Researchers in Norway found that there is a lower risk of prostate cancer among men who drink boiled coffee. The study was published in the British Journal of Cancer. The lead author was Dr. Aage Tverdal who is with the Department of Pharmacoepidemiology at the Norwegian Institute of Public Health.

There have been conflicting reports and studies. A report published in 2007 by the World Cancer Research Fund/American Institute for Cancer Research says there is limited evidence linking coffee and prostate cancer. Ever since, studies have been showing contrasting results varying from no association to inverse associations between coffee and prostate cancer. A previous study examining boiled vs filtered coffee in relation to several cancer types revealed no result for prostate cancer.

However, there is strengthening evidence. Two diterpenes, cafestol and kahweol, are substances present in boiled coffee that have been found to demonstrate anti-carcinogenic activity. These substances can be trapped by coffee’s paper filter. This makes a difference in the coffee–prostate cancer relationship when considering boiled (non-filtered) coffee vs non boiled coffee

For the data, patient samples were obtained from the Norwegian cardiovascular screening program. The study involved 224,234 men aged between 20-69 years. All their coffee habits were documented from 1985 to 1999. From this sample, 5740 cases of incident prostate cancers were identified.

The results shows that for boiled coffee, compared to men who do not drink coffee, men who drink more than 1–4, 5–8 and 9+ cups per day of boiled coffee had hazard ratios of 0.84 (0.73–0.96), 0.80 (0.70–0.92) and 0.66 (0.55–0.80). For non-boiled coffee, the ratios were 0.89 (0.80–0.99), 0.91 (0.81–1.02) and 0.86 (0.74–1.00).

What’s a hazard ratio? A hazard ratio is the ratio of the hazard rates corresponding to the conditions described by two levels of an explanatory variable. For example, in a drug study, the treated population may die at twice the rate per unit time as the control population.

The conclusion: the findings suggest that there is a lower risk of prostate cancer among heavy drinkers of boiled coffee compared to drinkers of other types of coffee, with an inverse relationship between the number of cups per day and the risk of prostate cancer present only in men who drink boiled coffee.