(WBIR- Knoxville) Current evidence suggests the potential benefits of electronic cigarettes outweigh the harm, according to a new review published by the Addiction Journal.

The e-cigarette trend has grown substantially in the Knoxville area over the last year, said Glenn Cate, owner of Vintage Vapors. He opened his store in September last year and said now there are more than 20 e-cigarette shops.

"It shows that this isn't just a fad," Cate said. "It is something that legitimately helps people."

Cate said he started smoking when he was 15 and continued smoking for more than 30 years. E-cigarettes were the only thing that helped him quit, he said, and he hasn't picked up a conventional cigarette in almost four years.

Martha Buchanan, director of the Knox County Health Department, said she would still like to see more research to determine if there are any benefits.

"All we see is anecdotal evidence," she said, "so people saying that they've had benefits from e-cigarettes."

Buchanan said e-cigarettes are not an approved nicotine replacement therapy. She said FDA-approved nicotine replacement therapies include nicotine gums, lozenges, and patches.

Cate said the four standard ingredients in e-cigarettes are propylene glycol, vegetable glycerin, flavoring, and nicotine. These ingredients are in other FDA-approved products, he said, but have not been approved as e-liquid for e-cigarettes. Tobacco is not an ingredient in e-cigarettes, which separates it from conventional cigarettes, he said.

The review mentioned e-cigarettes could provide a gateway to smoking, which was listed as a potential harm.

"The earlier folks start using something addictive, the more likely they are to continue using it and then move onto other things later in life," Buchanan said. "We've seen that with cigarettes and may see that with e-cigarettes as well."

Cate said even though there aren't any long-term studies yet, he has seen his health improve "tremendously" since switching to the e-cigarettes.

"You can't say it's going to help them to quit smoking," Cate said. "But it's making us switch to something that's healthier."