← Surfer · The Kit · Coach hub
Coach — PQQ (inventory, not flux)
An old bacterial cofactor that never became a vitamin may ask a cell's nucleus to build more mitochondria. That is a request for more machinery tomorrow, not more energy this afternoon, and in people it has not yet been measured.
Pyrroloquinoline quinone, mercifully shortened to PQQ, arrives in the supplement aisle wearing the most tired label available: antioxidant. The working hypothesis here finds that label the least interesting thing about it. Many molecules quench free radicals, and most of them do nothing to the number of mitochondria in a cell. The more interesting reading is that PQQ, in the systems where it has been properly tested, works as a signal: a transcriptional request for more respiratory machinery. Whether that request is honored in a human body is the open question this essay keeps in view.
Cautions first
Because PQQ is sold freely, it is worth starting with what the evidence does not support. The extended report is plain: "It is not medical advice, a treatment protocol, or a recommendation for self-administration. Pyrroloquinoline quinone is not an approved drug. Human evidence for mitochondrial biogenesis is absent. Cognitive trials are small, short, and often industry-linked. The European Food Safety Authority has assessed a disodium salt for food-supplement use at 20 mg/day in healthy adults, excluding pregnant and lactating women; that assessment is not a claim of efficacy, and it does not clear use in children or in kidney disease. Any use requires individual medical evaluation."
On kidneys and pregnancy it adds: "Pregnant and lactating women were excluded from the intended use. High-dose animal studies found urinary crystals and protein that informed the no-effect level; the human trials did not comprehensively assess kidney function. That is a reason for caution in known kidney disease."
This essay gives no dose. The amounts used in published trials are reported in the extended report as citation context only, not as a personal recommendation.
A cofactor that never became a vitamin
PQQ began as an unnamed helper molecule in bacteria. In 1964 a researcher studying a bacterial sugar-processing enzyme described a third redox cofactor alongside the familiar ones built from niacin and riboflavin. In 1979 two groups independently extracted it and solved its structure. Bacteria use it in enzymes that mammals do not have, and mammals have no dedicated PQQ enzyme of their own.
In 2003 a paper in Nature announced that PQQ was a new vitamin, tied to an enzyme in the breakdown of the amino acid lysine. The claim did not survive. Within two years other researchers showed that the markers the vitamin argument required did not move with PQQ intake, and that the database matches used to find a mammalian binding site were mislabeled. A vitamin is something an animal cannot make and cannot do without, attached to an enzyme that fails in its absence. PQQ did not meet that standard.
What the deprivation research does show is narrower and more useful. Mice raised on carefully defined diets very low in PQQ grow with fewer mitochondria and lower activity of mitochondrial genes, and putting it back restores both. Accessory factor is the right name. Vitamin is not.
Food contains PQQ in tiny amounts, measured in billionths of a gram per gram, highest in natto, parsley, green pepper, kiwi, and spinach. The European safety assessment judged the supplement amount it reviewed to be at least 250 times the estimated intake from food. A bowl of natto is not the intervention the trials tested, and the hypothesis has to be stated at the pharmacological level or it becomes a different idea.
Inventory, not flux
PQQ cycles between an oxidized and a reduced form and is not used up in the process, which makes it catalytic. Two mechanisms earn attention.
The first is a possible bridge to NAD. Researchers have reported that PQQ binds an enzyme called lactate dehydrogenase and speeds the conversion of NADH back to NAD. If that happens in living tissue, it would nudge the cell toward the state that the sirtuins, enzymes central to the fasting and exercise response, depend on. The extended report grades this honestly: "The bridge is the right kind of bridge. It is not yet a demonstrated one in people."
The second mechanism is the one the hypothesis actually stands on. In a 2010 study, mouse liver cells exposed to PQQ for a day or two showed more mitochondrial enzyme activity, more mitochondrial DNA, and more respiration. Upstream, a switch protein called CREB was activated and the master regulator of mitochondrial building, PGC-1-alpha, rose. When researchers silenced CREB or PGC-1-alpha, the increase disappeared. That is a necessary-pathway experiment: it shows not just that something happened but which route it required. The CREB signal faded within hours, as a signal should, while the change in mitochondria took a day or two, as a building program should.
There is no known PQQ receptor in mammals. The proposed trigger is the redox cycling itself, which can make a small amount of hydrogen peroxide. At that level, peroxide is a signal, the same kind of signal working muscle uses, rather than damage. Calling PQQ an antioxidant inverts the order. The useful event, if the cell data are right, is a controlled oxidation that the nucleus reads as permission to build.
What PQQ does not do deserves equal weight. It does not bypass the damaged parts of the energy chain. It does not hand electrons to the chain's carriers. A cell that needs electrons moved this afternoon will not get them from PQQ.
