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Table 1 Characteristics of the included studies

From: Adherence to Mediterranean diet associated with health-related quality of life in children and adolescents: a systematic review

Author, publication year

Country

Study design

Total subjects

Inclusion criteria

Characteristics of participants

MD adherence

scoring system

MD adherence dimensions

HRQoL measure

HRQoL dimensions

Adjusted variables

Funding

Gender and age

BMI (kg/m2)

Physical activity

Weight

Costarelli et al., 2012 [14]

Greece

Cross-sectional

359 (13–16 years old)

Participants signed consent forms and received a full verbal and written explanation of the purpose of the study and its anonymous nature

46.2% boys Median age: 13.1 years (IQR: 0.5)

19.9 (SD, 3.2)

NR

Normal weight: 80.6% Overweight: 15.6% Obesity: 2.5%

KIDMED index

16 dichotomous items (yes/no): 12 items: behaviors consistent with the Mediterranean diet 4 items: behaviors inconsistent with the Mediterranean diet

KIDSCREEN-27

5 Dimensions: 1. Physical well-being (5 items) 2. Psychological well-being (7 items) 3. Parent relations and autonomy (7 items) 4. Social support and peers (4 items) 5. School environment (4 items)

Number of meals, number of meals (with family), BMI, obesity, father’s education level, mother’s education level, gender

Institutional support. Human Ecology Laboratory, Department of Home Economics and Ecology, Harokopio University of Athens

Muros et al., 2017 [15]

Spain

Cross-sectional

456 (11–14 years old)

Twenty-four adolescents were excluded for failing to complete some testing element or failing to attend class on their testing day

48.5% boys Mean age: 12.57 years (SD, 1.17)

19.75 (SD, 3.85)

PAQ-C score: 2.92 (SD, 0.64)

Normal weight: 75.7% Overweight: 16.7% Obesity: 5.5%

KIDMED index

16 dichotomous items (yes/no): 12 items: behaviors consistent with the Mediterranean diet 4 items: behaviors inconsistent with the Mediterranean diet

KIDSCREEN-27

5 Dimensions: 1. Physical well-being (5 items) 2. Psychological well-being (7 items) 3. Parent relations and autonomy (7 items) 4. Social support and peers (4 items) 5. School environment (4 items)

BMI, physical activity

NR

Zervaki et al., 2017 [16]

Greece

Cross-sectional

400 (14–17 years old)

Participants that signed consent forms received a full verbal and written explanation of the purpose of the study and its anonymous nature

49.5% boys Median age: 15.8 years (IQR: 1.03)

21.7 (SD, 3.1)

NR

Normal weight: 75.0 Overweight: 21.5 Obesity: 3.5%

KIDMED index

16 dichotomous items (yes/no): 12 items: behaviors consistent with the Mediterranean diet 4 items: behaviors inconsistent with the Mediterranean diet

KIDSCREEN-27

5 Dimensions: 1. Physical well-being (5 items) 2. Psychological well-being (7 items) 3. Parent relations and autonomy (7 items) 4. Social support and peers (4 items) 5. School environment (4 items)

Number of meals, number of meals (with family), age, obesity, father’s education level, mother’s education level, BMI

NR

Evaristo et al., 2018 [17]

Portugal

Cross-Sectional

946 (12–18 years old)

All students that agreed to participate in the study

53.3% boys Mean age: 14.5 years (SD, 1.8)

21.1 (SD, 3.8)

NR

NR

KIDMED index

16 dichotomous items (yes/no): 12 items: behaviors consistent with the Mediterranean diet 4 items: behaviors inconsistent with the Mediterranean diet

KIDSCREEN-10

It contains 10 items regarding family life, peers, and school life

Physical fitness, age, sex, pubertal stage (Tanners A and B), socioeconomic status, sleep duration, BMI

Portuguese Foundation for Science and Technology (FCT) grants

Esteban-Gonzalo et al., 2019* [18]

Spain

Cross-Sectional

(a) 536 children at primary school (6–7 and 9–10 years old)

(b) 987 adolescents at secondary school (12–13 and 15–16 years old)

(i) To study in the first/fourth grades (6–7 and 9–10 years old, respectively) for children and seventh/tenth grades (12–13 and 15–16 years old, respectively) for adolescents at baseline and (ii) to not have physical disability or health problems, which may limit the levels of physical activity

Primary school: 49.8% boys Mean age: 8 years (SD, 1.5) Secondary school: 51.3% boys Mean age: 8.2 years (SD, 1.5)

NR

NR

Overweight and obesity Primary school: Boys: 35.6% Girls: 36.9% Secondary school: Boys: 39.0% Girls: 21.9%

KIDMED index

16 dichotomous items (yes/no): 12 items: behaviors consistent with the Mediterranean diet 4 items: behaviors inconsistent with the Mediterranean diet

KIDSCREEN-10

It contains 10 items regarding family life, peers, and school life

Age, socio-economic status, prevalence of overweight, and obesity

DEP 2010- 21,662-C04-00 grant from the National Plan for Research, Development and Innovation (R + D + i)

