Milk thistle testing, explained by Prof. Nicholas H. Oberlies: the full interview

Could you start by introducing yourself: what you've worked on, and how you came to specialise in the analysis of medicinal plants?

Sure. My name is Nick Oberlies, and I'm a professor at the University of North Carolina at Greensboro in the Department of Chemistry and Biochemistry. How did I get into this? I earned my PhD almost 30 years ago. I work on the isolation and the structure elucidation of bioactive compounds. What that means to your listeners is, whether you're talking about an herbal remedy, or you're just going to the pharmacy to get a medicine, let's say a penicillin, or let's say you're going through cancer therapy: many medicines, I believe it's 25% in the United States, 25% of all standard medicines, whether they're behind the counter or over the counter, are derived from nature. And if you look in the anti-infectives, antibiotics or antifungals, or the anti-cancer space, it's more like 60 to 65%. So nature has been a big treasure trove of bioactive molecules that people figured out have some purpose. My long-term goal has always been, and it continues to be, to discover molecules from nature that we can use as drugs.

So how did I get into herbal remedies? In the United States, herbal remedies are regulated much differently than what we would call standard medicines. It's different than most of the world. In the United States they're basically sold by the community. It doesn't go through the Food and Drug Administration, other than the food side; it doesn't go through the drug side. They're not patented, anything like that. So the way we got into that business is: people that are trained in what I do are very comfortable working with mixtures of compounds. And herbal remedies are by definition a mixture of compounds, and they needed people to analyse those mixtures and figure out how much of each compound. If you're going to figure out how much of each compound is in there, you need what are called reference standards. You've got to isolate some compounds and determine their structure. A lot of what we do is determine how all those atoms are connected. And the flavonolignans, those that are in milk thistle, are particularly tricky. In the early 2000s we were approached by some colleagues to do that process. We were working with many colleagues; we isolated the compounds, determined their structures, and measured them in a whole bunch of different products. That's kind of how we got into milk thistle.

I should tell you, and I don't know if you'll love this answer or not, but I always tell people, when it comes to herbal remedies: I don't care. And some people get offended, like, what do you mean you don't care? Well, there could be an equal number of people in the population who think milk thistle is the most awesome thing ever, it's great for me, it's wonderful. And there's other people who think it's nonsense, it doesn't work at all. I don't care. What I do care about is that if somebody sells something that's labelled as milk thistle, it should be from that plant, and it should have a series of molecules in it that are supposed to be there. And it should be safe, right? I've watched a few of your videos, and it seems to me to be very much about the safety and the quality of herbal remedies. That resonates very high with me: the safety and the quality.

Now, let me just say one more thing about milk thistle. Even though I said I don't care if it works or not, it's on my list of things that probably work. I think it probably works. These are US numbers, I don't know global numbers. In the United States it's almost never in the top five of sales, but it's usually always in the top ten. And it's been around for thousands of years, going all the way back to ancient Greece. So I think it probably works.

You said what you do care about is that when someone's selling a milk thistle, it is milk thistle and it has compounds within it that match a reference standard. One of the things that interests me at the moment is an HPLC testing method compared to a UV testing method. From what I understand, HPLC, which is used by the pharmacopoeias, will isolate those individual compounds within silymarin and quantify them, whereas UV doesn't do that. What are the pros and cons of those different testing methods?

I'm not familiar with the UV version. I'm very familiar with the HPLC version. So for your listeners, HPLC is high performance, or high pressure, depending on how you want to call it, liquid chromatography. And the chromatography means you're going to get a series of peaks. With milk thistle there are four major compounds, but usually we get as many as seven different compounds when we do the analysis. These are called flavonolignans. What that means is they're part flavonoid, and they have what's called coniferyl alcohol that's hooked up in a lignan-type bond. That's why they're called flavonolignans. These are well known to be in this plant. It's almost like a thumbprint: the thumbprint of this plant is a series of these flavonolignans.

