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Tips for reading news about tea studies
As Dr. Oz is being thoroughly (and rightfully) shredded by the Senate Commerce, Science, and Transportation Committee for pimping weight-loss scams, we shouldn’t lose sight of the fact that (a) there are a lot of valid health benefits to tea, and (b) virtually every news story about tea and health manages to misrepresent or misinterpret the scientific study they’re describing.
As you read articles about tea and health, it’s important to keep in mind that the person writing the article is usually not the person (or people) who actually performed the study it references, and that the reporter/blogger may have read only the summary, not the whole study. Also, in larger news operations, the person writing the headline isn’t the same person who wrote the article, and if they’re operating on a deadline, the headline may not accurately sum up the story.
Tip 1: Beware of extreme claims
There’s an article on Authority Nutrition entitled,”How Green Tea Can Help You Lose Weight Naturally.” It’s worth reading. There are good explanations of the benefits of tea, and it cites dozens of actual scientific studies. But any article that begins with a statement like “green tea is the healthiest beverage on the planet” should set off alarm bells. No, there’s never been a study that tested every single beverage on the planet (there’s never been a study of every style of tea on the planet, for goodness’ sake). No, we don’t have a generally-accepted definition of “healthiest beverage.” An opening sentence like that one tells you you’re about to read something sensationalistic, and you should view everything they say with skepticism.
Any article that begins with a statement like “green tea is the healthiest beverage on the planet” should set off alarm bells.
Tip 2: They only studied what they studied
There’s an article on Byron J. Richards Wellness Resources entitled, “The Effects of Green Tea on Weight Management.” The author is a Board Certified Clinical Nutritionist, the studies cited all appear to be properly-conducted randomized controlled trials, and the conclusions all appear to be valid. So what’s the problem? Reading this may make you want to rush to your tea cabinet and throw away all of those white teas, oolong teas, yellow teas, and pu-erh teas. You need to replace those all with green tea, right. Wrong!
The studies looked at green tea. Specifically, they measured catechins and caffeine in green tea. They never compared green tea with white tea — or any other kind of tea. White tea may be even better for weight loss. So might oolong, pu-erh, or yellow. If green tea is measured against anything else in a study, it’s almost always black tea. What’s the difference between green and black tea? Black tea is oxidized, and that process converts a lot of the antioxidants into other compounds (catchins are a type of antioxidant). But white and yellow tea isn’t oxidized, and oolong is only partially oxidized. Shu pu-erh is oxidized and fermented, and sheng pu-erh is fermented without being oxidized first. Don’t draw conclusions about your oolong from a study that never even looked at oolong!
Tip 3: There’s more to tea than antioxidants
I think it’s pretty universally agreed that antioxidants are a good thing, but they aren’t the only source of health benefits in tea. When I got in a tiff with Fox News’ Chris Kilham about misrepresenting studies, it related to a study that showed coffee had some great health benefits. Reading the study showed that it looked at one thing: caffeine. All of the health benefits it listed for coffee would apply just as much to tea, guayusa, yerba maté, or Mountain Dew. If you like black tea, don’t let yourself get talked out of drinking it just because it doesn’t have the same antioxidant content as green tea.
Tip 4: All green tea is not created equal
It’s wonderful to see an article like the one titled, “Green Tea,” on the University of Maryland Medical Center page. It has tons of information, cites numerous studies, and explains potential drug interactions and side effects. But, like all of the other articles, it just references “green tea.” Did they test Japanese steamed green tea like sencha? Pan-fired Chinese green tea like longjing? Or was it roasted (hōjicha), powdered (matcha), shade-grown (gyokuro), scented (jasmine), or rolled (gunpowder)? The Kevin Gascoyne study I referenced in my 3-part series on caffeine found tea caffeine content ranging from 12mg to 126mg per cup. Yes, the most caffeinated tea had ten times as much caffeine as the least. He found a similar range of antioxidant contents. If you want to replicate the results of the study, you have to know what kind of tea they used.
Tip 5: Pay attention to who funded the study
If they had done a study that found that green tea gives people smelly feet, how much publicity do you think that would have gotten?
You can’t automatically discount a study because the funding group had something to gain from it. Tea companies are the ones most likely to fund tea studies, after all. But take a look at “Green Tea Promotes Weight Loss, New Research Finds,” an article on Medical News Today (well, actually, it’s a press release, but they don’t make that obvious until the end). It’s very clear in reading the article that Lipton did the research, and that Lipton is very excited about having done the research. It’s a big company, and their PR department did a good job of really spreading the news about that study.
