Coffee and cancer risk, epidemiological evidence, and molecular mechanisms

Abstract

Although early studies suggested that coffee consumption might increase risk of some cancers, more comprehensive epidemiological and experimental data now generally indicate either neutral or beneficial effects. In this review, we summarize the current evidence for associations between breast, prostate, colorectal, and liver cancers and the consumption of coffee, and discuss the experimental evidence for potential chemopreventive mechanisms of coffee and coffee constituents. The epidemiological evidence consistently indicates that coffee protects against liver cancer, and also point toward protective effects for risk of colorectal cancers (with relative risks of 0.50 (95% CI: 0.42-0.59) and 0.83 (95% CI: 0.75-0.92), respectively, in the most recent meta-analyses). There seems to be no association between the overall risk of breast and prostate cancer and coffee intake. However, for subgroups such as postmenopausal breast cancers, advanced prostate cancers, and breast and prostate cancer survivors, an inverse association with coffee intake is indicated. Potential mechanisms for chemopreventive effects of coffee phytochemicals includes inhibition of oxidative stress and oxidative damage, regulation of DNA repair, phase II enzymatic activity, apoptosis, inflammation, as well as having antiproliferative, antiangiogenetic effects and antimetastatic effects. The experimental evidence for effects of coffee and coffee constituents on each of these processes is discussed.

Coffee reduces KRAS expression in Caco-2 human colon carcinoma cells via regulation of miRNAs

“…Previous epidemiological studies indicated that coffee consumption is associated with a protective effect for colorectal cancer with a relative risk of 0.83 (95% confidence interval: 0.75-0.92) in a previous meta-analysis (27,28). The inhibitory effect of coffee extract on KRAS expression may be a key factor underlying the protective effects of coffee against colorectal cancer.…”

Green and roasted coffee extracts as antioxidants in βTC3 cells with induced oxidative stress and lipid accumulation inhibitors in 3T3L1 cells, and their bioactivity in rats fed high fat diet

“…Studies revealed that all coffee extracts decreased ROS generation by 28.6-61.0% compared to the control and by 59.1-77.8% compared to cells with induced oxidative stress. The results suggest that coffee extracts decreased the level of ROS even in cells representing physiological amounts of ROS due to their high scavenging and oxidative stress inhibition activities [34,35]. The higher activity to decrease ROS generation showed DiRCE.…”

“…The extract of roasted coffee, particularly the fraction containing monochlorogenic acids and more polar MRP, caused an increase of antioxidant potential evaluated as high radical-scavenging capacity and a high level of hydrophilic antioxidants in rat serum and may be potentially used as a nutraceutical of anticarcinogenic properties due to inhibition of oxidative stress resulting from the antioxidant capacity [34]. The results related to the antidiabetic activity of coffee, including protection against oxidative stress of β cells and the low levels of triglycerides, glucose and oxidized glutathione levels in rats, showed a beneficial effect of non-fractionated GCE.…”

The role of diet in cancer: the epidemiologic link

“…chlorogenic acid, polyphenols and their metabolites). 47 Coffee constituents may have antioxidant properties, play a role in the regulation of DNA repair, apoptosis and inflammation, 47 have effects on hormonal activity, [48][49][50] glucose tolerance 51 and circulating levels of immune and inflammatory markers. 52 …”