PQQ is a redox cofactor that is naturally found in various foods, such as kiwifruit, fermented soybeans, green peppers, and spinach. It has been researched for its potential to improve mitochondrial function, which is vital for energy production in our cells. Mitochondria are often referred to as the powerhouses of the cell, converting nutrients into energy. With age, mitochondrial function can decline, leading to fatigue and various health issues. This is where PQQ comes into play.