Healthy subjects who received daily caffeine-free green tea extract capsules had an increased production of detoxification enzymes, which may provide some cancer-fighting benefits, study findings show.
"Concentrated green tea extract could be beneficial to those who are deficient in the detoxification enzyme and shouldn't be harmful for those who have adequate detoxification enzyme," lead investigator Dr. H.-H. Sherry Chow, of the University of Arizona, Tucson, told Reuters Health.
Boneheaded. Let me tell you why. First, we already went over how green tea supplements are actual pro-oxidants not anti-oxidants. So what's going on with the Rueters statement? If you look at the study ($ requrired), what they found was if they have a supplement of polyphenon E (containing 800 mg EGCG), the participants had increased production of an enzyme called GST that helps to detoxicify your liver and thus your body (that's really broad and general, and I actually hate the word detoxicify but we'll stick with it). The thing is, Why would your body ramp up production of detoxifying enzyme. Maybe because it's under toxic attack? Why yes! Specifically, GSTs are induced by oxidative stress in the liver, which is exactly what we know EGCGs do. So the GST pool is higher because the stress is higher; when the stress goes down, the GST does too. So we really don't know whether the GST reserve is any better or not. So does this sound like a good thing for your body to go through? No.
Simply put, the authors' conclusions are the equivalent of stepping outside your house and seeing military troops all over the place, armed to the teeth and coming to the conclusion, "My what a peacefull day, look at all the protectors around". They're there for a reason, and that reason isn't likely to be good.
Hat tip to reader Tim for sending this in.
Update 22 Aug, 8:08 PM -- Snapple may want to rethink this approach. Hey, your liver may necros but your karma will be in good shape! Hat Tip to Jon W.
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I just discovered your blog and it's just the kind of thing I've been looking for. So many products are released without being properly tested. Are these scientists being paid to produce "good" results? Or what is going on here?
Fight cancer by attacking your liver!! :-)
Thanks for this item ... it's both useful and instructive.
Another reason to avoid weak tea.
So here's my question: Is there ACTUALLY any data out there suggesting that green tea use can reduce cancer rates or otherwise produce a healthier individual?? I know there's some data suggesting thermogenic properties which facilitate weightloss(?)...but that's another story.
Anyway, IFF green tea reduced cancer rates, via a mechanism which involved raising your GST levels (i.e. its toxic, your body adapts), would this really be a bad thing? Think of it as 'priming' your body for an immune/antioxidant response, perhaps?
Reason being, if it were bad for you, would we not (expect to?) see a rise in longer-term health problems amoung green tea users (maybe it's too recent a fad..)?? Also, if EGCG is the root cause, doesn't this same toxicity likely occur in grapefruit juice, for example? I realize grapefruit juice does interfer with certain medications, is it b/c it slows up your body's naturally disposal pathways for byproducts of those drugs?
On a side note, I was at a recent conference on microbiology, and noted at least 2 posters about green tea having what we'd call 'anti-microbial' properties, i.e. extracts kill some bacteria under some conditions.....wish I'd read it more closely. It does make sense in light of the oxidative stress you're discussing.
Sorry for the 1000 questiosn, but this is a really interesting topic! Any thoughts would be appreciated.
PBC.
PBC, So there are some studies but those on supplements haven't shown any benefit (that I know of. If you know of a solid one, gentle reader, please post it).
If they did reduce cancer it would be a cost benefit analysis at that point. My guess is that it would come out on the wrong side since the liver tox would probably show up long before you would expect to see a benefit (the ingestion would have to be long term). Additionally, I'm not sure how cancer made it in to the researchers mind. 1) like I mentioned the GST reserve is probably not increased and 2) GSH conjugation may or may not prevent cancer anyway and 3) it would only work to prevent an environmentally caused one anyway.
I wouldn't expect to see a problem with green tea drinkers. The amounts are so vastly different that a tea drinker (even at a rather excessive amount), wouldn't have these drastic liver effects. This is the whole problem with extracts, and "essences",...etc. You've concentrated everything (poppy -> opium; foxglove -> digitalis), and that changes everything.
Grapefruit juice is a whole different ball game and here's where it gets really interesting (this is a favorite topic of mine). If you give OJ there is a anti-oxidant effect on the blood stream. If you give a load of Vitamin C, it does nothing. So there is something going on with intact fruits/juices that we clearly don't understand. Read more about this here:
http://scienceblogs.com/angrytoxicologist/2007/05/orange_juice_or_vitam…
Snapple's take on EGCG...
Regarding green tea and cancer (I admit to using Pubmed, where us biologically inclined students get info most of the time), I searched "green tea, cancer" and got 985 pprs, 216 reviews. Many of them on EGCG, and the one from the media release came up. Many of them make reference to tumor inhibition in animal models, which isn't inconsistent with toxicity, as you alluded to in your first post on this topic (if I recall). I've had the mental association between 'green tea" and 'anti-cancer' purely from the media-hype for a long time, and there appear to be some papers of real research out there. I think the important thing might be that there's a difference between chemo-therapy and preventative dieting, or at least there should be. I wouldn't want a methotrexate pill in my lunchbox b/c it happens to kill cancer when I actually have it...
Regarding green tea and diets, it might be more about the media/diet-industry advertising machine influencing my impressions than any real data. Men's health might be the culprit publication...they're good at half-assing science reports. As a long time weight-lifter/athlete, I've also seen a lot of diet supplements that included green-tea extract (I avoid them). Pub-med: 11 papers, and the ones i looked at the abstracts for show NO-difference (double-blind) vs. placebo., unless exercise is involved (Eur J Med Res. 2006 Aug 30;11(8):343-50.) But lots of groups are asking questions, so somehow the rumor got out there. You're right though, definitely a lack of hard evidence. Glad I took the time to research that :-)
Thanks for the orange-juice post! I'm going to go read that now...
