Research into Google’s AI Overviews has uncovered a seriously troubling pattern: The feature cites YouTube more often than it cites hospital networks, medical associations, or government health portals when answering health questions. German researchers analyzing over 50,000 health queries in December 2025 found that YouTube accounted for 4.43% of all AI Overview citations, nearly tripling the number from leading medical reference sites, The Guardian reports.
For the duration of the study, only 34.45% of Google’s AI Overview citations came from reliable, science-based medical sources such as hospitals and clinics. The remaining 65.55% originated from sources that do not ensure medical accuracy or follow evidence-based standards. Academic journals and government health institutions together accounted for roughly 1% of citations.
YouTube ranks 11th in traditional Google search results for health queries, but jumps to first place in AI Overview citations. All this comes after Google pulled its AI Overviews from several health-related search queries earlier this month, following an investigation that found the summaries provided misleading and potentially harmful medical advice.
Across all query topics, AI Overviews reach 2 billion monthly users globally. Hannah van Kolfschooten, a researcher at the University of Basel who specializes in AI and health law and was not involved in the study, calls the risks “structural, not anecdotal,” meaning they are built into how AI Overviews are created. She also says that YouTube’s popularity shows that “visibility and popularity, rather than medical reliability,” determines what information the system chooses.
