A storm in a green tea cup

The Guardian newspaper has excellent coverage of world and national events but science features surprisingly infrequently in its print edition.  Those of us who read the Guardian and are interested in science, therefore, have to treasure every crumb of science thrown our way.  A very small crumb was offered recently (Drinking green tea may help ward off Alzheimer’s, January 6th), in a short article based on a study performed at Newcastle University (a longer version appeared on the web site (http://www.guardian.co.uk/society/2011/jan/06/green-tea-alzheimers-cancer?INTCMP=SRCH).  I have to say that the very mention of green tea makes me sceptical as unsubstantiated reports of the health giving properties of this drink abound in the popular press.    So, what I do in the case of stories like this is to ask some simple questions.  The headline mentioned Alzheimer’s disease so I ask “did the researchers actually look at Alzheimer’s disease in humans?”   If they did examine Alzheimer’s disease I ask “how did they perform the study?”

I had a look at the original paper from the Newcastle group (http://www.ncbi.nlm.nih.gov/pubmed/21183323) and it turns out that, no they did not examine Alzheimer’s disease in humans, despite what the piece in the Guardian implied.  They set up a test system for the toxicity of some chemicals (Aβ peptides) thought to be important in human brain for the development of Alzheimer’s disease.  The test system consisted of rat neuronal cells in culture and the brain peptides were toxic to these cells.  Green tea extracts (subjected to a simulated gut digestion) reduced the toxicity of these Alzheimer-promoting peptides on the cultured cells. 

My conclusion would be that, based on this new study, there is indeed some effect of green tea extracts on the toxicity of Alzheimer-related peptides in a test tube system.  If I were the researchers I would worry that the effects they report of higher concentrations of green tea extract are less than the effects seen using lower concentrations; but let’s put that aside.  I don’t believe, however, that the work actually tells us anything about Alzheimer’s disease as it does not study the disease in humans.  To make any conclusion about the effect of green tea on Alzheimer’s disease, a large scale clinical trial with many patients (Alzheimer’s and controls) would be needed. 

So who put the Alzheimer’s slant on this study?  In their paper the researchers were cautious in their interpretation but the press release from Newcastle University contained the statement “Regularly drinking green tea could protect the brain against Alzheimer’s and other forms of dementia”.  This press release then formed the basis for most of the coverage in the media including the Guardian.  So it’s the university press office sexing up the findings that has lead to the unwarranted interpretation which has been picked up uncritically by the press.

In the end does any of this matter?  I believe it does.  These kinds of stories about the effects of food substances on disease are frequent in the popular press and they feature occasionally in the Guardian.   By reporting them in this way, the media do not giving a fair picture of the breadth and depth of work that is being done on human disease such as Alzheimer’s disease and which may lead eventually to new therapies.

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