What Is PQQ? A Simple Guide

PQQ is a small, brightly colored molecule that has become a fixture in mitochondrial supplements, usually mentioned in the same breath as CoQ10 and urolithin A. This guide explains what PQQ actually is, how it works, where it appears in the diet, what the safety picture looks like, and how it fits alongside urolithin A and the process of mitophagy.

What PQQ is

PQQ stands for pyrroloquinoline quinone, a small quinone compound first identified as a cofactor for certain bacterial enzymes. It is water-soluble, remarkably stable, and found in trace amounts throughout the natural world, from soil bacteria to human breast milk. In supplements it usually appears as a disodium salt, which is the form that has been assessed by food-safety regulators. Although PQQ is not classified as a vitamin, it behaves like a micronutrient: it turns up widely in the diet in very small amounts, and interest in it grew as researchers explored its redox chemistry and its effects on cellular signaling.

What makes PQQ chemically interesting is its durability as a redox agent. Many antioxidants are used up quickly once they neutralize a reactive molecule. PQQ can cycle through a large number of oxidation-reduction reactions before it is exhausted, which is one reason it attracted attention as a research compound. That redox activity is the foundation for how it is thought to support cells.

How PQQ works

PQQ is discussed in two main ways. The first is as a redox cofactor and antioxidant: because it can shuttle electrons repeatedly, it may help support the cell's handling of everyday oxidative stress. The second, and the reason it is marketed as a mitochondrial ingredient, involves cellular signaling that has been linked in laboratory studies to mitochondrial biogenesis, the process by which cells build new mitochondria.

Here it is important to be honest about where the evidence comes from. Much of the mitochondrial-biogenesis story for PQQ is built on cell-culture and animal research, where PQQ has been observed to influence signaling molecules such as PGC-1 alpha that regulate the creation of new mitochondria. Those are preclinical findings. Human data on PQQ exist and are growing, but they are smaller and more preliminary than the marketing language sometimes implies. In people, small studies have explored PQQ in relation to markers of oxidative stress and self-reported measures like fatigue and sleep quality, with mixed and early results. The responsible summary is that PQQ is a promising, well-studied-in-the-lab compound whose human evidence is still maturing. As a supplement it may support normal mitochondrial function and antioxidant balance; it is not a treatment for any disease.

What that means for claims

Because PQQ sits close to topics like energy, brain function, and metabolic health, it is easy to find overstated claims about it online. We keep to structure and function language: PQQ may help support cellular energy metabolism and the body's antioxidant defenses. If you are dealing with a specific concern involving fatigue, mood, memory, blood sugar, or heart health, that is a matter for your doctor, not something a supplement is meant to treat.

Dietary sources of PQQ

PQQ is genuinely dietary, though the amounts in food are tiny compared with supplement doses. Among the richer sources measured are fermented soybeans (natto), which stand out, along with parsley, green peppers, kiwi, papaya, spinach, and green tea. Cocoa and certain fermented foods also contribute. Because PQQ is water-soluble and widely distributed, most mixed diets supply a small, steady trickle of it, but reaching the amounts used in supplement research through food alone is not realistic. This gap between typical dietary intake and studied supplement doses is exactly why PQQ became a standalone supplement.

Safety and practical notes

PQQ disodium salt has been reviewed by food-safety authorities and is generally considered well tolerated at the modest doses used in supplements, which are typically in the low tens of milligrams per day rather than the gram-level doses seen with some other ingredients. Reported side effects are uncommon and tend to be mild, such as headache, drowsiness, or digestive upset, and some people notice these more at the higher end of the dosing range. As with any supplement, a few groups should be deliberate: anyone who is pregnant or nursing, anyone taking regular medication, and anyone with an existing health condition should talk with a clinician before starting. PQQ is not intended to diagnose, treat, or prevent any disease, and it is not a substitute for medical care. If you have a specific health concern, see your doctor.

How PQQ relates to urolithin A and mitophagy

PQQ and urolithin A are frequently grouped together as mitochondrial support ingredients, but they pull on different levers, and telling them apart helps you decide what you actually want.

PQQ is associated, mainly through preclinical research, with mitochondrial biogenesis, the building of new mitochondria, along with a role as a durable antioxidant. Urolithin A is associated with mitophagy, the recycling of old mitochondria. Mitophagy is the cell's quality-control process: it identifies mitochondria that are no longer working well, breaks them down, and clears the way for healthier ones. You can picture a well-run workshop needing two things: the ability to bring in new equipment and the discipline to retire broken machines. PQQ is talked about on the building side; urolithin A is talked about on the clearing side. For the full picture of that housekeeping process, see our explainers on what mitophagy is and mitochondrial health.

The evidence maturity also differs, and this matters. Urolithin A is a gut postbiotic made by the microbiome from ellagitannins in pomegranate, walnuts, and berries, and it now has several randomized human trials behind it, even if the field is still young. In humans, urolithin A has been shown to be safe and well tolerated up to 1,000 mg per day (Andreux et al. 2019, HUMAN), to shift a mitochondrial gene-expression signature, and to support muscle endurance and strength over roughly four months in separate randomized trials (Liu/D'Amico et al. 2022 and Singh et al. 2022, both HUMAN). A 2025 randomized trial reported support for immune-cell mitochondrial health in midlife adults (Nature Aging 2025, HUMAN), and a 2024 sports-nutrition trial looked at endurance and recovery markers in resistance-trained men. The foundational mitophagy and muscle findings originate in animal and cell work (Ryu et al. 2016, PRECLINICAL). A 2024 systematic review in Ageing Research Reviews describes the human evidence as still emerging, from short trials of modest size, which is a fair way to hold both PQQ and urolithin A: interesting, mechanistically reasonable, and not overstated.

If you want a direct comparison, see our urolithin A vs PQQ breakdown. New to urolithin A? Begin with the complete urolithin A guide, then browse the best urolithin A gummies to see how a clinically studied dose is delivered.

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This guide is educational and is not a substitute for advice from a qualified healthcare provider.