1. Summary of the intervention details (using TIDieR^a items) for each RCT in the systematic review.

Recipients	Why	What (materials)	What (procedures)	Who provided	How and where	When and how much	Strategies to improve or maintain intervention fidelity; tailoring and modification	Extent of intervention fidelity
Tershakovec 1998 (RCT)
4‐ to 9‐year‐old children with hypercholesterolaemia (plasma total cholesterol > 4.55 mmol/L, fasting plasma LDL‐C 2.77‐4.24 mmol/L for boys and 2.90‐4.24 mmol/L for girls), at ≥ 85% of ideal body weight.	Limited dietary fat was recommended for children aged > 2 years, but there were concerns that lower fat intake of children may affect their growth. Trial evaluated growth of children with hypercholesterolaemia completing an innovative, physician‐initiated, home‐based nutrition education programme or standard nutrition counselling that aimed to lower dietary fat intake.	Nutrition education programme complied with recommendations of the National Cholesterol Education Program Expert Panel on Blood Cholesterol Levels in Children and Adolescents.	Children and ≥ 1 parent (usually mother) attended 45‐ to 60‐minute counselling session with paediatric dietician. Children and parents in at‐risk control and not‐at‐risk control groups were not provided educational information or materials.	1) Not described; 2) paediatric registered dieticians.	1) Audiotape stories and picture books and follow‐up paper/pencil activities for children as well as manual for parents. Story and activities to be completed each week; 2) face‐to‐face individual counselling by a dietician. 1) At home; 2) paediatric practice.	10 weeks with 1) talking‐book lesson; 2) 45‐60 minutes counselling session each week.	Not described Tailoring and modification of intervention during trial were not described.	1) 71/88; 2) 77/86 completed intervention programmes and returned for evaluation at 3 months after baseline.
Obarzanek 2001 (RCT)
Prepubertal boys and girls aged 8‐11 years with LDL‐C levels ≥ 80th and < 98th percentiles for age and sex percentiles of the Lipid Research Clinics population.	Aimed to assess feasibility, safety, efficacy and acceptability of lowering dietary intake of total fat, saturated fat and cholesterol to decrease LDL‐C levels.	Intervention group received dietary counselling sessions based on National Cholesterol Education Programme guidelines: 28% of energy from total fat, < 8% from saturated fat, > 9% from polyunsaturated fat, and < 75 mg/1000 kcal of cholesterol per day, not to exceed 150 mg/day. Guidebooks including activities and recipes on diets and food recommendations given to participants and their families.	In first 6 months, 6 weekly and then 5 biweekly group sessions were led by nutritionists and behaviourists, and 2 individual visits were held with nutritionist. Over second 6 months, 4 group and 2 individual sessions were held. During 2nd and 3rd years, group and individual maintenance sessions were held 4‐6 times/year, with monthly telephone contacts between group sessions. During 4th year of follow‐up, 2 group events + 2 individual visits conducted with additional telephone contacts as appropriate.	Nutritionists and behaviourists	1) Group sessions and 2) individual visits were held, accompanied by telephone contacts in between sessions. 1) At clinics, 2) at home	6 weekly, 5 biweekly group sessions and 2 individual visits during first 6 months; 4 group and 2 individual sessions during second 6 months; 4‐6 maintenance sessions with telephone contacts between sessions during 2nd and 3rd years; 2 group and 2 individual sessions with telephone contacts as appropriate by 4th year.	By 4th year of follow‐up, individual visits used an individualised approach based on motivational interviewing and stage of change for increasingly busy teenagers. Tailoring and modification of intervention during trial not described.	295/334 attended the last visit (> 5 years' follow‐up).
Mihas 2010
Students aged 12‐13 years from an urban area in Greece.	Aimed to evaluate the short‐term (15‐day) and long‐term (12‐month) effects of a 12‐week school‐based health and nutrition interventional programme regarding energy and nutrient intake, dietary changes and BMI.	Teaching material for teachers and workbooks for students on nutrition‐dietary habits and physical activity and health based on Social Learning Theory Model were developed and distributed to teacher and each student.	Multicomponent workbooks covering mainly dietary issues, but also dental health hygiene and consumption attitudes, were produced with each student being supplied a workbook. The class home economics teacher implemented 12‐hour‐classroom curriculum incorporating health and nutrition promotion during 12 weeks. 2 meetings were conducted with parents (given screening results of children; presentations given on dietary habits of children to improve health profile of children and prevent development of chronic diseases in the future). Cues and reinforcing messages in the form of posters and displays were provided in the classroom.	Educational intervention (classroom curriculum) delivered by class home economics teachers who were trained and supervised by health visitor or family doctor.	Classroom curriculum; cues and reinforcing messages in the form of posters and displays provided in classroom; nutrition education meetings for parents in group. At school.	12 hours of classroom material, 2 meetings for parents during a 12‐week period.	Health visitor or family doctor supervised the programme implementation of class home economics teachers who were given 2 × 3‐hour seminars with aims to familiarise teachers about objectives of intervention and their role therein, and to increase their awareness of significance of incorporating health and nutrition in their curriculum before delivering the intervention. Tailoring and modification of intervention during trial not described.	107/109 participation rates at 15‐days' follow‐up and 98/109 at 12 months' follow‐up.

^aTIDieR: Template for Intervention Description and Replication, template for this table from Hoffman 2017.

BMI: body mass index; LDL‐C: low‐density lipoprotein cholesterol; RCT: randomised controlled trial.