Coffee is one of the most widely consumed beverages globally. A substantial amount of observational data suggests an inverse relationship between coffee consumption and the risk for cardiovascular disease. The basis for this association is not clear. In this review, we specifically study the impact of coffee on inflammatory biomarkers as one potential mechanistic basis for this observation. Our objective was to systematically review randomized controlled trials that examined the effects of coffee consumption on selected cardiovascular biomarkers.
We systematically reviewed bibliographic databases including PubMed (NCBI), Embase (Elsevier), CINAHL (EBSCO), Web of Science (Clarivate Analytics), Cochrane Central Register of Controlled Trials (EBSCO), and CAB Abstracts (Clarivate Analytics). We searched for randomized controlled trials that studied the effect of drinking coffee on inflammatory markers of cardiovascular risk.
The search of electronic databases returned 1631 records. After removing duplicate records, and ineligible studies, we examined a total of 40 full-text documents, 17 of which were eligible for further analysis. In our review, boiled coffee, in particular, appeared to raise total and LDL cholesterol and apolipoprotein B, but evidence suggests no similar effect for filtered coffee. One study showed a significant increase in blood interleukin-6 levels among individuals who drank caffeinated coffee, compared to individuals consuming no coffee.
Based on our systematic review of randomized controlled studies, we cannot confidently conclude that an anti-inflammatory effect of coffee is a major contributing factor to the lower all-cause mortality reported in observational studies.