(Reuters) - E-cigarette maker Juul Labs Inc will immediately stop selling its mint-flavored nicotine cartridges in the United States, the company said on Thursday, after new signs that the mint variety is increasingly popular among teenagers.

FILE PHOTO: Juul brand vape cartridges are pictured for sale at a shop in Atlanta, Georgia, U.S., September 26, 2019. Picture taken September 26, 2019. To match Special Report JUUL-ECIGARETTE/ REUTERS/Elijah Nouvelage/File Photo

Research released this week in the Journal of the American Medical Association found that mint was by far the most popular flavor among U.S. 10th and 12th grade Juul users, with more than 40% saying it was the most frequently used variety of nicotine pod.

One of the studies also showed Juul e-cigarettes were by far the most popular of any brand used by high school and middle school students, with nearly 60% of high schoolers and 54% of middle schoolers saying Juul was their usual brand.

Juul Chief Executive K.C. Crosthwaite called the results of those studies “unacceptable” in announcing the move.

“We must reset the vapor category in the U.S. and earn the trust of society by working cooperatively with regulators, Attorneys General, public health officials, and other stakeholders to combat underage use,” said Crosthwaite, who took the helm in September after serving as a top executive at Marlboro maker Altria Group Inc, which has a 35% stake in Juul.

Over the last year Juul has scaled back the number of flavors it offers to stave off mounting pressure from regulators over the surging popularity of its products with teenagers.

The company said last year it would pull popular flavors such as mango, cucumber and fruit from retail store shelves in the United States, leaving only tobacco, mint and menthol flavors in traditional retail outlets but still selling others online.

Last month Juul announced it would also stop selling fruit- and dessert-flavored nicotine pods online in the United States.

The studies released this week suggest those efforts have not reduced Juul’s popularity among teenagers.

The percentage of high schoolers using e-cigarettes increased to 27.5% this year, up from 20.8% last year. Moreover, data from one of the new studies suggest that mint and menthol flavors have taken the place of fruit- and candy-flavored nicotine liquids this year, after Juul restricted retail sales of flavors except mint, menthol and tobacco last fall.

Use of mint or menthol flavors increased among high school e-cigarette users between 2018 and 2019, growing from 38.1% to 57.3% this year, according to the analysis. Use of “fruit” or “candy, dessert or other sweets,” on the other hand, declined this year.

Juul said on Thursday it will stop selling mint nicotine pods online in the United States immediately, and stop accepting new orders for mint cartridges from retailers. Juul still sells mint and other sweet flavors in international markets.

The move comes as the Trump administration is considering a ban on all e-cigarette flavors except tobacco. President Donald Trump and Health and Human Services Secretary Alex Azar announced the plan in September and said a final decision would be made “in the coming weeks.”

No final decision has been announced. After that announcement, Juul CEO Kevin Burns stepped down and was replaced by Crosthwaite, who said the company would refrain from lobbying the administration on the proposed flavor ban.

Meredith Berkman, co-founder of Parents Against Vaping E-cigarettes, said on Thursday that Juul’s move was “too little, too late,” adding that she expects teenagers will simply flock to menthol-flavored e-cigarettes if mint is removed from sale.

“If you really cared, you would include menthol,” she said. “That’s where the kids will go. Everyone knows it.”