TikTok algorithms promote videos about self-harm and eating disorders among vulnerable teens, according to a study highlighting concerns about social media and its impact on youth mental health, AP reports.

Researchers at the nonprofit Center for Countering Digital Hate created TikTok accounts for fictional teens in the U.S., U.K., Canada and Australia. Researchers managing the accounts then liked videos about self-harm and eating disorders to see how the TikTok algorithm would react.

Within minutes, the hugely popular platform recommended videos about weight loss and self-harm, including photos of models and idealized body types, images of razor blades and discussions of suicide.

When the researchers created accounts with usernames indicating a particular vulnerability to eating disorders that included, for example, the words lose weight, the accounts contained even more dangerous content.

Social media algorithms work by identifying topics and content of interest to the user, who is then sent more of the same in order to maximize time on the site. But social media critics say the same algorithms that promote content about a particular sports team, hobby or dance hobby can send users down a rabbit hole of harmful content.

This is a particular problem for teens and children, who tend to spend more time online and are more vulnerable to bullying, peer pressure or negative content about eating disorders or suicide, said Josh Golin, executive director of Fairplay.

He added that TikTok is not the only platform that fails to protect young users from malicious content and aggressive data collection.