TABLE 1.

PICOS inclusion and exclusion criteria

	Inclusion	Exclusion
Participants	•Adults aged ≥18 y •Healthy populations, including participants with obesity, risk factors for metabolic syndrome •No limit on the country in which the study was conducted	•Chronic health conditions affecting the gastrointestinal tract, metabolism, or dietary requirements
Intervention	•Feeding studies focusing on dietary patterns •Must evaluate overall diet quality or dietary patterns (e.g., Prudent, DASH, Mediterranean, unhealthy/Western diet) •Methodology papers of feeding studies	•Cohort studies •Observational/no intervention •Review papers •Conference abstracts •Single food/supplement-only interventions •Weight loss/calorie deficit (unless there was a weight-stable comparator or weight maintenance phase) •Postprandial interventions
Comparator	•Control usual diet (when measured) •Alternative feeding/dietary pattern, e.g., parallel or crossover study
Outcome	•Collection of biomarkers (e.g., serum, plasma or urine) investigating the influence of the feeding intervention on the metabolome •Collection of metabolites examined	•Studies investigating a single metabolite only •Studies measuring metabolites with respect to predicting/reflecting a disease outcome or risk factor
Setting	•Feeding study conducted in a laboratory where all or some intake is measured onsite in a controlled environment •Free living feeding study where foods are provided, and adherence is measured	•Laboratory-based feeding studies where single foods/meals are fed and postprandial responses measured

Abbreviations: DASH, Dietary Approaches to Stop Hypertension; PICOS, participant, intervention, comparator, outcome, and setting.