TL;DR
Google’s AI Overviews cites YouTube more than any medical website when answering health queries, according to research analysing over 50,000 searches. YouTube accounted for 4.43% of all citations—no hospital, government health portal, or medical institution came close.
Popularity Over Authority
The study by SE Ranking found AI Overviews appeared on more than 82% of health searches analysed. When researchers examined the 465,823 total citations, YouTube dominated with 20,621 references. The next closest was NDR.de, a German public broadcaster, with 14,158 citations.
“This matters because YouTube is not a medical publisher,” the researchers wrote. “It is a general-purpose video platform. Anyone can upload content there—board-certified physicians, hospital channels, but also wellness influencers, life coaches, and creators with no medical training at all.”
Google countered that its AI Overviews surfaces “high-quality content from reputable sources, regardless of format” and that the study’s German-language focus limits broader conclusions. The company pointed out that 96% of the 25 most-cited YouTube videos came from medical channels.
A Tiny Slice of Reassurance
However, the researchers noted those 25 videos represent less than 1% of all YouTube links cited by AI Overviews on health topics. “With the rest of the videos, the situation could be very different.”
This follows a Guardian investigation that found people being put at risk by false health information in AI Overviews responses, including “dangerous” misinformation about liver function tests.
Hannah van Kolfschooten, an AI and health law researcher at the University of Basel, said the findings show “risks posed by AI Overviews for health are structural, not anecdotal.”
Looking Forward
With AI Overviews reaching 2 billion people monthly, the question of source quality in health responses has significant public health implications. The research suggests visibility and popularity may be driving health knowledge in AI search results rather than medical reliability.