I think the HPLC method is really important because they all have almost identical molecular weight. One way we measure things is by HPLC mass spectrometry, and mass spectrometry is measuring the weight of compounds. You can measure that way out to four or five decimal places. If you know that molecular weight, and if your listeners know about the periodic table, we know atoms can be measured out to many decimal points, you can sort of put together what the molecule is. But when they're all the same molecular weight, it's hard to say what they are unless you can separate them. Separate them into different ones.

So the UV method that you're talking about, I presume, is probably just looking at the extract and taking a UV spectrum of the extract. These molecules do absorb light really well, because they have what are called double bonds, and these double bonds absorb UV energy really well. So they have a very unique profile in the UV spectrum. But that UV spectrum profile is almost the same for all the molecules. So what I would say is that the HPLC, or the HPLC mass spec, is a more refined way to measure it. Both measurements may or may not be accurate, but the one that is more in line with technology in 2026 is the HPLC method.

I spoke to another chemist, based in Hungary, who does a lot of testing of supplements, and he said exactly the same thing. And the pharmacopoeias use HPLC for milk thistle, right? This is the standard.

I believe so. When it comes to the pharmacopoeias, the one I'm familiar with the most is the German Commission E. It's right on this bookshelf over my right-hand shoulder. I'd have to look it up real quick, but I imagine that they often use that. It's not to say that one is worse than the other, but one is probably more advanced than the other, is what I would definitely say. Sometimes with herbal remedies, some people make the point that there are things you can do to measure different constituents that were cutting edge, let's say, in 1975. But they're not cutting edge in 2026. That doesn't necessarily mean they're inaccurate. They're probably pretty close. They're probably within plus or minus 30%. I have a really good colleague who is an expert in analytical chemistry, and she always says plus or minus 30% is about the best we can do, especially if you want to compare measurements between labs: if I did one in my lab, versus you did one in your lab, and somebody else did one in a different lab. If they're within 30%, they're usually pretty close.

I think we did one where we had a silymarin reading of about 40 milligrams, and that was HPLC, and then the UV was about 80. So that's not...

A little bit more, though.

Yeah, because plus or minus would be 30%.

The individual compounds within silymarin: am I correct in saying you were actually the one who isolated some of them?

Yep. It's kind of a tricky thing. The cool thing about the literature of milk thistle is that it goes back to the early 1960s. Some very famous scientists from Germany were working on it. If you look at the names of the individual constituents: silybin A, silybin B, isosilybin A, isosilybin B, and then there's silychristin and silydianin. It's my understanding that this chemist had two secretaries, one whose name was Kristi and one whose name was Diana, and that's how he came up with those other two names, to give an homage to them. So that goes way back to the 1960s.

If you don't know a lot of chemistry it's hard to explain, but the way those molecules are put together, they're called diastereoisomers. It's kind of like your left hand and your right hand. If you take a glove that's made for just your left hand, like a baseball glove (you guys don't play baseball in England, but you probably know what a baseball glove is), and you try to put it on your right hand, it won't fit, even though it's still got a thumb and four fingers. Same with your shoes: you can't take your left shoe and put it on your right foot; it doesn't really work properly. Well, that kind of thing happens with molecules, and that's really important, because that's like a lock-and-key mechanism. I can take my right hand and shake your right hand, but it's hard to shake your left hand with my right hand. It's the same kind of thing.

So what we did in the early stages was we were able to isolate all those individual isomers, and I'm not so sure anybody did that before us. The other thing we were able to do is we crystallised one of them. There are many ways you can characterise a molecule: nuclear magnetic resonance, mass spectrometry, UV like you just mentioned, infrared light. But in all of those things you're kind of inferring the structure, and with X-ray crystallography it's almost like you're taking a photograph of the structure. One of the most famous publications from the 20th century is the structure of DNA, Watson and Crick from England. One of the key pieces of information they had was a crystallography structure. Getting that photograph of the structure really nails it. I always tell people it's like if someone were robbing your house: you might have fingerprints of them, and from the fingerprints we could infer that this person came and robbed your house. But if you had a webcam and you saw the picture of the guys stealing your television, you've got the photograph, and you show it to them and say, hey man. That's what X-ray crystallography was. We were the first to do that in the early 2000s, to get an X-ray crystallography structure. And from the one, you could infer all the others.

