What it's actually good for
PQQ (pyrroloquinoline quinone) is a redox-active compound found in small amounts in foods like kiwi, parsley, and fermented soybeans. Its primary claim to fame is stimulating mitochondrial biogenesis — the creation of new mitochondria — via PGC-1alpha activation, which has obvious appeal for energy and aging. In cell and animal models, these effects are well-documented. The human evidence, however, consists of a handful of small pilot studies. One showed modest improvements in sleep quality and cognitive function in middle-aged and elderly Japanese adults, and another examined exercise performance with mixed results. These trials are too small and too few to draw confident conclusions. PQQ is not harmful at typical doses, but the evidence base is simply too thin to support the bold mitochondrial rejuvenation claims often made in marketing. It remains a compound in the early investigational stage for human benefit.