Dietary sources of PQQ include various foods, particularly those with a strong antioxidant profile. Fermented foods, green peppers, kiwi, spinach, and tofu are known to contain measurable amounts of PQQ. However, the levels found in food are typically lower compared to what one might achieve through supplementation. As a result, PQQ supplements have surged in popularity, with users seeking to harness its potential health benefits, particularly for enhancing energy levels, cognitive performance, and overall vitality.