Methylene blue is a different layer
PQQ and methylene blue are both catalytic redox molecules, and that is where the resemblance ends. Methylene blue works on flow through the chain a cell already has, shuttling electrons around congested segments within minutes. PQQ works on inventory, asking for more chain to be built over a day or two. If methylene blue is a jumper cable on the engine already installed, PQQ is a work order sent to the factory. A work order does not start a stalled engine this afternoon.
Their safety profiles differ as sharply. Of methylene blue, the extended report says: "The cost is real: monoamine oxidase A inhibition, a serotonergic interaction, a G6PD exclusion." Of PQQ it says: "The molecule is not a monoamine oxidase inhibitor. It is not a serotonergic precipitant. G6PD deficiency is not a described exclusion." And it is explicit that "Methylene blue is a drug; any methylene blue use is physician-guided, and this page gives no methylene blue dosing." Methylene blue appears in this essay only as a comparison.
What the human evidence actually measures
The human record is smaller than the marketing, and it measures different things. A crossover study of ten adults over three days found falls in two inflammatory markers and a shift in urinary metabolites, with no tissue biopsy and no count of mitochondria. An open-label trial of seventeen adults over eight weeks reported better mood, fatigue, and sleep scores, without a placebo group. A combination trial paired PQQ with CoQ10, so its effects cannot be assigned to PQQ alone.
The cleanest study randomized sixty-four healthy adults aged forty to under eighty who felt they were growing more forgetful; fifty-eight finished twelve weeks. The PQQ group improved on several memory, attention, and processing-speed measures, with no adverse events recorded. The ingredient supplier was involved, and mitochondrial measures were not taken. A change at twelve weeks fits a building program, but it also fits better sleep, less inflammation, or expectation. A small trial in older adults with mild cognitive impairment combined PQQ with hydrogen-producing magnesium, so it is not a PQQ trial at all.
The grade, stated once: building of mitochondria is shown in mouse liver cells and inferred from deprivation and repletion in mice. No published randomized trial has shown the rise in human muscle or blood-cell mitochondrial DNA that the marketing sentence requires. The extrapolation is reasonable. It is not a result.
Where it would fit, if anywhere
The hypothesis places PQQ on the inventory side of strength, and only after the basics. Physical load is the body's own work order for more mitochondria. Fasting windows and sleep set the conditions in which a new unit is worth building. Clearance matters too: printing new mitochondria without retiring failed ones adds mass without necessarily adding function, and PQQ is not a signal for clearance. The essays on biogenesis and mitophagy cover those halves.
On timing, the extended report is provisional. Trials gave it once daily, sometimes after breakfast, a compliance habit rather than a mechanism. Its own summary is the right one: "Do not time pyrroloquinoline quinone as if it were the dye. Do not expect it to occupy a chain this afternoon." There is no evidence at studied amounts that it blunts the benefit of training, and no evidence that it adds anything on top of training that is already working.
A person whose problem is sleep debt and insulin resistance does not have a PQQ deficiency. A person whose problem is a measured failure of the energy chain does not have a building deficiency as the first problem. Diet, light, sleep, and load remain first. The eye, too, is tempting to borrow from the methylene blue literature, since the retina is so dense with mitochondria. PQQ protects cultured cells against chain poisons, which is a reason to predict protection, not a treatment for any eye disease and not a substitute for pressure control in glaucoma.
Questions worth bringing to a physician
If PQQ is on someone's mind, the useful questions are simple. Is building more mitochondria actually the limiting factor, once diet, light, sleep, and load are in order, or is the real problem sleep debt, insulin resistance, or something else? Is there pregnancy, breastfeeding, a child, or known kidney disease, where the European assessment does not clear use? Is methylene blue also in the picture, and if so, is its prescribing physician aware of everything else being taken? And what would count as a result for this person, given that no human trial has measured a mitochondrial marker?
The honest summary
PQQ is a cofactor bacteria still use, which a mammalian nucleus can, in one well-designed cell experiment, read as permission to build mitochondria. The permission is shown in a liver cell and inferred in a deprived mouse. It is not shown in a human biopsy. The cognitive studies are real and small. The antioxidant sentence is a distraction. A work order for more of the machine is not the same act as keeping electrons moving on the machine you already have.
For the full history, mechanism, and trial details, read the extended report on PQQ. The essays on NAD precursors and CoQ10 cover neighboring cofactors, the extended report on strength describes the pillar PQQ would sit in, and the short version is in the lessons.
A working hypothesis, open to correction and revised as new evidence arrives. Last revised October 17, 2026.
Related: Sage · Strength Coach · Biogenesis Coach · Methylene Blue Coach · NAD precursors Coach · CoQ10 Coach · Surfer Kit card · Fuchs’ Dystrophy Coach
See the notice at the top of this page. Working hypothesis, not medical advice and not a dosing recommendation. Pyrroloquinoline quinone is not an approved drug. Any use requires individual medical evaluation. Any methylene blue use is physician-guided.