So that was what gave you a photograph of all the compounds within milk thistle, essentially. Some of them have then gone on to be developed into drugs?

Not by my lab they haven't. We studied them for a long time for different disease states, including cancer, particularly prostate cancer. Let me ask you, so that I don't talk the whole time: what do you think milk thistle is mostly used for as an herbal remedy?

Liver support, right?

Liver support, okay, cool. Just making sure you weren't thinking of some other thing. I always tell people that if you mess up your liver because you've got hepatitis, or you ate a poisonous mushroom, or you drank too much, I think milk thistle works for this purpose. There's a lot of evidence that it works to regenerate your liver. At the same time, by the way, you'd have to stop drinking. But if you've really whacked your liver for those kinds of reasons, there's a lot of good evidence that it works. There is a preparation of it that you can buy from Germany, which I think is called Siliphos. In Europe and in England these things are sold way differently than the United States, so they're more sold like drugs. I believe there are formulations of it that have been refined. But I want to make it clear: I don't think the work we did led to one of these drugs. Somebody else pushed that stuff forward.

How could a consumer tell if they're buying a good milk thistle supplement?

That's a great question. I don't know about in England, but in the United States they've changed recently. In the last five years we've seen super-high-dose versions of silymarin. Have you seen that as well?

Usually what we get is extract ratios. I know you guys have different laws around that: if it's a 200-milligram dose of a 10-to-1 extract, you can only say the 200 milligrams, right? Here, you can say the big number. So you can say milk thistle 10,000 milligrams, but it's got 100 milligrams of a 10-to-1. And there's no third-party testing of any silymarin content. I think it could be very misleading when the consumer sees 10,000 milligrams, it must be strong, but it has not got the silymarin.

That is a tough question, man. Let me be clear: I get that question a lot, not just in interviews, but friends, or my parents' friends, asking me how do you know if you've got a high-quality product? On the one hand you could say, well, I'd buy it from a trusted source. This is universally true for any herbal remedy. In the United States there's a whole bunch of things that are sold at a gas station, right there at the counter. I wouldn't consume that. In fact, we recently did a study on one of those, and I opened it up and saw what it was, and I thought, oh my God, I can't believe this is legal. It's really bad stuff. This is not a milk thistle product, it's a different product. So buy it from a trusted source. And I hate to say this, but I think usually ones that are priced a little bit higher are usually probably higher quality. Now, if you're somebody who wants to sell a low-quality product, you could just say, I'm going to raise my price. But I think: the trusted source, and I would look on the back and see if they've measured silymarin content and they give a number.

And then you might ask, well, what if they give a UV number versus a mass spec number or an HPLC number? Oh man, I don't even know about that. I wish I had a good answer there, but I think I'd be looking for a trusted source, that they didn't spend all their money on marketing, that it seems like they put some science to it. And then in the United States we have people who are experts in that kind of thing; they're called NDs, naturopathic doctors. I might talk to one of those people, somebody who's got experience treating lots of patients. In the United States, your average medical doctor that you go to for a general checkup probably does not have a lot of experience with herbal remedies. They're not trained in that at all. So I might find somebody who's trained in that to give me some advice. It's not clear, man. It's not clear.

It's a minefield, isn't it?

It is a minefield, yeah.

I would also say, let's just say you're going to take an herbal remedy. I wouldn't hide it from your medical doctor. Let's say you've also got a heart condition, and you're taking some medicine that your cardiologist is prescribing to you. I would make sure that your cardiologist knows that you're also taking this other thing. To be honest, a lot of the work that we've done over the past decade on herbal remedies, broadly defined, has been looking at what we call herb-drug interactions. You're taking whatever medicine. It could be cancer medicines, it could be birth control, it could be heart conditions, it could be antibiotics. Whatever it is you're taking, nobody requires the herbal remedy company to figure out what sort of drug interactions it has.