If they had done a study that found that green tea gives people smelly feet, how much publicity do you think that would have gotten? I always tend to pay a little more attention to research coming from neutral parties, or research that’s been duplicated by neutral parties.
Tip 6: Check to see if the methodology was realistic
WebMD has an article entitled, “Green Tea Fights Fat,” which does appear to actually compare weight loss effects of green tea with oolong tea. But read this sentence from the article carefully: “For three months, the first group drank a bottle of oolong tea fortified with green tea extract containing 690 milligrams of catechins, and the other group drank a bottle of oolong tea with 22 milligrams of catechins.”
First, they aren’t comparing green tea with oolong. Both groups drank oolong tea. In one group, they added green tea extract, and in the other, they didn’t. So this study actually compares drinking oolong with drinking oolong plus green.
Second, the average cup of green tea has 50-100mg of catechins. That means the “extract” they fortified the bottle of oolong with made it equivalent to 7-14 cups of green tea. That’s a lot of tea!
If you have specific reasons for controlling your intake of caffeine, L-theanine, catechins, and other components, then there’s plenty of research to plunge into. Focus on people who actually study tea rather than folks like Dr. Oz or Oprah. Look at the paper and see what they actually studied. If it doesn’t apply to you, move on to the next one. If it does, take it at face value without trying to overgeneralize.
But if you’re just looking for a healthy drink that tastes good, stop worrying and buy more of what you like the most. You’re likely to drink a lot more of a beverage you love than one you don’t. If you like to experiment, all the better! If you drink a wide variety of tea, you’ll get a wide variety of nutritional benefits, and you can enjoy yourself as you do it.
Teas, Tisanes, and Terminology
Foliage of a Camellia sinensis bush — the plant that “real” tea is made from.
Language evolves. I get that. Sometimes changes make communication easier, clearer, or shorter. Sometimes, however, the evolution of the meaning of a word does exactly the opposite. The subject of this blog is a good example.
The word “tea” refers to the tea plant (Camellia sinensis), the dried leaves of that plant, or the drink that is made by infusing those leaves in water.
The word “tisane” refers to any drink made by infusing leaves in water. Synonyms include “herbal tea” and “herbal infusion.”
Technically speaking, all teas are tisanes, but most tisanes are not teas.
In today’s culture, however, practically anything (except coffee and cocoa) that’s made by putting plant matter in water is called a tea. What’s my problem with that? It makes communication more difficult, less clear, and less terse.
- There is no other single word that means “a drink made with Camellia sinensis.” If we call everything tea, then we have to say “real tea” or “tea from the tea plant” or “Camellia sinensis tea” or something similarly ludicrous every time we want to refer specifically to tea rather than to all tisanes.
- There is a perfectly good word for “leaves infused in water.” There is no need to throw away “tisane” (or “herbal tea” or “infusion”) and replace it with a word that already has another meaning.
“But Gary,” I hear you cry, “people have been calling herbal infusions ‘tea’ for a long time!”
That’s true. I sometimes slip and call rooibos a tea myself. “Herbal infusion” is even an alternate definition of tea in the OED. I still maintain, however, that it makes clear, precise communication more difficult when trying to differentiate between tea (made from the Camellia sinensis plant) and drinks made from chamomile, honeybush, and willow bark.
Rooibos
Other words that go through this process are forced through it. Rooibos, for example, is the name for a specific tisane and the plant it’s made from (Aspalathus linearis). The word is Afrikaans for Red Bush. Despite the longtime use of the term in South Africa (the only place the rooibos plant grows), it was almost unknown in the United States in 1994 when Burke International of Texas registered “rooibos” as a trademark. This meant that in the United States, only Burke and its subsidiaries could use the common name of the plant. Had Burke not surrendered the trademark after starting to lose lawsuits, people would have been forced to come up with a new word.
Unfortunately, that wasn’t a decisive victory, as the South African Rooibos Council is being forced to repeat the process now with a French company.
As more people in the U.S. discover green rooibos, the name “red bush” becomes more confusing anyway. Rooibos, in my humble opinion, should remain the generic term here.
