Google’s AI Overviews feature most often cites YouTube when answering health-related search queries, according to a new study that raises concerns about the reliability of information seen by billions of users each month.
Researchers analysed more than 50,000 health searches made in Germany and found YouTube accounted for 4.43% of all citations in AI-generated summaries—more than any hospital network, government health portal or medical institution. The next most cited sources were German public broadcaster NDR and the medical reference site MSD Manuals.
The authors warned that YouTube is not a medical publisher and hosts content from understanding influencers as well as qualified professionals, meaning users may struggle to judge credibility. While Google said AI Overviews surface high-quality information regardless of format and often cite expert-run YouTube channels, researchers stressed that the most credible videos represented less than 1% of all YouTube links used.
Independent experts said the findings suggest risks in how AI Overviews are designed, with popularity and visibility appearing to outweigh medical authority—particularly worrying for a tool that now appears in more than 80% of health-related searches.
