Google’s AI Overviews feature most frequently cites YouTube when answering health-related search queries, according to new research that raises concerns about the reliability of information seen by up to 2 billion users each month.
The study, conducted by researchers at SE Ranking, analysed more than 50,000 German-language health searches made in Berlin. It found that YouTube accounted for 4.43% of all citations used in AI Overviews—more than any hospital network, government health body or academic institution. By comparison, established medical sources such as Centers for Disease Control and Prevention and Mayo Clinic appeared less frequently.
Researchers warned that YouTube is not a medical publisher and hosts content from a wide range of creators, including non-experts, meaning visibility and popularity may outweigh medical authority. AI Overviews appeared in more than 82% of the health searches analysed.
Google said the findings were limited to Germany and that AI Overviews are designed to surface high-quality information from reputable sources across formats, noting that many highly cited YouTube videos come from hospitals and licensed professionals. However, researchers cautioned that those videos represented less than 1% of all YouTube links cited.
Independent experts said the results suggest risks are built into the design of AI Overviews, potentially prioritising engagement over medical reliability.
