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May 20, 2005


I don't think the information at the URL you cite will meet many scientists standard of proof. Read the opening sentence carefully again:

"Green tea appears to protect against cancer by affecting a “promiscuous” protein"

The researchers who did the work aren't claiming it's proof; why are you? All that the researchers have found is that some extract of green tea binds some protein.

The study doesn't prove that:

1. this particular extract of green tea survives passage through the digestive system and reaches the bloodstream;

2. this particular extract of green tea reduces cancer risk;

3. that green tea has any effect at all on cancer.

The study quoted is not the worst I've seen; there no evidence of a conflict of interest, and the work is published in a real journal (Biochemistry). However, note what the study is not:
it is not a long-term, double-blind study comparing a placebo to green tea in two groups of patients who are matched for age, lifestyle and income. That is the only kind of study which can determine the efficacy and safety of a new therapy.

To learn more about the diversity of opinion on this or any other medical topic, do what real researchers do: look at PubMed: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi

I'm sure that a search for "green tea" or "antioxidants cancer" will turn up a huge list of citations. You may be surprised at how much of them you can understand if you're willing to ignore a few words you don't understand (works for me anyway).

Thanks, Alison - your scientific training helps a gullible humanities major like me sort out the facts. I thought the press release was talking about "proof." Your elucidation points out where I didn't read carefully or think through the implications of the press release.

This looks like an "oops". I'll let the post and comments stand, that others may be educated, as I have been, by your remarks.

Sorry if it seems like I lectured you. "Proof" is one of the words that pushes my buttons. The main point is to maintain a healthy scepticism about published research results. A lot of them are just plain wrong, but the ones that are kind of muddled are often worse.

No, I didn't feel lectured, don't worry. I was never trained to review scientific research; you were. Yes I know that one shouldn't believe everything one reads, and I try to apply critical thinking skills to new information, but the term "research study" and the imprint of a university medical school were enough in this case to make me suspend all disbelief. I needed the correction.

Back to the subject of green tea - in my situation I come across many recommendations about what to eat and what to avoid in order to prevent recurrence of cancer. (Since my diet was pretty healthy before, eating plenty of fruits and vegetables, for instance, didn't prevent the original onset of breast cancer.) I've had to pick and choose what things I was going to do and not do. I eat some organic produce and buy hormone-free meats and poultry. I'm not doctrinaire about these things.

Drinking green tea once a day won't harm me. Adding it to my diet could only benefit, or at the least, cause no adverse effect. So I will probably continue to drink green tea when I think of it (I don't like it as much as black tea!), largely because of this idea floating around that it fights cancer. Is the research strong enough? I don't know, but because it's cheap, easy, and has no deleterious effects, I'll do it.

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