I don't know if you know much about things called cytochrome P450s. These are enzymes that are in your liver, but they're also in your GI tract. Any time you consume, let's say, an antibiotic, it is known how it is metabolised in your gut. Now, people are different: if you're from European ancestry, or African, or Asian, Native American, what have you, there is a range. Men are different than women. Ranges matter. So if a pharmaceutical company puts a new drug on the market, it is known how that is metabolised. That's how they figure out that you, being roughly 70 kilos, take this dose three times a day for five days. That is not the case for herbal remedies. Nobody really knows how those things are metabolised. So we've spent some time, funded by the US government, thankfully, to figure out how certain drugs are metabolised, and would the metabolism of one thing affect the metabolism of something else. This polypharmacy thing.

My strong advice to anybody is to be very careful about polypharmacy. It's a bad habit in the United States to take too many medicines. My own parents went through this as they got older. I remember working with their doctors, like, can we rule a few things out? Do they need to take this anymore? For instance, my parents were going through cancer chemotherapy, and they were also taking statins. I remember the oncologist, a very, very bright oncologist, said: Mrs. Oberlies, I don't think we're worried about your heart condition right now. I don't think we're worried about your cholesterol level. Why don't we take this out of the equation? Because it's metabolised a certain way, and it might affect the way... all those things are in concert with each other. So let's try to minimise what we're doing.

I told you that I don't care if herbal remedies work or do not work, but I'll tell you that I'm into exercise, I'm into nutrition, and I don't take a lot of medicines. I don't take any medicines, to be perfectly honest. And I'm going to try to avoid that for as long as possible in my life, because I worry about how those things interact with each other and what that does to your body. So, back to your question. You're going to take milk thistle. Take it for a reason. You got some sort of liver problem, you got hepatitis? Okay. You're probably working with some sort of internal medicine person who's dealing with the viral part of hepatitis. Make sure they know you're taking milk thistle, so that we can mitigate what's going on with the metabolism of milk thistle and the metabolism of whatever drug you're taking, to make sure they work together.

What about companies that provide third-party testing for, say, milk thistle, with HPLC, with the silymarin reading, and ideally even for the batch that you're taking? Would that be a good indicator?

Wow. I mean, can your average consumer afford that, though? It's not cheap to get third-party testing.

Sorry: if the brand has provided it.

Oh yeah. I think the brand providing third-party testing is probably a good idea. Those third-party testing labs, there's always a way to game the system, but I think the well-known ones do not, and they're built on their reputation. I always tell my students, I train graduate students, you'll have a good life, but you're not going to make bank. If you want to make a lot of money, go be a banker, go be an investment guy. But the one thing you have in life is your reputation as a scientist. That's why I'm very cautious about what we have done and haven't done in science. I want to be very clear what our contribution was, because I don't want someone to think I was inflating what we've done. And it's the same with any third-party testing company. People come to them because they've got a reputation for doing the science well.

Let me go back to another question. You asked me how do you know which ones to buy. It's easy for me to tell you the ones I'd avoid, not the ones I'd buy. I'd avoid the ones that are sold right there at the cash register at a gas station. I would also probably avoid the ones that are geared for the bodybuilding industry, the ones that are going to pump you up and build your muscles and all that. I have been involved in some studies of those where I think there is a very, very grey line of what they're putting in some of those products, especially when it's a giant mixture. By definition an herbal remedy is already a mixture. So if somebody then wants to mix milk thistle with four or five different other herbs, I would definitely avoid that. If I was going to take milk thistle, I would take milk thistle. Period. And that should be an extract of the seeds; technically speaking they're called achenes of milk thistle. That's what's been around for 6,000 years. Not some mixture of it with green tea, and also mixed with 15 different vitamins, because it's going to pump up your veins and all that jazz. I'm going to guess that those people are probably not listening to your podcast, unfortunately. But if they happen to be, or they know somebody who's into that, man, I would avoid that stuff like the plague. It's a very slippery slope.

