Cancer
Coffee consumption and bladder, kidney and prostate cancers
Coffee and bladder cancer: inconclusive evidence
Although tobacco use and exposure to aromatic amines are the two main risk factors for bladder cancer, other lifestyle factors are also involved.
In 1990, the International Agency for Research on Cancer (IARC) considered that there was limited evidence available at that time that coffee drinking was carcinogenic to the human urinary bladder. It classified coffee in Group 2B (possibly carcinogenic to humans).
A number of studies since have reported a moderate increase in the risk of bladder cancer with coffee consumption9. However, the risk has not been associated with how much coffee has been consumed. or for how long, which suggests that any link between the two is not a straightforward one.
Recent evidence also contradicts these earlier findings: those who drink coffee are 18% less likely to develop bladder cancer than those who do not, and this figure increases to 26% in men9,11,21.
A recent, large literature review also suggests that coffee consumption could be linked to a reduced risk of bladder cancer, particularly in men5.
Therefore the evidence to date is inconclusive. A critical confounding factor is linked to the type of water used to prepare coffee, as chlorinated tap water is thought to increase the risk of bladder cancer, whereas mineral water does not appear to. Another confounder is smoking which usually goes hand in hand with both alcohol and coffee consumption21.
No association between coffee and kidney cancer
The World Cancer Research Fund (WCRF) identified a total of 23 studies, which all concluded there was no link between coffee consumption and kidney cancer11. A further review and another study including around 750,000 participants also found no link22,23.
Coffee consumption not linked to a higher risk of prostate cancer
In 2010, a meta-analysis of studies found no influence of coffee on the risk of developing prostate cancer24. Two further, large studies suggest that coffee drinkers are at lower risk of developing prostate cancer than non-coffee drinkers5, 25.
