SAN FRANCISCO — Whether it is a video claiming the earth is flat or the moon landing was faked, conspiracy theories are not hard to find on Google’s YouTube. But in a significant policy change, YouTube said on Friday that it planned to stop recommending them.

After years of criticism that YouTube leads viewers to videos that spread misinformation, the company said it was changing what videos it recommended to users. In a blog post, YouTube said it would no longer suggest videos with “borderline content” or those that “misinform users in a harmful way” even if the footage did not violate its community guidelines.

YouTube said the number of videos affected by the policy change amounted to fewer than 1 percent of all videos on the platform. But given the billions of videos in YouTube’s library, it is still a large number.

YouTube and other powerful technology platforms have faced rising criticism for failing to police the content that users post.