Reference 11Kumazawa et al. · 1995Levels of pyrroloquinoline quinone in various foods — [food-composition analysis]View study →}.

Dosage & Intake

There is no RDA, AI or Tolerable Upper Intake Level for PQQ — it is not classified as an essential human nutrient. Human trials almost universally use 20 mg/day of PQQ disodium salt (BioPQQ / mnemoPQQ), with some protocols around 10 mg/day; single-dose pharmacokinetic work used ~0.2 mg/kg. PQQ is water-soluble and typically taken once daily; there is no established need for split dosing (unlike minerals, where fractional absorption falls with dose). Because the disodium salt is the form in nearly all studies, “PQQ” on a label almost always means this form, so compound-vs-elemental weight distinctions are minor.

These are doses studied in research, not a personal recommendation.

Safety

PQQ disodium salt is well tolerated in short human trials at 20 mg/day, with no consistent pattern of serious adverse effects reported over 8–12 weeks. The dose-limiting concerns come from animal toxicology: a subchronic rat study identified kidney effects at high doses, and GLP safety studies put the rat oral LD50 in the ~1,400–1,800 mg/kg range — i.e. adverse effects appear only at exposures orders of magnitude above the human 20 mg dose ^{12,13Reference 12Shiojima et al. · 2022Safety assessment of a novel dietary pyrroloquinoline quinone disodium salt (mnemoPQQ) — [GLP toxicity study]View study →Reference 13Liang et al. · 2015AnimalA subchronic oral toxicity study on pyrroloquinoline quinone (PQQ) disodium salt in rats — [animal toxicology]View study →}. No drug interactions of clinical significance are established; theoretical interactions (e.g. with other redox-active supplements) have not been formally assessed.

Pregnancy & lactation

Verdict: avoid / not established. PQQ occurs naturally in breast milk, but there are no human safety trials of supplemental PQQ in pregnancy or lactation. Because supplemental doses greatly exceed dietary/breast-milk exposure and long-term data are absent, supplementation is not recommended during pregnancy or breastfeeding without clinician guidance.

Scope of this safety review (for honesty, not a claim):

• Interactions assessed? No — no formal human drug-interaction studies; only theoretical considerations.
• Pregnancy/lactation assessed? No — no supplemental-dose human trials; natural presence in breast milk does not establish supplement safety.
• Upper Limit? No UL set — the absence of a UL does not imply unlimited intake is safe; long-term human safety above 20 mg/day is untested.

References