Another scientist I spoke to in Hungary did a third-party testing investigation into male enhancement supplements, natural sexual enhancers, and he found Viagra in them. Because the customer would have taken it and seen a result and gone, well, this stuff works, I'll keep buying it.

Exactly. And that's illegal, by the way. You're not supposed to do that. That is completely illegal. And then you've got to ask yourself: let's just say there's Viagra in there. It's measured; I'm going to presume this third-party lab has a standard, they can verify it by the thumbprint, it's the right compound. How'd that compound get in there? Who the heck made it? What's the quality on that product? Life is short, man, and human life is precious. Do you really want to mess with your body with that stuff? So yeah, I would avoid all those sex-drive ones. I think all of that is Mickey Mouse. I'd avoid all the ones that are for bodybuilding. I'd avoid all the ones that are sold at gas stations, or anything else that's kind of untoward like that. So that leads you to: okay, I want to embrace these things. Get yourself some good advice from a reputable company, a reputable place that's selling them, a place that's got to keep its reputation for selling it. These companies that are selling it at a gas station, if suddenly somebody says, oh my God, that's illegal, and they get in trouble for it, they close the business.

Make a new one.

They make a new one. They get a new PO box. They get a new name for the corporation. They give it a name that sounds like it's halfway legit. You can't catch them. It's a real problem.

If you could change one thing about how milk thistle products, or supplement products in general, are regulated, what would that be?

That's a great question. No one's ever asked me that question. What I would change is I would make them quantify. And by quantify, I mean measure. Measure the constituents. It doesn't have to be all the constituents. But with milk thistle it's pretty well established that it's either four or seven, depending on how you want to count. And I would want to have the box that says on the back: here are these seven constituents, and here's their amounts. And I would do the same thing with goldenseal; green tea, it's well known what the compounds should be in green tea. You can go down the list of all these ones. I would say you have to measure it and tell us what it is. And I don't think that's a heavy lift.

Now, some people would argue against that. They would say, yeah, Nick, but nobody knows that those seven are actually what's helping the person's liver. Because if you ever saw an HPLC chromatogram, there are things that are in very small amounts; they're like in the grass. With milk thistle, the flavonolignans are the big trees sticking up out of the grass. There's a bunch of things down there in the grass. You don't know that it's not all these little minor constituents that are actually causing the effect. And I would say: you're right, I don't know that. But if you can measure those seven reproducibly, then it's a reproducible, what I would call clean, safe product, over and over again. If I was in charge, that's what I would make people do.

I would also guess, by the way, if you talked to anybody who's got a reputable herbal remedies business, businesses that have been around for decades, 20, 30 years, they wouldn't argue against that. Because any time there is an article in the New York Times or some prominent publication that says all these things are just a bunch of snake oil, what happened was somebody bought some malicious product from a gas station, designed for bodybuilders, for male enhancement. Everybody suffers when that happens. So the reputable companies will avoid that. There's a nonprofit in the United States called the ABC, the American Botanical Council. You might want to interview them someday. They've got a program called the Botanical Adulterants Program, something like that. I think that was born from a bunch of people getting together and saying, we can't force regulations, but we can all agree to not have these adulterants in there. And they publish a series of monographs that I think are very helpful. Maybe the project's been going on for 10 or 15 years. That kind of noble, let's all get together as a community and try to squeeze out the bad actors: I think that's a good idea.

Similar to what I'm trying to do with my channel. I'm testing brands and publishing the results to try and clean up the industry and get better products for people.

That's good. That costs you money. Out of your pocket.

Costs a lot of money. All sorts of legal headaches as well. But I think it's a good thing.

Does the source of the raw plant material, where it's grown, where it's harvested, affect the constituents?

