Denver (CNN) Ed Rothbauer broke his back years ago and was paralyzed from the ribs down. Today, he walks with a cane. It's a recovery he attributes, in part, to what he believes is a healing tea called kombucha.

"I started doing it at home. And I think it was about 30 days to about two months I started getting movement in my legs," Rothbauer said.

Rothbauer said he can't credit kombucha alone for his healing but said it marked a turning point in his recovery.

"It did make me feel really good, and I think the probiotics helped me assimilate nutrients and helped me heal," he said.

Yet federal regulators now warn the fermented concoction may not be all good, and say the drink, that's currently sold on grocery store shelves, available to anyone, might need to be moved to a liquor store.

Some warn that even with low levels of alcohol there are risks to pregnant women and children, or those who are allergic.

What is kombucha?

Kombucha isn't sold as an alcoholic beverage. It's marketed as a health drink, a fermented tea with a signature vinegary flavor and a key ingredient in the production that looks like a mysterious giant mushroom.

The so-called mushroom is a combination of yeast and bacteria.

"That's why they call it the Manchurian mushroom, but there is no fungal property to it at all," said Rothbauer, who now owns High Country Kombucha, which is nestled in the Rocky Mountains in Colorado.

Rothbauer said the so-called mushroom is actually a combination of yeast and bacteria that creates a powerful probiotic meant to boost immunity and offer other medicinal healing benefits.

The drink has been around for thousands of years and is believed to have originated in Asia. It's been popular with health food enthusiasts for years. But it's recently become mainstream, with an estimated $600 million in sales this past year, according to an industry advocacy group. You can find it in grocery store chains such as Safeway and Kroger.

Rothbauer's High Country Kombucha factory produces 10,000 cases of kombucha a month, 8,000 bottles per day, in 13 flavors. It ship the bottles to stores all over the United States. Rothbauer said he hopes to quadruple his business in four years if the feds don't stop its growth.

Quandary over alcohol content

The Alcohol and Tobacco Tax and Trade Bureau recently sent letters to kombucha producers, including Rothbauer, saying some samples tested above the .5% alcohol-by-volume threshold for nonalcoholic beverages. That's about one-eighth the alcohol content of a light beer.

Rothbauer admits alcohol can be a result of the fermentation process when the tea, sugar, bacteria and yeast combine. While they test every batch of kombucha that's bottled and boxed at High Country Kombucha before shipping, he said the alcohol content can increase if the beverage isn't refrigerated.

But could someone get drunk off kombucha?

"No, no," Rothbauer said, laughing. "I don't know if you've tasted kombucha, but it's not something that you drink bottle after bottle. You know, this is something that's fermented. It would be like trying to drink vinegar bottle after bottle. And you would have to drink eight bottles (of kombucha) just to get the buzz of one beer."

Kombucha tea has gone mainstream and is available in grocery store chains.

But the Alcohol and Tobacco Tax and Trade Bureau has threatened businesses found in violation with a fine of up to $11,000. Its letter tells producers they must figure out a way to keep the alcohol level under 0.5% consistently or change the labeling to mark it as an alcoholic beverage. In many states, doing so would mean paying more taxes and ending sales in grocery stores.

"It kills the industry. People that are looking for healthy alternatives don't go to liquor stores to look for it," Rothbauer said.

Congressman takes up cause

U.S. Rep. Jared Polis, a Colorado Democrat, called it a "complete misclassification" to label kombucha as alcohol. Polis, a kombucha drinker himself, is now going to bat for kombucha producers in his home state.

"I've enjoyed it, many enjoy it, and it has nothing to do with an alcoholic beverage." Polis said.

He has asked federal regulators for leniency. Polis said he believes reliable testing is the real issue. He's working with kombucha brewers to advocate for updated testing methods.

When contacted by CNN, Thomas Hogue, a spokesman at the Alcohol and Tobacco Tax and Trade Bureau, said the agency has agreed to look into alternative testing.

What about the health claims?

While the future of kombucha hangs in the balance, health experts said scrutiny is warranted and consumers should be cautious.

"I think that some of the risks (around the alcohol content) outweigh some of the benefits around kombucha -- at least some of the potential benefits, nutrient benefits," warned Bonnie Jortberg, a nutritionist with the University of Colorado School of Medicine.

To play it safe, Jortberg said some of the potential health benefits of kombucha, such as probiotics and antioxidants, can be found in other products -- yogurt, fruits, vegetables and even simple green tea -- but without the risk of unpredictable alcohol content.

She said she pushes for as much transparency in labeling as possible, because "as a consumer, that's how we can make an educated decision about the kinds of foods and beverages we are consuming."