LONDON • A BBC investigation has found advertisements for major brands appearing alongside dozens of health-misinformation videos on YouTube.

Searching YouTube across 10 languages including English, Portuguese, Russian and Hindi, the BBC found more than 80 bogus health videos that included drinking baking soda or donkey's milk to cure cancer.

Some of these videos were accompanied by advertisements, some from well-known brands including Samsung, Heinz and Clinique. The companies have distanced themselves from the misleading content.

Samsung said its campaign had "no connection or correlation" with the fake cancer-cure video, while Kraft Heinz said it has taken steps to block the channel hosting one such video, according to the BBC.

Ten of the videos had more than a million views, despite being clinically unproven cures.

Earlier this year, Google-owned YouTube announced it would be "reducing recommendations of borderline content that could misinform in harmful ways".

But this change is gradual, and only affected a small number of English-language videos in the United States, leaving content in 10 other languages online and still able to generate revenue.

After BBC alerted YouTube, the latter then demonetised 70 videos, preventing video-makers from earning revenue from advertising.

The advertisements before many of these videos effectively monetise fake content, allowing Google and the video's poster to earn revenue from what could be dangerous misinformation, BBC said.

"Some of the things on YouTube and the Internet are really, positively dangerous, and it's unfiltered," said Professor Justin Stebbing, a leading cancer specialist at Imperial College, London.

YouTube's algorithm suggests similar videos, regardless of credibility, which can lead viewers down a rabbit-hole of dubious content.

Dr Chun-Hai Fung, an associate professor of epidemiology at Georgia Southern University, researched health information in English on YouTube, and found that the majority of the 100 most popular videos were uploaded by amateurs - not healthcare professionals.