That's a great question. The answer is yes. I don't know if that's true with milk thistle as much, because almost everybody works on the seeds. And that means the seeds are collected when it flowers, which is a pretty defined period of time. But I had a friend in graduate school; we were working on this plant called Asimina triloba, also known as pawpaw. This was more for drug discovery purposes, and we were collecting samples from the twigs. This was in Indiana, in the middle of the country, near Chicago. She did a study where she looked at the biological activity of samples collected from, I think it was two different trees in one plot, the east side and the west side. They collected a series of twigs and did a study for 12 months. And not surprisingly, the level of the bioactive constituents went up in May, June, July, August, and come September, October, November they go down, and they plateau November, December, January into February. Then March, they start to come up again. It totally makes sense. The plant is dormant. But when the spring happens and now there's insects around, the plant is probably making these compounds to protect itself from herbivores or insects, whatever. So there's this natural cycle that happens with the twigs and the leaves in temperate environments. In a tropical environment I don't really know. It's going to depend more on the plant part where you'll see variability.

Also, there are pretty well-known studies with olive oil where they can look at key constituents based on where the olives are grown. Greek olive oil is very different than Spanish olive oil, and both of them are different than one that's grown, let's say, in the Middle East, let's say Jordan. There are a series of marker compounds that are going to be different based on where it's grown. Again, with milk thistle it would be less of an issue, because the seeds happen when it flowers, so you're locking into a really defined period of time. But I imagine there could be some variability.

Going back to your other question, about if you could make the rules and make it safer: the other thing I would add would be to check against pesticides, herbicides and also heavy metals. You can get really cheap land near Chernobyl, right? And you could grow plants. Now, nobody would do that; it's blocked off, some of it's a war zone. But it is known that certain plants can bioaccumulate things from the environment, like heavy metals. When we were doing some studies for this project funded by the US government, by the National Institutes of Health, we eventually did human clinical studies. To do a human clinical study takes paperwork that is taller than I am. We did all kinds of things to verify: here's the series of marker compounds that we would see in this herbal remedy. We bought the exact same lot. We made sure we had enough material that we could carry it through the entire clinical study, which is probably two years. We had to check to make sure the shelf life was good. All kinds of things that are right in the Oberlies lab wheelhouse as chemists. And then we had to also figure out pesticide contamination or any heavy metal contamination, which is not something we do all the time. So we had to go to a third-party lab and have all that stuff measured. This was as mandated by the FDA. The FDA had to give us approval to do this human clinical study, and they said, all your chemistry stuff is good, but we also need to know these things.

So yes, again, if I were in charge and I was going to sell herbal remedies, they would have a series of key marker compounds that are well known for that herbal remedy. And they would also check for lead, cadmium, Roundup, whatever pesticides you can think about, herbicides you can think about, and they would be below a certain threshold. And these marker compounds would be in there, and then you'd have a nice safe product. If you can find that on the back of your package that you buy at a reputable pharmacy or reputable grocery store, somebody that you're interacting with, maybe that's a pretty good product.

I think that's the way it should be.

I don't really know the regulations in England, but a lot of times in the United States we're comparing regulations to Canada, because it's our neighbour, and to Germany, because Germany has a long, long history in regulating things. It's my understanding that some of the German codes for what an herbal remedy is are like: if you're going to call it this, it has to be that. And I think that's the way it should be.

[A passage here, in which I explained that the UK's Traditional Herbal Registration scheme requires a manufacturer to prove a product's quality to the regulator, was garbled in the captions and can't be quoted reliably.]

Prove that your product is legit, and I imagine a bunch of third-party testing. That's not surprising; that's pretty similar to what's going on in Canada. Because you guys are cousins as well. So I think maybe, because of those legal regulations in your country, your products are better there.

The problem is you don't have to be in this THR to sell milk thistle.

And it's probably more expensive, right? To buy it on the shelf.

I don't know about to the consumer. I know that to apply as a manufacturer to get a licence is a whole big thing. It'll take years and cost hundreds of thousands.

But does the consumer know, when they're buying it, that it is THR versus it isn't? Does it say on the package?

It does say on the package, but how many consumers will even know what that is? Probably very few.

So my advice to the consumer is buy that product, even if it costs more. It's probably better for you. I think in the UK, THR for sure.

Is there a question about milk thistle that you wish someone would fund research to answer?

