JOHN YANG: For centuries, people in Southeast Asia have used the leaves of kratom trees as a home remedy to soothe nerves and ease pain.

Recently, its popularity has exploded in this country as a way to alleviate anxiety and the effects of opioid withdrawal.

These products are widely available at smoke shops at gas stations, but kratom is poorly regulated and synthetic versions contain high concentrations of a powerful compound that U.S.

officials say should be restricted.

Ali Rogin takes a look at this controversial herbal drug with Kirby Wilson, senior politics reporter at the "Tampa Bay Times."

ALI ROGIN: Thank you so much for being here.

Let's first talk about what kratom is, how it's traditionally been used in other cultures, and how it's showing up here in the United States.

KIRBY WILSON, Senior Politics Reporter, Tampa Bay Times: Yes.

So kratom is a very interesting substance with a long history.

It's a tree that's grown in Southeast Asia, primarily in Indonesia.

And it's been used there for centuries as a medicinal sort of home remedy for a variety of ailments from an analgesic pain treatment to curing indigestion.

And so it's brewed into teas.

There are a lot of the indigenous people in Indonesia see it as sort of a cure for what (INAUDIBLE) kind of thing.

It is not legal to import into the United States, but it gets here anyway, and people use it here for a little different reason.

ALI ROGIN: Yes.

So tell me about that.

You've reported extensively on this specifically about how it's showing up around the Tampa area in Florida.

But what have you found in the course of your reporting on it?

KIRBY WILSON: It's been an interesting sort of dovetail with the opioid crisis in America, because there have been a lot of people that have been seeking treatment for that particular affliction.

They get addicted to painkillers, and they want to weigh out, but they don't have an easy resource.

So people have used it to wean off of opioid addiction, which is honestly probably a societal good that they find somewhere to turn that isn't another street drug or back to opioids.

But the problem with it is that this is, in a lot of places, is entirely unregulated.

And so people are using the substance that had been used for centuries for a completely different purpose in a way that authorities aren't really getting their arms around or sort of understanding.

And the -- there's not really well established limits on dosing or what -- how much is wise to use, what form of it is wise to use, and in what circumstance.

ALI ROGIN: Why is it, Kirby, so difficult to regulate kratom products?

KIRBY WILSON: Really for the same reason it's so difficult to regulate anything.

It's difficult to know the exact science of how things work on the body.

Still, dosing limits are poorly understood in general, because everybody's body is different.

So doctors have some sense of how much of a certain drug could harm or kill a person.

But that is -- that has only understood after extensive clinical trials and testing and scientific evidence.

There is great promise.

Don't get me wrong.

I'm not here to contribute to some sort of panic around kratom.

People are using it safely, and it is benefiting them for sure.

But they are using it in an off label way.

And when you're using anything in an off label way, dangers are present.

And especially when there is an industry that is incentivized to create the most -- the most concentrated possible iteration of this substance that people are using as a medicine, that's when you run into trouble.

ALI ROGIN: So let's talk about those iterations.

Let's talk about the difference between kratom the plant and some of the compounds found in it, which appear in different levels of concentration in some commercial products.

And then there's another factor of this, which is the synthetic versions of those compounds, which I know is kind of in its own category right now.

Walk us through all that.

KIRBY WILSON: Yes.

So the thing that's been in the news most recently is a product called 7-hydroxymitragynine, which is a -- or mitragynine you might hear it pronounced, which is a -- an alkaloid of the kratom plant.

Basically, it's a chemical that's found in the natural kratom plant at very low doses.

Scientists who have studied this chemical are worried about its potential for abuse and addiction.

It mimics opioids in the way that it interacts with our brains.

And it may contribute to respiratory depression, which is ultimately what kills people when they overdose on opioids.

So the Trump administration and some -- even some states like Florida have said, no more 7-OH, which is the street name for 7-hydroxymitragynine, no more 7-OH.

It's banned.

We're taking it off the streets entirely.

Set that aside because there is a whole other legion of kratom products that are not 7-OH, that are sort of akin to what you'd find in a traditional kratom tea.

If you go to a kava shop, you can get a kratom tea and it's more or less similar to the product that people have been drinking for centuries in Indonesia.

Then set that aside, and there are these other kratom products that are not 7-OH, but have highly concentrated forms of mitragynine, that is the operative ingredient in kratom.

And the effects of that are sort of unknown when it comes to these high concentrated products, but they exist and they're basically ubiquitous anywhere.

Anyone can buy them online in almost any state.

ALI ROGIN: And the federal government and some of these state governments have made a distinction between the kratom product itself and the synthetic derivations of it.

Is that the way to deal with this?

KIRBY WILSON: Yes.

I think it is wise to break off and regulate the two as dissimilar products because even the kratom industry, which I've reported on pretty aggressively and critically, says that 7-OH shouldn't be offered as a product.

So if you're concentrating that and putting that into a product, almost everyone who's reasonable in the kratom space thinks that there is at least a major -- a major problem with that.

As far as the other kratom regulations go, you know, there's reasonable minds can disagree about how best to do that, but the urgent -- and the urgency is certainly there because people, again, are using a product that is not a drug like a drug.

And so there are always dangers that are going to be inherent with that.

But the uptake of kratom is so widespread throughout the country that there would be a lot more harm than we have found if it were as dangerous as opioids.

ALI ROGIN: Kirby Wilson with the "Tampa Bay Times."

Thank you so much.

KIRBY WILSON: Thank you.