Google’s AI Overviews cite YouTube more often than any medical website when answering health-related search queries, according to a new study that raises concerns about the reliability of information seen by around 2 billion users each month.
Researchers at SE Ranking analysed more than 50,000 health queries made in Germany and found that YouTube accounted for 4.43% of all citations used in AI Overviews, making it the single most referenced source. No hospital network, government health authority or academic medical institution came close to that level of citation.
The researchers warned that YouTube is not a medical publisher and hosts content from a wide range of creators, including people with no medical training. While some videos come from hospitals or licensed professionals, the study found these made up less than 1% of all YouTube links cited in health-related AI Overviews.
The study also showed that AI Overviews appeared in more than 82% of health searches analysed. The next most cited sources after YouTube were Germany’s public broadcaster NDR, followed by established medical reference and consumer health sites.
Google said its AI summaries are designed to surface high-quality information from reputable sources in different formats and argued that many cited YouTube videos are produced by medical professionals. However, independent experts said the findings suggest the system prioritises popularity and visibility over medical authority, posing structural risks when used for health information.