Thanks also for addressing my questions. I've been reading your blog for a month or two now (since it was linked from pharyngula), and really enjoy it!
PBC.
Gentile reader? But what if I'm Jewish?
We're generally epidemiologically trained to distrust studies that use intermediate markers as outcomes of experiments. What I mean here is that something that can be tested for in the blood (for instance an inflammatory marker) is not a disease outcome. Levels of some substance going up or going down can be interpreted as good or bad for your health. This study seems like a classic example. Angrytox interprets this as bad and the authors of the study interpret it as good.
That's why I would rather see studies that tie treatments like this to actual disease states -in this case less cancer (good) or more liver disease (bad). Better yet we would like to see a study that tells us what the effects on mortality are like. This is because both effects might be opertaing at the same time (i.e. less cancer and more liver disease)- so what's the tradeoff across all diseases? A treatment could be simultaeously decreasing cancer and increasing liver disease resulting in a net effect of no lives saved (or worse).
So this study doesn't really say that green tea extract is actually a good or a bad thing to take.
There goes my spelling getting me into trouble again. Gentle. Thanks, Nat.
Very good points. While this study doesn't show that green tea supplements would be bad, other studies do (see the first edition post using the link in the post above "pro-oxidant" especially the review article that I reference in that post). You're correct in noting that this study has a end point is really vague. What does increased GST mean? Who knows? What's clear is that the authors really overstepped what the study showed and ignored what previous studies have shown.
Mortality studies would be great but they are just to big and full of confounders to do with something like green tea (or almost any diet attribute for that matter).
I've skimmed the paper in Chemical Research and Toxicology (yes, I'm coming to the party late - I blame the day job). I'm going back through in detail, and looking at references, but it's enough for me to form an opinion that we're dismissing green tea extract a little too quickly. The mechanisms may be debatable, but the authors didn't appear to dispute the evidence that polyphenols have disease-preventing activities. They've brought up a number of legitimate concerns about safety at high doses. That's good because a lot of people just aren't going to be sensible about supplements. However, while I'm still doing my reading on the subject, right now I'm coming up with a different risk characterization from what you've presented.
For the record, I use GTE for the purpose of increasing energy expenditure while I'm in the final 10 pounds of a multi-year, 60 pound weight loss program; the doses I'm taking are much lower than those discussed in Lambert et al's paper, and it reduces reliance on caffeine for the same purpose.
Thanks for blogging about this, and for encouraging me to look into this further.
I just drink green tea because it tastes good, if there are any health benefits then that is an add-on. Most supplements don't offer any additional benefits in their concentrated form anyhow. My favorite online loose tea shop: http://www.tealaden.com has posted several health studies on tea but I still will enjoy my Lung Ching Dragonwell even if there were no benefits other than taste.
Once again blog science reporting outshines mass media... Thanks for this.
Fortunately, I only drink green tea because it's delicious. Same goes for eating garlic - people who buy those flavorless garlic supplements need to re-examine their lives, I'm thinking.
The Ohsaki study did show that green tea drinkers in Japan had more positive cardiovascular outcomes, especially in women, though there was no connection to cancer seen in this study. Obviously drinking green tea and taking a supplement are two different things, but how many consumers really think about that?
Good comments all around. Thanks!
As far as I can tell all the positive outcomes are from tea studies, not supplements. If anyone has one to contradict this, please post a link (really, supplement info is a nerd hobby of mine).
JLowe: While I don't think the risk is dire, what I do find outrageous is that something being touted as a health booster, if anything, is the opposite. Perhaps I didn't stress the latter over the former, enough.
Sci_Libby, RE: "How many consumers think about that?"
Well, hopefully a few more now!
-AT (drinking tea right now)
I love green tea. Drink Arizona Green Tea.
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Good comments all around. Thanks!
As far as I can tell all the positive outcomes are from tea studies, not supplements. If anyone has one to contradict this, please post a link (really, supplement info is a nerd hobby of mine).
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As far as I can tell all the positive outcomes are from tea studies, not supplements. If anyone has one to contradict this, please post a link (really, supplement info is a nerd hobby of mine).
JLowe: While I don't think the risk is dire, what I do find outrageous is that something being touted as a health booster, if anything, is the opposite. Perhaps I didn't stress the latter over the former, enough.
Sci_Libby, RE: "How many consumers think about that?"
Well, hopefully a few more now!
-AT (drinking tea right now)
Good comments all around. Thanks!
As far as I can tell all the positive outcomes are from tea studies, not supplements. If anyone has one to contradict this, please post a link (really, supplement info is a nerd hobby of mine).
I love drinking healthy thinks and of course green tea is my favorite drink. Thanks
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Good comments all around. Thanks!
As far as I can tell all the positive outcomes are from tea studies, not supplements. If anyone has one to contradict this, please post a link (really, supplement info is a nerd hobby of mine).
It seems to me God is doing small (and big) miracles every day in Haiti as the recovery effort continues. why not these as well? praying with you.
Good comments all around. Thanks!
As far as I can tell all the positive outcomes are from tea studies, not supplements. If anyone has one to contradict this, please post a link
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As far as I can tell all the positive outcomes are from tea studies, not supplements. If anyone has one to contradict this, please post a link (really, supplement info is a nerd hobby of mine).
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