Oxidation vs. fermentation
There are other words in the tea industry that suffer from ambiguity and questionable correctness. You will find quite a bit of tea literature that refers to the oxidation of tea as “fermentation.” I had a bit of a row with Chris Kilham — The Medicine Hunter on Fox News — about this subject (it starts with “Coffee vs. Tea: Do your homework, Fox News” and continues with “Chris Kilham Responds“).
Fermentation and oxidation are closely related processes. That’s certainly true. But oxidation is the aerobic process that is used in the production of black and oolong tea, and fermentation is the anaerobic process that’s used in the production of pu-erh tea. Using the word “fermentation” to describe the processing of black tea may fit with a lot of (non-chemist) tea industry writers, but it makes it difficult to explain what real fermented tea is.
Precision matters
In chatting with friends, imprecise use of words doesn’t matter. If someone asks what kind of tea you want and you respond, “chamomile,” it’s perfectly clear what you want. But you’re an industry reporter, medical writer, or marketing copywriter, your job is to communicate unambiguously to your readers. Using the most correct terminology in the right way is a great way to do that.
Chris Kilham responds
Chris Kilham (left) and Dr. Manny from Fox News
A few days ago, I posted an admittedly rather snarky article on this blog entitled “Coffee vs. Tea: Do your homework, Fox News.” The main subject of the article was Chris Kilham, the “Medicine Hunter” from Fox News. Chris has responded to the article in email, expressing an interest in carrying on a dialog. Here is what he sent me (verbatim, and in its entirety):
Hi Gary- I saw your mistaken response to my segment on FOX, and thought I’d take time out to reply. Having studied coffee and tea deeply for decades, and having read thousands of pages of science on both, I stand by the claim that coffee is more potently antioxidant ounce per ounce. More Americans do drink black tea rather than green, the fermenting of tea does degrade the antioxidants, and no, the benefits of coffee are not limited to caffeine. I referred to the work of Astrid Nellig, who compiled over 300 human studies on coffee, not the others you noted. And yes, oxidation is in fact “rusting.” The exact same process occurs to cells that occurs to metal, though metal is not living tissue. I see you leave no place on your blog for intelligent feedback. Good idea. Before you rant off on a tangent, you really should get your science together. I have. Point by point I will be happy to go toe to toe. Enjoy.
First, Chris, I hope it was okay to use the thumbnail picture from your Medicine Hunter website. If you would prefer that I didn’t have it on my blog, let me know and I’ll remove it post haste.
Thank you for responding to my post. I appreciate getting feedback direct from the source, and I know you’re busy. Before going through your email point by point, I’d like to start by addressing the very last issue you raise: that there’s “no place on [my] blog for intelligent feedback.” As I said, I actively encourage intelligent feedback. There’s a place on every single blog post for people to leave their comments. If you’re looking at the front page of the site, it’s a link at the end of the post. If you’re looking at an individual article, it’s a section at the end with two tabs: one to see existing comments and one to leave your own. Please feel free to leave your comments on this or any other post on my blog, whether you agree with me or not.
Now, let’s — as you said — go point-by-point, toe-to-toe. I will quote your email, and then respond.
“Having studied coffee and tea deeply for decades, and having read thousands of pages of science on both, I stand by the claim that coffee is more potently antioxidant ounce per ounce.”
I did not dispute this. I said that I was unable to find meaningful studies regarding flavonoid content that covered multiple types of tea and coffee and various ways of preparing them, so I have no way of disproving your claim. What I did say is, “Flavonols aren’t the only basis for measuring the healthiness of a drink.” I will expand that to say that antioxidants in general aren’t the only things that make a drink healthy.
But if you can show me a study comparing antioxidants in coffee with antioxidants in black, green, white, oolong, purple, and pu-erh tea, I would love to see it. Really. I get that question a lot and I don’t have an answer for it.
“More Americans do drink black tea rather than green…”
I agree with you. In fact, I said “One accuracy point for Kilham” after I verified the claim with FAO’s statistics.
“…the fermenting of tea does degrade the antioxidants…”
Black tea is not fermented. This little piece of misinformation is a pet peeve of mine, and it’s one of the things that prompted me to write the original article. Black tea is oxidized. Fermentation is an anaerobic process. There are fermented teas (a favorite style of mine called shu pu-erh is both oxidized and fermented), but they represent such a miniscule percentage of the tea consumed in the United States that they don’t factor into this discussion. I will continue the discussion assuming you meant to say “oxidized” rather than “fermented.”
