Major e-cigarette makers were contrite about youth vaping in meetings with Food and Drug Administration Commissioner Scott Gottlieb, Gottlieb said Wednesday, with some companies in favor of moving the minimum age to buy tobacco from 18 to 21.

The five major e-cigarette companies met with Gottlieb separately in recent weeks as they face a massive crackdown from the FDA on minors using their products. Gottlieb has hinted about possibly banning sales of e-cigarettes in convenience stores to help stem the skyrocketing use of e-cigarettes among adolescents.

“The companies acknowledged the serious public health consequences associated with youth use of tobacco products,” Gottlieb said in a statement Wednesday.

Gottlieb did not divulge which companies wanted to increase the minimum buying age. Such a move could require an act of Congress.

E-cigarette use has increased among middle and high-school students. About 3 of every 100 middle school students reported using an e-cigarette in 2017 in the past 30 days, an increase from 0.6 percent in 2011. For high school students, nearly 12 out of every 100 students reported use in 2017, an increase of 1.5 percent from 2011, according to Centers for Disease Control and Prevention data.

JUUL Labs, Altria Group (formerly Philip Morris), Reynolds American, Fontem Ventures, and Japan Tobacco participated in the meetings with FDA leadership over a series of meetings over the past few weeks.

The companies represent more than 97 percent of the market for closed-system e-cigarettes, which are the most popular type of e-cigarettes. The product cannot be modified by the user and are sold as a single unit. An open-system e-cigarette can be customized and the components can be changed.

Gottlieb said in a statement that the five companies acknowledged the role that flavored e-cigarette products “play in appealing to kids, as well as the role that flavored e-cigarettes can also play in helping adult smokers quit.”

The FDA has called for 17 makers of e-cigarette flavored liquids to pull kid-friendly flavors that resemble cookies or candy. The liquids are turned into a vapor by the e-cigarette and then inhaled by the user.

The companies gave the FDA several different proposals to deal with this issue. One such proposal would pull certain products that are more appealing to kids off the market until the FDA approves them.

Currently e-cigarettes on the market have to get agency approval by 2022 to stay on the shelves, but Gottlieb has toyed with changing that deadline.

Gottlieb said that the comments would inform the FDA’s next move on e-cigarettes.

“We still believe that new innovations that don’t use combustion, such as many e-cigarettes, may offer an important opportunity for adults to transition off combustible tobacco,” he said. “But, as I’ve said before, the current trends in youth use are not tolerable.”