pqq

Pyrroloquinoline quinone (PQQ) is a redox-active quinone that serves as a cofactor for certain bacterial dehydrogenases. Discovered in bacteria in the 1970s, PQQ is not considered an essential nutrient for humans, though it is studied for potential biological effects.

Chemically, PQQ is a bicyclic quinone that participates in one-electron transfer reactions during oxidation-reduction processes. In bacteria it functions as a cofactor for enzymes such as glucose dehydrogenase, supporting energy metabolism. Its role as a human nutrient remains unconfirmed by regulatory authorities.

Dietary sources of PQQ include a variety of foods, particularly some fermented products and plant-derived foods. It also occurs at trace levels in fruits, vegetables, and dairy. The amounts in the diet are typically small and intake varies with food choice and preparation.

In research, PQQ has been investigated for effects on mitochondrial biogenesis, antioxidant defense, and neuroprotection in cell culture and animal studies. Human data are limited and inconclusive, and there is no proven medical use or official recommended intake.

PQQ is marketed as a dietary supplement in some jurisdictions. Regulatory status differs by country, and there is no established dietary requirement or universal upper limit. Typical supplement doses range from about 10 to 20 mg per day, but long-term safety in humans remains inadequately characterized.