There is No Caffeine in Damiana-Dismantling Filter Bubbles and Echo Chambers in Scientific Referencing

The scientific literature is increasingly challenged by miscitation, publication bias, and the uncritical perpetuation of false information. One such case concerns the purported presence of caffeine in damiana, a botanical ingredient marketed for "sexual well-being". While consumer perception and regulatory implications make caffeine content highly relevant, a systematic review of the literature indicates that claims of caffeine in damiana (Turnera diffusa) largely stem from erroneous or circular referencing, including citations of studies where caffeine was never reported. To address this discrepancy experimentally, we conducted NMR analyses on authenticated aerial and seed material of T. diffusa and seeds of T. ulmifolia. No caffeine was detected, with a detection limit of < 4 nM, corresponding to < 4 µg caffeine per daily serving of damiana. These findings confirm that damiana is effectively caffeine-free. Beyond correcting a specific phytochemical misconception, this study highlights how flawed referencing practices can perpetuate modern "scientific myths", emphasizing the need for more rigorous citation ethics and the value of experimental data. Addressing such errors is critical not only for scientific accuracy but also for consumer trust and evidence-based regulatory decision-making.