One of the great unanswered questions for smokers who are trying to quit — and for the advocacy groups trying to help them — is whether electronic cigarettes are friends or foes.

University of Minnesota researchers aim to address that dilemma with a study examining exactly what smokers inhale when they breathe e-cigarette vapors and how “vaping” affects the body. Researchers will collect blood, urine and saliva samples from at least 25 smokers who use only e-cigarettes and at least 25 who use them with traditional cigarettes.

“The first step is to say, ‘Well, how toxic are these products? What is actually in them?’ ” said Dorothy Hatsukami, associate director for cancer prevention and control in the U’s Masonic Cancer Center.

E-cigarettes, rechargeable devices that heat liquid nicotine or other flavored substances into a vapor that the user inhales, have been marketed as a safer alternative to tobacco. Yet a lack of regulation on their manufacture and contents makes it hard to know if they’re safer than traditional cigarettes and whether they can be used to safely help wean people off tobacco, Hatsukami said.

“It’s like a Wild West out there,” she said.

Some e-cigarettes that are promoted as nicotine-free, for example, have been found to contain the addictive substance, while others contain little or no nicotine despite claims to the contrary.

Some previous studies have chemically analyzed the contents of e-cigarettes. The Minnesota study aims to go a step further by examining how the contents of different kinds of e-cigarettes affect the body.

The market for e-cigarettes has grown rapidly — sales have doubled annually since 2008 and are expected to reach $1.6 billion this year. About 6 percent of adults have tried them, and the share of high school students who have tried them hit 10 percent last year, according to the U.S. Centers for Disease Control and Prevention.

Heidi Scholtz, 20, a German and theater student at Hamline University, tried her first one two years ago because she was tired of going outside in the snow and cold to smoke. Before long, she said, she was using only e-cigarettes and was surprised at what happened when the weather warmed up and she tried a cigarette.

“It tasted disgusting,” she said.

Now Scholtz uses only e-cigarettes, and has kicked a cigarette habit that started when she was 15. A close friend tried them at her urging, but now uses both.

Help smokers quit?

Studies nationally have produced mixed results about whether e-cigarettes help people quit or reduce smoking — or simply supplement real tobacco. Clearway Minnesota, a nonprofit quit-smoking group, has taken a noncommittal stance on them.

Spokesman Mike Sheldon said it’s great if they help some people quit. But, he added, the lack of science about their contents makes it hard to endorse them over proven stop-smoking strategies of counseling combined with such well-studied supplements as nicotine patches or gum.

The recent increase in youth use of e-cigarettes also is troubling, Sheldon said. “We just don’t know enough about these,” he said.

The Minnesota Clean Indoor Air Act does not apply to e-cigarettes, which can be smoked indoors unless banned by local laws or individual establishments. The city of Duluth banned them from public indoor locations because so little is known about their effect on people who inhale the vapors secondarily.

Clearway would support extending the state ban to e-cigarettes, Sheldon said. However, a group of former cigarette smokers have formed the Minnesota Vapers Advocacy Group to fight the idea.

The group’s president, Matt Black, said his first e-cigarette meant his last real cigarette. A device that physically mimicked his smoking mannerisms was key to to quitting.

“For 17 years, I was constantly hand to mouth (with a cigarette),” Black said. “I was blowing out smoke. I was breathing differently. All of those things play a role in that addiction. We found a way to maintain those habits in a way that’s not going to kill us.”

Black said he hopes the U study will ultimately find e-cigarettes safe, so more people would use them to quit real cigarettes.

Hatsukami said a key aspect of the study is looking at the different types of e-cigarettes to see if some are more harmful than others. (To enroll, call 612-624-4568.)

“Although the majority of the products don’t contain toxicants that are cancer-causing, there are a few that do,” she said. “There is a lot of variability out there.”