Despite their advertisements, electronic cigarettes are not an effective means to quit smoking, according to an online study by the National Cancer Center.

“Some e-cigarette products are touted as being useful for smoking cessation, but we do not recommend that they be used for that purpose,” an official at the center said.

The survey covered 798 people ranging in age from 20 to 69 who said they attempted to quit smoking over the last five years.

The respondents were asked which method they chose to stop smoking and whether their attempts succeeded.

The success rate for people who used e-cigarettes was 40 percent lower than the rate for people who did not use the products, the study found.

People who received drug therapy at hospitals were more likely to quit smoking than those who did not see physicians, the study showed.

E-cigarettes heat liquid containing nicotine, aromatics and other chemicals so users can inhale the generated vapor.

Although producing and selling nicotine are restricted by law, individuals can import liquid containing nicotine by themselves.

The health ministry’s white paper on tobacco also pointed out that some e-cigarette products contain carcinogens that “could negatively affect the health” of users.

“E-cigarettes could help smokers kick the habit,” said Itsuro Yoshimi, a senior official of the center. “But they could also have a negative impact: deceiving smokers so they will not select more effective smoking cessation means.”