Table 1.

Categorisation of types of participants, interventions, comparators, outcomes and study types

Data domain	Categories used for data extraction
Participants	• pregnant women • mothers and infant pairs • infants • children of preschool-aged children • school-aged children • adults • elderly • postmenopausal women • participants with a condition(s) or not
Interventions	• foods (e.g. whole foods, food products, complete diets or dietary patterns, specially formulated foods, complete nutritional formulas, breastfeeding) • supplementation/supplements (e.g. single or multiple nutrients, bioactive non-nutrients, plant components) • combined food and supplementation/supplements • nutrition education, counselling and coordination of care • policies, programmes or systems that influence nutrition-related or nutrition-sensitive outcomes • other, if no component of the intervention could be categorised as any of the above
Comparator	• placebo • no intervention • usual care • different intervention • other
Outcomes	• mortality • clinical or nutritional status assessments (e.g. anthropometry, clinical and biochemical measurements) • frequency and/or severity of disease • diet quality and/or variety • food/nutrient/dietary intake • diet-related behaviours (including eating behaviour) • other non-diet-related behaviours • withdrawal from the study, drop-out or adherence-related • adverse events, side-effects and/or safety • cost-effectiveness or economic • quality of life • other
Study designs	• randomised controlled trials (including parallel or cross-over design); • experimental non-randomised studies (non-randomised controlled trials, controlled before-after studies, interrupted time series and repeated measures studies) • observational studies (cohort, case-control, cross-sectional)