Mediterranean-type diets and inflammatory markers in patients with coronary heart disease: a systematic review and meta-analysis

The health benefits of a Mediterranean diet are thought to be mediated via its anti-inflammatory effects; however, the anti-inflammatory effect of this diet is unclear in patients who have already developed coronary heart disease (CHD). This systematic review and meta-analysis assessed the effect of Mediterranean-type diets on cytokines and adipokines in patients with CHD. An electronic search of the literature was conducted up to October 2016 using PubMed, Scopus, Web of Science, and Cochrane Library. Eleven of the 435 articles identified met eligibility criteria. Four observational studies reported significant inverse associations between Mediterranean-type diet scores and inflammatory cytokines. Five clinical trials (4 in non-Mediterranean countries) demonstrated nonsignificant reductions, and 2 trials conducted in Spain demonstrated significant reductions in C-reactive protein with a Mediterranean-type diet. Random effects meta-analysis of 4 controlled trials detected a nonsignificant difference in final mean value of C-reactive protein with Mediterranean-type diet vs low-fat diet. Despite promising findings from observational studies, this review demonstrated mostly nonsignificant effects of Mediterranean-type diet interventions on inflammatory cytokines and no effect in comparison to low-fat diets in controlled trials conducted primarily in Mediterranean populations. Therefore, randomized controlled trials of a traditional Mediterranean diet in non-Mediterranean populations and with multiple inflammatory biomarkers are needed in the high-risk CHD patient group.