Does coffee or tea prevent brain tumours?

A cup of coffee or tea a day can help protect you against brain tumours, according to recent media reports.The reports follow a study published in the American Journal of Clinical Nutrition in October 2010, which found that a daily cup of coffee or tea can stop brain tumours growing by restricting blood flow to the brain.

However, leading UK neuro-oncologist Roy Rampling, has warned that the study does not give us a clear reason to drink more or less coffee or tea.

The study, quoted in NHS Choices, was conducted by researchers from Imperial College in London and other academic institutions in Europe and the US. It involved 410 000 men and women aged between 25 and 70 from across ten European countries over a period of 8.5 years.

Researchers found that people who drank more than 100ml of coffee or tea per day seemed to have a 34% lower risk of being diagnosed with a glioma.

However, Professor Rampling, who interpreted the results for Brain Tumour UK, says: “This study and a previous paper quoted in the study do not give us a clear reason to change the way we behave with respect to tea or coffee." 

He adds that the risk of developing a brain tumour remains small independent of diet. 

“Many of us already take at least 100ml of coffee or tea per day and taking large amounts (more than five cups) may have other health drawbacks.”

However, Professor Rampling says the papers are of considerable scientific interest.

“Any inhibitory effect on brain tumour development by antioxidant/caffeine containing beverages needs to be confirmed. If confirmed then the mechanism of inhibition needs to be clarified and possibly exploited. In the meantime changes of beverage consumption to modify the risk of developing a brain tumour do not seem justified,” he says.

Professor Rampling’s full report follows below.

The effect of coffee and tea consumption on glioma development

The paper by Michaud et al (1) “Coffee and tea intake and risk of brain tumors in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort study” is a substantial piece of work by a reputable group.

They have specifically examined the relationship between the incidence of 2 broad types of brain tumour (glioma and meningioma) and the daily intake of coffee and tea.

Their conclusion is that taking relatively small amounts of tea or coffee (>100mL) helps to protect against developing a glioma. However they do not show that the more coffee or tea you drink, the lower the risk and they do not claim any effect at all on meningiomas.

They reference another recent study by Holick et al (2) that has shown a similar inverse correlation between coffee consumption and risk of glioma in both men and women.

However in this paper the risk reduction for developing a glioma is for people taking more than 5 cups of coffee per day.

Both papers discuss previous work in this field, some of which appears to support their conclusions but other of which fails to show any relationship of glioma incidence with coffee drinking.

Further confusion arises in that some papers show a different effect between the sexes and some that show an effect for coffee but not tea and a variable association when caffeine is examined independently of its nutritional source. Both papers acknowledge the difficulty of producing consistent results in this type of work.

Why might coffee and tea protect against the development of glioma? Firstly, both beverages contain large amounts of polyphenols and flavonoids, that have strong antioxidant activity and are thought to inhibit tumour promotion and possibly protect against cancer. Coffee and tea also contain caffeine. Testing caffeine in the laboratory however gives inconsistent results, sometimes increasing and sometimes inhibiting the development of malignant cells. Caffeine also alters blood flow to the brain, which might influence tumour progression.

How then do we interpret these results and what do we need to do? Clearly there is no suggestion in any of these studies that drinking tea or coffee increases the risk of glioma and indeed there is a possibility that drinking either of these beverages over the long term may protect in some way.

However it must be remembered that some previous studies have shown no protective effect. Also there is a discrepancy between these two studies with one saying that a large coffee intake is needed (>5 cups per day) whilst the other says that any amount over 100ml (one small cup) is beneficial.

Also it is possible that it is not the coffee at all but some other characteristic of people who drink more coffee that is protective. Neither study addresses the influence of coffee or tea when a person already has a brain tumour.

In summary, neither of these papers gives us a clear reason to change the way we behave with respect to coffee or tea.

The risk of developing a brain tumour remains small independent of diet. Many of us already take at least 100ml of coffee or tea per day and taking large amounts (>5 cups) may have other health drawbacks. The papers are however of considerable scientific interest.

Any inhibitory effect on brain tumour development by antioxidant/caffeine containing beverages needs to be confirmed. If confirmed then the mechanism of inhibition needs to be clarified and possibly exploited. In the meantime changes of beverage consumption to modify the risk of developing a brain tumour do not seem justified.

1. Coffee and tea intake and risk of brain tumors in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort study Michaud et al Am J Clin Nutr 2010; 92:1145–50 2010.

2. Coffee, Tea, Caffeine Intake, and Risk of Adult Glioma in Three Prospective Cohort Studies Crystal N. Holick1, Cancer Epidemiol Biomarkers Prev; 19(1) January 2010 p40