Table 1

PICOS categories in diet and nutrition-related RCT protocols

Data domainCategories used for data extraction
ParticipantsPregnant women
Mother and infant pairs
Infants
Children and preschool-aged children
Adults
The elderly
Adults and the elderly*
Postmenopausal women
Participants with a clinical condition (collect condition)*
InterventionsFood (whole food, food products, specially formulated foods)
Breast feeding, complementary feeding, weaning
Complete diet or dietary pattern*
Complete nutrition formulas (enteral or parenteral)*
Supplementation, or supplements, or fortification (single or multiple nutrients, bioactive non-nutrients, plant components)
Nutrition education, counselling and coordination of care*
Other, if no component of intervention could be categorised as any of the above
ComparatorPlacebo
No intervention
Usual care
Different intervention
Other
OutcomesMortality
Clinical status (clinical or biochemical measures)
Nutritional status (anthropometry, body composition, nutrition diagnosis)
Frequency or severity of disease
Diet quality and/or variety
Food/nutrient/dietary intake
Diet-related behaviours
Other non-dietary 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 design*Parallel RCT
Crossover RCT
Cluster RCT
Multicentre RCT
Single-centre RCT

  • *Our adaptations of the Naude et al.18 PICOS categories: to the participant categories, we added the category ‘adults and the elderly’ and expanded the category ‘participants with a clinical condition’ to also capture the clinical condition. To the intervention categories, we added ‘complete diet or dietary pattern’ and ‘enteral or parenteral complete nutritional formulas’ and removed ‘nutrition-related policies’. From the study design categories, we removed ‘observational and experimental non-randomised studies’ and included ‘cluster RCT’.

  • RCT, randomised controlled trial.