...And The Liver Screamed "Help!"
Heaping concern on herbal soups, but the main message gets lost.
This week, a scientific study poured herbal soup mixes over liver cells. The resulting media coverage was a little unusual — and maybe even turned people off the popular Malaysian and Singaporean dish, Bak kut teh.
Perhaps there’s a Seinfield joke about soup1 here, but I can’t really make it because I’ve only ever absorbed the episode third-hand. Sorry.
What I can tell you is how and why this study made headlines — and why it’s another good example of poor bad troubling science reporting.
Here’s what happened.
First, I want to shout out that I was alerted to this story twice — once by the fabulous smart people of the Science Journalists Association of Australia2 and another time, just hours later, by friend/mortal enemy and polar medicine doc, Dane Brookes.
In both cases, they pointed out an ABC article headlined:
Bak kut teh herbal soup may cause liver damage and interact with medication, study finds
I love a good “study finds” headline because it means there will be a study linked in the piece, as should be the case with all science writing, right!
Oh, nope. ABC forgot that. That’s okay. The author tells us we can find the article in the journal “Forensic Science, Medicine and Pathology” and doing a little extra tracing, we can go one step further back and find a University of Adelaide press release that dropped on the same day (July 12), headlined:
Popular soup can cause liver damage when mixed with medication
Immediately, we can see the difference in those two headlines is pretty stark. One seems to suggest medication with bak kut teh could cause liver damage, the other suggests it may cause liver damage and also interact with medication.
With this, we begin to pull apart where this story came from and how it came to be presented in this way.
The study was published on June 24. So it’s now a few weeks since it hit the journals. Always good to point out that journalists are rarely scouring every journal (there are way too many) to find stories, so a lot of the science news you see comes via press releases, like the University of Adelaide’s.
Most of the time, the press release will get to a journalist before it’s published on the University website (and elsewhere across the web) and contain a bunch of info about the study. Good practice is to go to the journal article and actually read through it and parse its methodology, getting commentary from other experts.
I decided to do that. First, I went to a Malaysian Cuisine expert, Jackie M, to ask what bak kut teh really is. The articles describe it as a “popular herbal soup” or “pork bone tea” but bak kut teh is a bit more than that and it’s kind of hard to pin it down as one specific dish or concoction.
“First of all, herbal soups is a broader term to describe dried herbal mixes you can buy at traditional medicine shops for use in making broths, and bak kut teh is one of these such mixes,” Jackie tells me.
Jackie notes that Malaysian and Singaporean bak kut tehs differ in the combinations of herbs used for the dish — and, she says, “every bak kut teh fan has his/her own favourite brand of bak kut teh spice mix” and that spice mixes are basically how people make these dishes. They go to a shop and pick out a mix. No one does it from scratch.
As a result, the spice mixes may contain ingredients the average cook is unfamiliar with, Jackie says, and generally there’s not a lot of knowledge of exactly what goes into a herbal soup formulation.
This seems like fair impetus to study them, in case there are ingredients that might be toxic. After one of the authors had a patient present with liver disease, the authors wanted to look into how perhaps the herbal soup formulations might interact with particular drugs (in this case it was statins, which are processed by the liver and are taken as cholesterol-lowering medication. So that’s where the study started — trying to answer the question of whether these formulations might interact with statin.
The team looked at four formulations of bak kut teh, taken off the shelf (and one from a pantry of the lead researcher), throwing them in boiling water for five minutes. Across five dilutions, it found that all 4 formulations did kill liver cells in culture, with one destroying up to 83% of the cells. Seems bad!
But there’s a lot of caveats here. As one liver specialist told me, it’s a very big leap to go from “these formulations killed liver cells in the lab” to “bak kut teh can cause liver damage.”
Getting to that point requires a far more rigorous investigation.
The paper doesn’t analyse the indiviudal ingredients present in the formulations, which leaves the door open for contamination that might have occurred or changes to the formulations as a result of storage. Maybe even where the formulations were stored changed them as did how they were transported. And the soups are usually also mixed in with meats, such as pork and chicken. Does this alter them in any way? None of that is really established in the study.
Another point: Many people across Asia enjoy bak kut teh and have been doing so for decades and there’s no analysis of how common liver failure is in these populations compared to populations that don’t eat bak kut teh. And what about the different formulations between the Malaysian dish and the Singaporean dish? There’s just so many questions.
Thus, condemning bak kut teh is problematic and troubling.
To be fair to the original study, the authors point out more research is needed to evaluate associations and suggest herbal soups should be considered during autopsies where there’s liver damage or liver failure. They note natural dilution of the soup within the stomach may alter the risk of toxicity.
But the major concern I have with the reporting about this study is that it’s reminiscent of the MSG scare that began decades ago and still permeates culture today. In the 1960s a doctor wrote in the New England Journal of Medicine he had experienced heart palpitations and weakness after eating at a Chinese restaurant. He dubbed it “Chinese restaurant syndrome.” It’s unclear whether the letter was a hoax, as some have claimed, or something else (There’s a great American Life audio story about this) but lots of research has shown MSG isn’t harmful… yet the belief still exists, particularly in the US.
I’m not saying this single study quite exists at that level or has reached critical mass to make people wary of bak kut teh and there is clearly reason to look into how some of these herbs (many unknown as Jackie points out) might interact with the liver or other parts of the gut and how they interact with medications, too.
However, in performing this kind of work — and writing about it as a press release or news article — you can inadvertently demonize a dish and a culture. One of the researchers tells me they’ll now look at specific chemicals in formulation for interactions.
So, as Seinfield’s Soup Nazi says (apparently),
“Come back. One year” and we’ll see how the study fares.
The image featured as the header in this article is created by the Midjourney AI from a prompt “Diagram of a human liver, renaissance, classical style” … the middle four images are what I got when I asked for “a liver screaming ‘help!’” ….
The Adelaide Advertiser did make it with their social headline "“No soup for you — it could be very nasty”
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