Drinking more coffee may significantly reduce a person’s risk of prostate cancer, with a nearly 1% lesser likelihood seen with each additional daily cup of coffee consumed, an analysis of published studies suggests.
Coffee contains a number of biologically active molecules, the most well-known being caffeine. Theoretically, there are several biological mechanisms by which the various molecules in coffee could affect the development of cancer: coffee contains anti-inflammatory and antioxidant compounds, it can alter metabolism, and it can affect the levels of various hormones.
Prior research has shown that people who drink more coffee are less likely to develop certain types of cancer, such as liver, colon, and breast cancer. The relationship between coffee consumption and prostate cancer risk, however, has been unclear.
Researchers at Shengjing Hospital of China Medical University conducted a meta-analysis to better understand the association between coffee and this cancer’s risk. Meta-analysis is a type of study wherein scientists pool data from relevant, previously published studies. Since they include more data, meta-analyses have greater statistical power than any individual study.
Data included in this meta-analysis come from a total of 16 published studies. Of them, seven were conducted in North America, seven in Europe, and two in Japan.
The studies included data covering nearly 1.1 million people, of whom 57,732 developed prostate cancer. Coffee consumption in the studies was assessed using various self-reported questionnaires.
Analyses showed that, compared to those with the lowest daily coffee intake, those with the highest consumption had a roughly 9% lower risk of developing prostate cancer. Further analyses suggested that, for each additional cup of coffee consumed each day, the risk of prostate cancer decreased by nearly 1%.
“This study suggests that increased coffee consumption may be associated with a reduced risk of prostate cancer,” the researchers concluded.
Additional analyses showed that, compared to those with the lowest coffee intake, those with the highest intake had a 7% reduced risk of localized prostate cancer (cancer that is only in the prostate). The risk of advanced prostate cancer was reduced by 12%, and the risk of fatal prostate cancer by 16%.
Additional analyses that made statistical adjustments for possible confounding variables generally found consistent results.
The researchers noted that this study has limitations. Chief among them was the analysis’ use of observational data, making it difficult to conclude a cause-and-effect relationship from the data, since other, unmeasured factors could also be at play.
“For example, the inverse association between coffee consumption and prostate cancer could be attributed to risk factors related to coffee consumption, such as physical activity and healthy diet,” the researchers wrote.
They also noted that, since most of the included studies were conducted in North America and Europe — where both coffee intake and the incidence of prostate cancer are comparatively high — the findings may not be applicable to other parts of the world.
“Further research is still warranted to explore the underlying mechanisms and active compounds in coffee,” the researchers concluded. “If the association is further proved to be a causal effect, men might be encouraged to increase their coffee consumption to potentially decrease the risk of prostate cancer.”