I am neither a chemist nor a nutritionist, so you’re going to have to tell me what “degrade” means in this context. You had originally said that they were “lost,” and I responded that “Flavonols aren’t ‘lost’ during oxidation; most (but not all) are converted into different antioxidants called theaflavins, and some convert to thearubigins (which produce the reddish hue of black tea).” Am I wrong?
“…and no, the benefits of coffee are not limited to caffeine.”
Did I say they are? No. I said, “But yes, coffee does contain antioxidants. So, in fact, does tea.” My reference to caffeine was specifically related to your claim that coffee can improve a bad mood. Every study that I found showed that you are absolutely correct. Coffee can improve a bad mood because of the caffeine, which means that tea and Mountain Dew can improve bad moods as well.
“I referred to the work of Astrid Nellig, who compiled over 300 human studies on coffee, not the others you noted.”
I am unfamiliar with Nellig’s work, but if the studies are specifically on coffee, they wouldn’t have pinged my radar (I am uninterested in coffee). If any of Nellig’s studies compare coffee with various types of tea, I’d like to read them, though.
“And yes, oxidation is in fact ‘rusting.'”
This could be an interesting discussion. When I was taking chemistry in school, I would have been smacked for saying that, for example, copper had rusted. Oxidizing was presented as the more general term. All rusting is oxidation, but not all oxidation is rusting. Perusing Merriam-Webster’s dictionary, however, I see that one of the definitions of rust as a verb is “to form rust: to oxidize.” And since the primary definition of oxidize is “to combine with oxygen,” I suppose the first part of your statement is true, based on current dictionary definitions. But do you really want to use “rust” as a synonym for “oxidize” in discussing living organisms? Try this:
Substituting “rust” for “oxidize,” a simplified description of the cardiovascular system would say that you inhale air into your lungs, where oxygen in the air is used to rust your red blood cells. Your arteries and capillaries carry those rusted blood cells to the rest of your body, where the red blood cells “un-rust” as they cause other cells in your body to rust. The de-rusted blood cells then return, via veins, to be rusted once again in the lungs.
Accurate, using those current Merriam-Webster definitions, but it sure sounds strange.
“The exact same process occurs to cells that occurs to metal, though metal is not living tissue.”
Really? To the best of my knowledge, metal is unable to use up oxygen and become un-rusted. Living cells can. It’s not the same process.
The “oxidation vs. rusting” discussion is largely semantic, though, and I don’t want this to turn into a massive debate about free radicals and properties of antioxidants. That wasn’t the point. The point was that your “Q&A With Dr. Manny” article went on a great length about health benefits of coffee without acknowledging that many (all?) of those benefits are shared with various types of tea. The only health benefits of tea that you brought up were antioxidants, and that’s only a single piece of the puzzle.
“Before you rant off on a tangent, you really should get your science together. I have.”
Okay, if you want to call my post a “rant,” I’ll have to agree. It was. But it was by no means “off on a tangent.” It directly addressed your Fox News story, directly on-point. It wasn’t off-topic. And I haven’t seen you call out one single scientific error in what I said (unless you want to call my bullheaded prescriptivism on the definition of “rust” a scientific error).
Coffee vs. Tea: Do your homework, Fox News
Oh, look! A flavonol! This stuff must be really, really healthy!
Last Friday, Fox News ran a “Q&A with Dr. Manny” segment to address the question, “Coffee vs. Tea: Which is Healthier?” Dr. Manny Alvarez handed the question off to someone named Chris Kilham, who I assumed was a scientist or another doctor. I was wrong, but we’ll get to that later.
Kilham began with some general statements (e.g., “For centuries, coffee has been praised for its invigorating properties. And it is truly healthy for you.”) and then stated his opinion: “For the most part, coffee is healthier for you.” Wow. That took me by surprise. Let’s continue and see what kind of well-researched and scientifically-backed justification he puts forth to back that conclusion.
The very next sentence is “The majority of people who drink tea, drink it black, and there’s no question that naturally occurring compounds in coffee are exceptionally good for you.” Really? I’m not sure what the first half of that sentence has to do with the second half, but let’s look at the first half.
