Google’s AI Overviews Are Citing YouTube More Than Medical Authorities

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Google’s AI-powered search feature, AI Overviews, is increasingly shaping how people access health information. But new research suggests a troubling trend: when answering health-related questions, Google’s AI is citing YouTube more often than any medical website.

AI Overviews appear at the top of Google search results and are viewed by around 2 billion users every month. Google has repeatedly stated that these summaries rely on “reliable” sources such as the CDC, Mayo Clinic, and other reputable health institutions.

However, a recent study challenges that claim.

What the Study Found

Researchers at SE Ranking, an SEO analytics firm, analyzed 50,807 health-related search queries conducted in Germany using Google’s AI Overviews.

Their findings were striking:

• YouTube was the single most cited source

• 20,621 citations out of 465,823 total citations

• This means YouTube accounted for 4.43% of all AI Overview sources

• No hospital network, government health authority, or academic institution came close

The next most cited sources were:

• German public broadcaster: 3.04%

• medical reference: 2.08%

• consumer health portal: 1.61%

• doctor career platform: 1.53%

Why This Matters

YouTube is not a medical publisher.

While it hosts content from hospitals, doctors, and universities, it also allows:

• Wellness influencers

• Life coaches

• Unlicensed creators

• Misinformation-driven channels

As the researchers wrote:

When AI systems rely heavily on such platforms, medical reliability can be outweighed by visibility and popularity.

A Structural Risk, Not an Isolated Bug

The study was conducted in Germany, a country with one of the most strictly regulated healthcare systems in the world. The researchers argue this makes the findings even more concerning.

If AI systems rely heavily on non-medical sources even in tightly regulated environments, the issue may be global — not regional.

AI Overviews appeared in over 82% of health-related searches, meaning most users are being exposed to AI-generated medical summaries by default.

Google’s Response

Google told The Guardian that:

• AI Overviews are designed to surface high-quality content “regardless of format”

• Many YouTube videos cited come from licensed medical professionals

• 96% of the top 25 cited YouTube videos were from medical channels

However, researchers pointed out a key caveat:

Those 25 videos represent less than 1% of all YouTube links cited by AI Overviews.

What remains unknown is the quality and credibility of the remaining 99%.

Real-World Consequences

This research follows earlier investigations showing dangerous inaccuracies in Google’s AI health summaries.

In one case, AI Overviews provided incorrect information about liver function tests, potentially leading people with serious liver disease to believe they were healthy. Google later removed AI Overviews for some medical searches — but not all.

The Bigger Question

Hannah van Kolfschooten, a researcher in AI, health, and law at the University of Basel, summarized the concern clearly:

As AI increasingly mediates access to health knowledge, the core issue isn’t whether YouTube can host expert content — it’s whether algorithmic popularity should ever outweigh medical authority.

For tools that billions rely on, that distinction could be a matter of public health.