Google's AI Health Tool Cites YouTube More Than Medical Authorities
Google's AI Overviews feature, which provides generative AI summaries at the top of search results, cites YouTube more frequently than any established medical website when answering health-related queries, according to a comprehensive new study. This finding raises significant questions about the reliability of a tool viewed by approximately 2 billion people every single month.
YouTube Dominates Citations in Health Query Responses
Researchers from the search engine optimisation platform SE Ranking conducted an in-depth analysis of responses to over 50,000 health-related prompts and keywords. The study, which captured Google searches originating from Berlin, discovered that the video-sharing platform YouTube constituted a substantial 4.43% of all citations within AI Overviews for health topics. This percentage far exceeded citations from any hospital network, government health portal, medical association, or academic institution.
The single most cited domain was YouTube, with 20,621 citations out of a total of 465,823 analysed. In comparison, the next most cited source was the German public broadcaster NDR.de, with 14,158 citations (3.04%), followed by the medical reference site Msdmanuals.com with 9,711 citations (2.08%). Germany's largest consumer health portal, Netdoktor.de, and a career platform for doctors, Praktischarzt.de, rounded out the top five.
Concerns Over Source Authority and Public Health Risk
The researchers emphasised a critical concern: YouTube is not a medical publisher. It is a general-purpose video platform where content can be uploaded by anyone, including board-certified physicians and hospital channels, but also wellness influencers, life coaches, and creators with no formal medical training whatsoever. This lack of inherent vetting for medical authority poses a potential risk to public health.
"This matters because YouTube is not a medical publisher," the study authors stated. The reliance on a platform where medical expertise is not guaranteed suggests that visibility and popularity may be driving citation choices more than medical reliability.
Google's Response and Study Limitations
In response to the findings, Google stated that AI Overviews is designed to surface high-quality content from reputable sources, regardless of format. The company highlighted that a variety of credible health authorities and licensed medical professionals create content on YouTube. Google also pointed out that the study's findings, based on German-language queries in Germany, should not be extrapolated to other regions.
Furthermore, Google noted that of the 25 most cited YouTube videos in the study, 96% were from medical channels, with 21 clearly noting content from licensed or trusted sources. However, the researchers cautioned that these 25 videos represent less than 1% of all the YouTube links cited by AI Overviews on health, meaning the situation for the vast majority of cited videos could be markedly different.
Structural Risks and Expert Commentary
The research adds to growing scrutiny of AI Overviews, following a Guardian investigation that found people were being put at risk by false and misleading health information in the tool's responses. Experts have described some outputs as "dangerous" and "alarming."
Hannah van Kolfschooten, a researcher specialising in AI, health and law at the University of Basel, commented on the new study's implications. "This study provides empirical evidence that the risks posed by AI Overviews for health are structural, not anecdotal," she said. "It becomes difficult for Google to argue that misleading or harmful health outputs are rare cases. Instead, the findings show that these risks are embedded in the way AI Overviews are designed."
Methodology and Broader Implications
The SE Ranking study was conducted as a snapshot in December 2025, using German-language queries reflective of typical user searches in Germany. The researchers chose Germany specifically because its healthcare system is strictly regulated by a mix of German and EU directives, standards, and safety regulations.
They argued that if AI systems rely heavily on non-medical or non-authoritative sources even in such a tightly regulated environment, the issue likely extends beyond any single country. The study found that AI Overviews surfaced on more than 82% of health searches analysed.
While the researchers acknowledged limitations—such as the study being a single snapshot whose results could vary by time, region, and query phrasing—they maintained that the core findings are cause for alarm. The heavy weighting towards YouTube citations underscores a potential systemic flaw in how AI Overviews sources and prioritises health information for its vast global audience.