I’m going to assume that he meant “most tea drinkers drink black tea” as opposed to “most tea drinkers don’t add milk or cream.” If he’s speaking of the United States, then the Tea Association of the USA backs him up. Their Tea Fact Sheet says that 80% of the tea consumed in the U.S. in 2010 was black tea. Worldwide, statistics vary. Teavana, for example, in the “Types of Tea” section of its website, says that “Green tea is the most popular type of tea, mainly because it is the beverage of choice in Asia.” The Food and Agriculture Organization of the United Nations (FAO) disagrees, however, stating that projected 2010 tea production was 2,443,000 tonnes of black tea vs. 900,000 tonnes of green tea. No offense, Teavana, but I think I’ll go with FAO’s numbers on this one. One accuracy point for Kilham.
Next, he proceeds to say that, “Two large cups of coffee, or 300 milligrams of caffeine per day, can improve a negative mood.” Assuming he’s referring to studies like Rogers & Dernoncourt, Haskell et al, or Peeling & Dawson, it’s the caffeine that has the effect, not the coffee per se. So it not only applies equally to coffee and tea, but you could get the same effect from swilling a two-liter of Mountain Dew.
“Rusting of cells in our bodies? Rusting? And they quoted this guy as an expert?”
His next claim starts with, “Research into the chemical properties of coffee show that a cup of Joe contains potent, protective antioxidants, which inhibit the rusting of cells in our bodies.”Whoa! Back up here. “Rusting of cells in our bodies?” Rusting? And they quoted this guy as an expert? Metal rusts. Cells don’t. Oxygen is the basic fuel that keeps our cells going. Our entire cardiovascular system exists to get oxygen to our cells. *sigh*
But yes, coffee does contain antioxidants. So, in fact, does tea. He proceeds to tell us, “Coffee is especially high in one group of antioxidants, flavonoids.” I attempted to find out whether coffee or tea contains more flavonoids, but there are just too many variables. Suffice it to say they both have plenty.
“And this next paragraph is where Kilham really shows his ignorance about tea.”
And this next paragraph is where Kilham really shows his ignorance about tea: “But if you’re drinking green tea, which is simply tea that hasn’t been fermented, then I would probably have to say that green tea is the healthier drink. It’s rich in flavenols [sic], which are lost when the tea is fermented.” Where do I even start with this?
- First of all, green tea isn’t simply “tea that hasn’t been fermented.” Black tea hasn’t been fermented, either. Nor have white tea and oolong tea. Either Kilham doesn’t know the difference between fermentation and oxidation, or he doesn’t know the difference between black tea (which is oxidized) and pu-erh tea (which is fermented). I’m guessing both, and I’ll henceforth assume he means oxidized whenever he says fermented.
- Next, it’s “flavonols,” not “flavenols.” If you’re going to babble pseudoscience, at least spell the words right.
- Flavonols aren’t “lost” during oxidation; most (but not all) are converted into different antioxidants called theaflavins, and some convert to thearubigins (which produce the reddish hue of black tea).
- Flavonols aren’t the only basis for measuring the healthiness of a drink. Focusing on them to the exclusion of everything else shows that Kilham just didn’t bother to do any research on tea.
He finishes his answer with the standard platitude of the underinformed: “The bottom line: If you’re talking about coffee and black tea, coffee is the healthier choice. If you’re a green tea drinker, green tea is the healthier choice.”
What’s wrong with that conclusion? It oversimplifies the issue and ignores all of the tea styles other than green and black. It doesn’t look at different types of black tea (or variants like the new purple tea from Kenya) or different ways of preparing them.
When I first wrote this response (before Firefox crashed and killed it), I didn’t know who Chris Kilham was. As I mentioned earlier, I assumed he was a medical doctor, researcher, or scientist. When I went to his website, however, I found that he’s a “medicine hunter, author and educator” who “travels the world in search of traditional, plant-based medicines, and works with shamans, healers, growers, harvesters, scientists, trade officials and other plant medicine experts in dozens of countries.” Yep, when I want accurate scientific health information, I go to shamans and healers.
There’s a quote from Dr. Alvarez that says, “I love adventure! That’s why I love teaming up with The Medicine Hunter, Chris Kilham.” Very telling. Alvarez didn’t call Kilham because he loves accurate information or well-researched responses. He called him because he loves adventure! Of course.
I think I’ll have another cup of tea and improve my mood.
I am a 
Tea With Gary 