Google’s AI Overviews cite YouTube more often than any medical website when answering health-related search queries, according to a new German study that raises concerns about the reliability of information seen by billions of users.
Researchers analysed more than 50,000 health searches in Germany and found that AI Overviews appeared in over 80% of results. The most frequently cited source was YouTube, accounting for 4.43% of all citations—more than hospitals, government health portals or academic institutions. YouTube is owned by Google.
While Google says its AI summaries draw on reputable sources such as the Centers for Disease Control and Prevention and the Mayo Clinic, researchers warned that YouTube is not a medical publisher and hosts content from both qualified professionals and untrained influencers.
Experts said the findings suggest a structural risk in how AI Overviews are designed, potentially prioritising popularity and visibility over medical authority. Google responded that many cited YouTube videos come from hospitals and licensed medical creators, but researchers noted these represent only a small fraction of all YouTube links used.
The study adds to growing scrutiny of AI-generated health information after previous investigations found inaccurate and potentially harmful medical advice appearing in AI Overviews.
