Researchers have found that non-menthol flavours attract people to use e-cigarettes and contributes to the higher use among youngsters.
The study published in the British Medical Journal Open, researchers reviewed 51 articles, including 17 published before 2016 and 34 published between 2016 and 2018.
"The use of e-cigarettes among youth may be a gateway to future cigarette use, and nicotine is especially harmful to developing adolescent brains," said the study's lead author Hannah Baker from the University of North Carolina.
"These facts, along with biomedical research linking vaping to multiple adverse health effects, make the recent precipitous increase in e-cigarette use among youth particularly alarming," Baker added.
The researchers found that five studies indicate that the non-menthol flavours in e-cigarettes decrease the perception that e-cigarettes are harmful, particularly fruit and candy flavours.
Six studies indicate that flavours increase the willingness of youth and young adults to try or initiate the use of e-cigarettes. Seven studies showed that the flavours increase product appeal among adults, the study said.
According to the researchers, the five studies revealed that flavours are a primary reason for adults to use e-cigarettes.
"Consistent evidence shows that flavours attract both youth and adults to use e-cigarettes," said the study's researcher Adam Goldstein.
"Given the fact that nicotine is highly addictive and can affect brain development - as well as these clear findings that the impact of flavours on youth is strong and consistent, we believe that banning non-menthol flavours in e-cigarettes will help reduce the epidemic of youth e-cigarette use," Goldstein said.
"Among youth, flavours increase not only preferences for e-cigarettes but they also increase e-cigarette product appeal, willingness to use, susceptibility to use and initiation, as well as decrease e-cigarette product harm perceptions," Goldstein added.