Google’s AI Overviews feature cites YouTube more often than any medical website when answering health-related search queries, according to a German study that raises concerns about how reliable these summaries are for users.
Researchers at SE Ranking analysed responses to more than 50,000 health queries made in Germany and found that YouTube accounted for 4.43% of all sources cited by AI Overviews, making it the single most referenced domain. No hospital network, government health authority or academic medical institution came close. By comparison, Germany’s public broadcaster NDR ranked second, followed by established medical reference sites such as MSD Manuals and NetDoktor.
The researchers warned that YouTube is not a medical publisher and allows content from anyone, including non-experts, which raises risks when its videos are used to inform health advice. AI Overviews appeared in more than 82% of health searches analysed, suggesting the issue is widespread.
Google said the findings were limited to German-language searches and argued that AI Overviews surface high-quality content regardless of format, noting that many highly cited YouTube videos come from hospitals and licensed medical professionals. However, the researchers cautioned that these accounted for less than 1% of all YouTube links cited, meaning most references were to videos of unknown medical credibility.
Independent experts said the study suggests the risks of misleading health information in AI Overviews are structural, driven more by visibility and popularity than by medical authority.
