Higher coffee intake may be linked to lower risk of prostate cancer

Drinking several cups of coffee every day may be related to a lower risk of developing prostate cancer, suggests an analysis of pooled data from the available evidence, published in the online newspaper BMJ Open.

Each additional daily cup of the drink was associated with a reduction in relative risk of almost 1%, the results indicate.

Prostate cancer is the second most common cancer and the sixth leading cause of cancer death in men. Almost three out of four cases occur in the developed world and, since the 1970s, new cases of the disease have increased dramatically in Asian countries, including Japan, Singapore and China.

Coffee consumption has been linked to a lower relative risk of liver, bowel and breast cancer, but so far there is no conclusive evidence of its potential role in reducing the risk of prostate cancer.

In an attempt to advance the understanding of the problem, the researchers sifted through research databases in search of relevant cohort studies published until September 2020.

They gathered the 16:15 data reported on the risk of prostate cancer associated with higher coffee consumption, compared to the lowest; 13 reported the risk associated with an additional daily cup. The highest level of consumption ranged from 2 to 9 or more cups per day; the lowest level ranged from none to less than 2 cups a day.

The included studies were carried out in North America (7), Europe (7) and Japan (2). They included more than 1 million men (1,081, 586) of whom 57,732 developed prostate cancer.

In comparison to the lowest category of coffee consumption, the highest category was associated with a 9% reduction in the risk of prostate cancer. And each additional daily cup was associated with a 1% reduction in risk.

Further refining the analysis for localized and advanced prostate cancer, it showed that, compared to the lower intake, the higher intake was associated with a 7% lower risk of localized prostate cancer and a 12% -16% lower risk of advanced and fatal prostate cancer, respectively.

The researchers recognize that, due to the observational design of the included cohort studies, factors not measured or uncontrolled in the original studies may have distorted the combined risk estimate.

The amount of coffee drunk may also have been classified incorrectly, as it depended on collection. And the type of coffee and methods of preparation varied between studies. The design and methods of the included studies also varied, so caution is needed in interpreting the results, they say.

However, there are plausible biological explanations for their findings, they point out.

Coffee improves glucose metabolism, has anti-inflammatory and antioxidant effects and affects sex hormone levels, factors that can influence the onset, development and progression of prostate cancer, they point out.

And they conclude: “This study suggests that increased coffee consumption may be associated with a reduced risk of prostate cancer. Additional research is still needed to explore the underlying mechanisms and active compounds in coffee.

“If the association is proven to be a causal effect, men can be encouraged to increase their coffee consumption to potentially decrease their risk of prostate cancer.”