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Pyrroloquinoline quinone

PQQ is a small molecule once thought to be a vitamin, although its actions in the human body are not related to this hypothesized vitamin-like mechanism. Via its actions as a REDOX agent in cells, it can modify signalling and is thought to support mitochondrial function.

Our evidence-based analysis on pyrroloquinoline quinone features 165 unique references to scientific papers.

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Summary of Pyrroloquinoline quinone

Primary information, health benefits, side effects, usage, and other important details

Pyrroloquinoline quinone (henceforth PQQ) is a small quinone molecule which has the ability to be a REDOX agent, capable of reducing oxidants (an antioxidant effect) and then being recycled by glutathione back into an active form. It appears to be quite stable as it can undergo several thousand cycles before being used up, and it is novel since it associates with protein structures inside the cell (some antioxidants, mostly notably carotenoids like β-carotene and astaxanthin, are located at specific areas of a cell where they exert proportionally more antioxidant effects due to proximity; PQQ seems to do this near proteins like carotenoids do so at the cell membrane).

The aforementioned REDOX functions can alter protein function and signalling pathways, and while there is a lot of promising in vitro (outside of a living model) research on what it could do there are only a few promising results of PQQ supplementation, mostly related to either altering some signalling pathways or via its benefits to mitochondria (producing more of them and increasing their efficiency).

It is a coenzyme in bacteria (so, to bacteria, this would be something like a B-vitamin) but this role does not appear to extend to humans. Since this does not extend to humans, the designation of PQQ as a vitamin compound has fallen through and it is only considered 'vitamin-like' at best.

PQQ seems to modify oxidation in a cell after binding to some proteins, and this modulatory role it plays can alter the signalling processes that go on in a cell. Due to PQQ being a REDOX agent (capable of both reducing and oxidizing) it is not a pure antioxidant, but it is involved in a cyclical antioxidative cycle with an antioxidant enzyme known as glutathione

For human evidence, the limited evidence we have right now suggests a possible neuroprotective role in the aged (no research in clinical situations of neurodegeneration nor in youth) and it may have an antiinflammatory role. This limited evidence also suggests that the main claim of PQQ, an enhancement of mitochondrial function, occurs in otherwise healthy humans given PQQ supplementation.

The animal evidence that might apply to humans (using oral supplementation at doses similar to what humans use) include a radioprotective effect, possible benefits to insulin resistance, and being a growth factor when PQQ is added to the diet over a long period of time. Higher than normal oral doses in rodents seem to also enhance peripheral neurogenesis (nerve growth outside of the brain) but not necessarily in the brain.

A large amount of the evidence for a direct antioxidant role or the neurological actions related to NMDA signalling of PQQ seem to use very high concentrations in cells, due to possible transportation issues to the brain and low concentrations of PQQ found in the blood following oral ingestion.

It holds a potential to modify signalling in humans, and although the oxidation in the blood (easiest thing to measure) in mostly unaffected it also retains the potential to act as an intracellular antioxidant. The enhancement of mitochondrial function may also occur, but beyond some alterations in signalling and the mitochondrial biogenesis most other properties of PQQ are unlikely to extend to humans

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How to Take

Recommended dosage, active amounts, other details

The optimal dosage of Pyrroloquinoline quinone (PQQ) to be taken daily is currently not known, but extrapolations from animal studies suggest that doses as low as 2mg are somewhat bioactive while most dietary supplements are sold in the 20-40mg range.

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Human Effect Matrix

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The Human Effect Matrix summarizes human studies to tell you what effects Pyrroloquinoline quinone has on your body, how much evidence there is, and how strong these effects are.

Full details are available to Examine members.
Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
grade-d Notable - See study
The decrease in C-reactive protein seen in one study in otherwise healthy humans reached 45% after three weeks of supplementation.
grade-d Minor - See study
A decrease in fatigue has been noted in older adults with self-reported energy problems
grade-d Minor - See study
IL-6 appeared to be significantly reduced in the serum of adults given PQQ supplementation relative to baseline.
grade-d Minor - See study
Although a decrease technically exists as assessed by TBARS, the decrease was measured at around 0.2% and is practically irrelevant.
grade-d Minor - See study
In persons with sleep disorders taking PQQ (which improved sleep) there were reductions in pain ratings at the end of the trial
grade-d Minor - See study
An improvement in sleep quality has been noted in persons with impaired sleep; it is not certain how PQQ affects persons with normal sleep cycles
grade-d Minor - See study
A reduction in self-reported stress has been noted after 8 weeks in persons with self-reported sleep problems; this study also noted improvements in sleep
grade-d Minor - See study
A decrease in urinary TMAO has been noted with supplementation of PQQ, which is thought to be due to increased activity of the FMO3 enzyme.
grade-d - - See study
Short term ingestion of PQQ supplementation in otherwise healthy adults has failed to significantly influence serum glucose concentrations.
grade-d - - See study
Overall oxidation in serum as assessed by TRAP has failed to be significantly influenced by PQQ supplementation in otherwise healthy adults.
grade-d - - See study
Three weeks supplementation of PQQ has failed to significantly influence HDL cholesterol levels in otherwise healthy adults.
grade-d - - See study
No apparent changes to LDL cholesterol exist in otherwise healthy adults given PQQ supplementation daily for up to three weeks.
grade-d - - See study
Serum ALT is not affected by supplementation of PQQ for up to three weeks.
grade-d - - See study
Short term supplementation of PQQ has failed to significantly influence triglycerides in otherwise healthy adults

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Things to Note

Is a Form Of

Other Functions:

Also Known As

PQQ, Methoxatin

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Click here to see all 165 references.