Biomarkers of Dietary Patterns: A Systematic Review of Randomised Controlled Trials
Abstract Objectives We undertook a systematic review of clinical trials to identify a) dietary biomarkers being used to assess dietary pattern compliance, and b) novel biomarkers that are affected by intake of distinct dietary patterns. Methods The search strategy was developed in Medline and adapted for four additional databases: EMBASE, Cochrane CENTRAL, PreMedline, and CINAHL. Two independent reviewers extracted data and assessed risk of bias using the Cochrane tool. Results Literature search retrieved 3930 records; 450 full texts were assessed, and 30 articles reporting randomised controlled trials met the inclusion criteria. The most studied dietary patterns were the Mediterranean diet, healthy Nordic diet, Dietary Approaches to Stop Hypertension (DASH) diet, followed by low glycaemic-load diet, vegetarian diet, diets based on national and international guidelines (i.e., United Kingdom and World Health Organization Eating Guidelines), Korean diet and prudent diet. Of these, 13 articles incorporated prospectively identified dietary biomarkers, the most common being omega-3 index from erythrocytes or whole blood, 24-h urinary electrolytes, and serum or plasma carotenoids. Seventeen articles identified novel metabolomic biomarkers associated with dietary patterns, the most frequently identified being those associated with protein, lipid, and fish intakes. Conclusions Using dietary biomarkers of single nutrients, individual foods and food groups is commonly used to assess dietary compliance to dietary pattern interventions in controlled settings. However, identifying an individual's specific or broad dietary pattern, based on their biomarker profile, remains an area for future research. A framework that incorporates multiple biomarkers of individual dietary characteristics is likely necessary to accurately capture the complexity of dietary patterns. Funding Sources N/A.