Randomized controlled trials investigating the relationship between dietary pattern and high-sensitivity C-reactive protein: a systematic review

Abstract

Context: Elevated serum concentration of high-sensitivity C-reactive protein (hsCRP), a biomarker of systemic inflammation, is associated with increased risk for coronary heart disease (CHD) and cardiovascular events (CVEs). Because elevations in hsCRP often occur in parallel with elevations in low-density lipoproteins (LDLs) and both biomarkers are reduced by hydroxymethylglutaryl-CoA reductase inhibitors (ie, statin drugs), efforts to determine nonpharmacological treatments to lower hsCRP remain limited. Dietary modifications in particular are rarely discussed as viable clinical interventions yet merit investigation.

Objective: This systematic review was performed to assess the relationship between dietary patterns and hsCRP among individuals enrolled in randomized controlled trials.

Data sources: National Library of Medicine (ie, MEDLINE) and Google Scholar searches were performed using the search terms "C-reactive protein," "CRP," "dietary pattern," and/or "diet" to identify articles published between January 2000 and October 2017.

Data extraction: Data were extracted and analyzed according to PRISMA guidelines. Identified abstracts were reviewed and cross-referenced for relevance to dietary pattern. Full-text manuscripts were then abstracted for their principal findings. Fifty-six manuscripts met inclusion criteria for detailed review.

Results: Clinical trials of dietary interventions to reduce hsCRP are mixed in quality and findings. Several specific dietary patterns may reduce hsCRP, including low-fat, low-carbohydrate, Mediterranean, Portfolio, Paleolithic, and the Dietary Approaches to Stop Hypertension (DASH) diets. However, results were mixed for the majority of dietary patterns (eg, low-glycemic load diets).

Conclusion: Information available to date suggests that a wide variety of dietary patterns may impact serum hsCRP, although studies are mixed in quality. The efficacy of dietary patterns for the treatment of elevated hsCRP as a strategy for primary prevention of CHD may be best elucidated in randomized clinical trials in healthy participants with elevated hsCRP but low or normal traditional risk factors, or by using more aggressive dietary modifications in high-risk patients. Given current incidence and prevalence of CHD risk factors, additional randomized controlled trials of this type are justified and needed.

Keywords: cardiovascular disease; dietary patterns; high-sensitivity C-reactive protein (hsCRP); inflammation; risk factors.