Biomarkers of dietary patterns: a systematic review of randomized controlled trials

CONTEXT: Most methods for assessing dietary intake have considerable measurement error. Dietary biomarkers are objective tools for dietary assessment. Dietary biomarkers of dietary patterns have not been well described, despite modern dietary guidelines endorsing dietary patterns. OBJECTIVE: This systematic review sought to describe the dietary biomarkers commonly used to assess dietary patterns, and the novel biomarkers of dietary patterns identified by exploratory studies. DATA SOURCES: MEDLINE, Embase, Cochrane Central, PreMEDLINE, and CINAHL databases were searched. DATA EXTRACTION: Data extraction and bias assessment were undertaken in duplicate. DATA ANALYSIS: A qualitative approach was applied, without statistical analysis. CONCLUSION: In controlled settings, dietary biomarkers of single nutrients or of individual foods or food groups are commonly used to assess compliance with dietary patterns. However, currently, there are no dietary biomarkers or biomarker profiles that are able to identify the specific dietary pattern that has been consumed by an individual. Future work should seek to validate novel dietary biomarkers and biomarker profiles that are indicative of specific dietary patterns and their characteristics. A dietary biomarker panel consisting of multiple biomarkers is almost certainly necessary to capture the complexity of dietary patterns. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42019129839.