Introduction to Google’s AI Overviews
Google’s AI Overviews may be relying more on YouTube than official medical sources when answering health questions, according to new research from SEO platform SE Ranking. The study analyzed 50,807 German-language health prompts and keywords, captured in a one-time snapshot from December using searches run from Berlin.
What the Study Measured
The analysis focused on which sources Google’s AI Overviews cite for health-related queries. In the dataset, AI Overviews appeared on more than 82% of health searches, making health one of the categories where users are most likely to see a generated summary instead of a list of links. The report also cites consumer survey findings suggesting people increasingly treat AI answers as a substitute for traditional search, including in health.
YouTube as a Primary Source
Across SE Ranking’s dataset, YouTube accounted for 4.43% of all AI Overview citations, or 20,621 citations out of 465,823. The next most cited domains were ndr.de (14,158 citations, 3.04%) and MSD Manuals (9,711 citations, 2.08%). The authors argue that the ranking matters because YouTube is a general-purpose platform with a mixed pool of creators, including licensed clinicians, hospitals, and creators without medical training.
Reliability of Sources
SE Ranking categorized citations into "more reliable" and "less reliable" groups based on the type of organization behind each source. It reports that 34.45% of citations came from the more reliable group, while 65.55% came from sources "not designed to ensure medical accuracy or evidence-based standards." Academic research and medical journals accounted for 0.48% of citations, German government health institutions accounted for 0.39%, and international government institutions accounted for 0.35%.
Comparison with Organic Search
The report compared AI Overview citations to organic rankings for the same prompts. While SE Ranking found that 9 out of 10 domains overlapped between AI citations and frequent organic results, it says the specific URLs frequently diverged. Only 36% of AI-cited links appeared in Google’s top 10 organic results, 54% appeared in the top 20, and 74% appeared somewhere in the top 100.
Connection to Previous Reporting
The SE Ranking report explicitly frames its work as broader than spot-checking individual responses. "The Guardian investigation focused on specific examples of misleading advice. Our research shows a bigger problem," the authors wrote, arguing that AI health answers in their dataset relied heavily on YouTube and other sites that may not be evidence-based. Following The Guardian’s reporting, Google removed AI Overviews for certain medical queries.
Why This Matters
This report adds a concrete data point to a problem that’s been easier to talk about in the abstract. The source mix raises questions about what Google’s systems treat as "good enough" evidence for health summaries at scale. In this dataset, government and academic sources barely showed up compared to media platforms and a broad set of less reliability-focused sites. That’s relevant beyond SEO, as the failure modes can be high-stakes, and Google’s pullback on some medical queries suggests the company is willing to disable certain summaries when scrutiny gets intense.
Looking Ahead
SE Ranking’s findings are limited to German-language queries in Germany and reflect a one-time snapshot, which the authors acknowledge may vary over time, by region, and by query phrasing. Even with that caveat, the combination of this source analysis and the recent Guardian investigation puts more focus on two open questions: how Google weights authority versus platform-level prominence in health citations, and how quickly it can reduce exposure when specific medical query patterns draw criticism.
Conclusion
The reliance of Google’s AI Overviews on YouTube and other less reliable sources for health information is a concern. As people increasingly trust AI for health advice, it’s crucial for Google to ensure the accuracy and reliability of its health summaries. The company must weigh the importance of authority and evidence-based sources in its AI Overviews, and be willing to disable certain summaries when they are found to be misleading or inaccurate. By doing so, Google can provide users with trustworthy health information and maintain the integrity of its search results.