One of the things we're interested in in the United States is these really, really, really high-dose products. I don't think anybody's really studied the safety of those. Not only do I wish, we've applied for grants to do that. We haven't won them yet. So if there are any grant reviewers out there, look, I think it's an important issue. So that's one thing. And I have crazy ideas with milk thistle. I wish someone would fund me to study if milk thistle would help people with liver transplants. That's just a crazy idea, and it's probably a bit of a dangerous idea, because somebody who gets a liver transplant is probably on a lot of other medicine; they're taking a suppressant to suppress their immune system. By the way, the molecule that they're taking to suppress their immune system is derived from nature, called cyclosporine. And because their immune system is suppressed, they're probably really susceptible to the common cold, or COVID, or things like that. So there's a lot of things there, but you could study it in animal models and figure it out.

I remember bringing this up once at a conference, and there was a guy sitting next to me who was an MD. I've got a PhD; this guy's an MD, a medical doctor. I was ready to go, and he kind of touched me on the shoulder and said, you know, we've got to be careful about this. These are sick people. But that was also 20 years ago, when this idea was coming around, and I think transplants are one of those things that are only becoming more common by the year. You can envision that eventually we might have transplants that could be coming from animal models, from a pig to a human, or something like that. So yeah, if you had a lot of money, I could design some experiments around that.

Most of the time, the work that I'm doing on milk thistle is somebody with a biological question, cancer, drug metabolism, antiviral, you name it, comes to me and says, man, that chemistry is a lot more complicated than I thought. Can you help us with the chemistry? So on almost all of the studies we've done with milk thistle, we're kind of like the sub to the person who's got this biological question. And it is our job to make sure that whatever biological question they're testing, the chemistry is the same and well-defined every time. I feel like that's a thing that gets missed, because a really well-designed scientific study should be reproducible. All the facts should be in there, so that you could reproduce it. And if the thing is, oh, we just bought that at a gas station, I don't even know the name of the product we bought: it's not reproducible. So we're the one who says: aha, we got this well-defined product, and here's the lot number, and we checked all these parameters, and we measured all of these things. All those things that I told you I wish the consumer knew, we've measured all of those, and we've done it in far more detail than your average consumer needs. And thus, if somebody was going to reproduce the study, they could go about doing it.

That's something I've wondered so many times. I see all the research published about different supplements, but to what extent have they tested the compounds within that supplement, to be able to reproduce it?

I'll tell you the trick to that, as someone who's reading a scientific paper. Typically the chemistry will not be in the main paper, if it's a biology paper, if it's in Nature or Science or some paper like that. But look at the supporting information. Every publication will have what's called supporting information, and the supporting information is usually free to download. Even if you've got to pay for the paper, the supporting information should be free to download. In that supporting information, look for some chemistry data: HPLC, UV, NMR, mass spectrometry, any one of those things. And then look at the addresses of the co-authors and find the chemist. He or she probably put that information in the SI, and that will tell you if it's more reproducible. Good journals, reputable journals, will require some of that information, this backup, to say that it's not just something that somebody bought off the shelf.

That video that got 200,000 views was third-party testing a brand in the UK. They're selling on TikTok Shop a lot, super, super cheap. I emailed them and said, do you have any third-party testing? And they said no. So I said, okay, for a brand their size, they should have that. A few months went by and I emailed them again saying, do you have any now? And they said no. So I thought, I'm just going to test it and see what happens. The ashwagandha was low. The milk thistle should have been 80 milligrams of silymarin; it was actually 40 or 45. They then came back and said, oh, HPLC isn't the right method to analyse it, UV is.

So yeah, I'm with you. And I disagree with that point.

Milk thistle has paid a lot of bills at this place. So I'm a big fan of milk thistle, even if I don't take it, because I presume my liver's in good shape. And I appreciate you putting out YouTube videos like this. I wish YouTube existed when I was first starting out as a scientist. I tell my students all the time: there's a lot of good information on YouTube that can help you learn something, at least to get started on an idea.