Ferrer-Cascales et al., 2019 [19]

Spain

Cross-Sectional

527 (12–17 years old)

NR

45.5% boys Mean age: 14.43 years (SD, 1.52)

NR

NR

NR

KIDMED index

16 dichotomous items (yes/no): 12 items: behaviors consistent with the Mediterranean diet 4 items: behaviors inconsistent with the Mediterranean diet

KIDSCREEN-52

10 Subscales: 1. Physical Well-Being 2. Psychological Well-Being 3. Mood and Emotions 4. Self-Perception 5. Autonomy 6. Parent Relations and Home Life 7. Financial Resources 8. Social Support and Peers 9. School Environment 10. Social Acceptance

NR

Self-funded

Delgado-Floody et al., 2020 [20]

Chile

Cross-Sectional

619 (10–13 years old)

(i) To be a student of a public school in the La Araucanía region, (ii) to have a regular physical education class and (iii) to be aged between 10 and 13 years. The exclusion criteria were as follows; (i) having musculoskeletal disorders or (ii) any other known medical condition, which may alter the participant’s health and PA levels; and (iii) to have scholars commitment that they could be interrupted by the study measurements

55.9% boys Mean age: 11.72 years (SD: 1.07)

21.57 (SD, 4.68)

NR

Normal weight: 50.4% Overweight: 25.2% Obesity: 24.4%

Krece Plus test

The questionnaire contains 15 items, where the maximum possible score was + 11 and the minimum was − 5. Each item has a score of + 1 or − 1, depending on whether it approximates the ideal of the MD. The total points are accounted and, according to the score, the nutritional status is classified as follows: (1) “low” nutritional level, ≤ 5; (2) “moderate” nutritional level, 6–8; and (3) “high” nutritional level, ≥ 9

KIDSCREEN-10

It contains 10 items regarding family life, peers, and school life

Age, sex

Research Project R01/18 from the Universidad de Los Lagos and by private fundings

Rodriguez-Rosado et al., 2020 [21]

Spain

Cross-Sectional

114 (8–10 years old)

Parents/tutors of participants signed informed consent

Male: 9.53 years (SD, 0.64) Female: 9.54 years (SD, 0.6)

Male: 18.8 (SD, 4.52) Female:18.4 (SD, 4.19)

PAQ-A: Male: 3.82(0.76) Female:3.56 (0.83)

NR

KIDMED index

16 dichotomous items (yes/no): 12 items: behaviors consistent with the Mediterranean diet 4 items: behaviors inconsistent with the Mediterranean diet

KIDSCREEN-27

5 Dimensions: 1. Physical well-being 2. Psychological well-being 3. Autonomy and relationship with parents 4. Social relationships and Peer pressure 5. School environment

NR

NR

Caamaño-Navarrete et al., 2021 [22]

Chile

Cross-Sectional

634 (11–13 years old)

Chilean schoolchildren aged between 11 and 13, without musculoskeletal disorders or any other known medical conditions that may alter the participants’ health and PA levels

55.5% boys Mean age: 11.95 years (SD, 0.85)

21.6 (SD, 4.58)

2.64 h/week (1.42)

NR

KIDMED index**

Each item has a score of + 1 or – 1, depending on whether it approximates the ideal of the MD. The sum of all values from the administered test is categorized into three different levels: (1) > 8, optimal MD; (2) 4–7, improvement needed to adjust intake to Mediterranean patterns; and (3) ≤ 3, very low diet quality

KIDSCREEN-10

It contains 10 items regarding family life, peers, and school life

NR

NR

Mitri et al., 2021 [23]

Lebanon

Cross-Sectional

798 (11–18 years old)

Students suffering from physical disabilities or who were absent on the days of the data collection were not invited to participate in the study

52.9% boys Mean age: 15 years (SD, 2.07)

NR

PAQ C/A: 2.46 (0.75)

Normal weight: 55.4% Overweight: 20.2% Obesity: 19.3%

KIDMED index

16 dichotomous items (yes/no): 12 items: behaviors consistent with the Mediterranean diet 4 items: behaviors inconsistent with the Mediterranean diet

KIDSCREEN-27

5 Dimensions: 1. Physical well-being 2. Psychological well-being 3. Autonomy and relationship with parents 4. Social relationships and Peer pressure 5. School environment

School type, grade, age, skipping meals, father's education level, number of meals, number of meals with family, and physical activity

Self-funded

Mozzillo et al., 2021 [24]

Italy

Cross-sectional

420 (13–17 years old)

Age 13.0–17.0 years; Caucasian ethnicity; overweight or obesity; first visit at the outpatient clinic. The exclusion criteria were secondary causes of obesity (genetic, endocrine, or iatrogenic forms) and other chronic diseases or mental illnesses

44.5% boys Median age: 14.0 years (IQR: 13.2; 15.0)

31.2 (IQR: 28.7; 34.2)

0 h/week (0–3)

82.3 (IQR: 73.6; 93.2)

KIDMED index

16 dichotomous items (yes/no): 12 items: behaviors consistent with the Mediterranean diet 4 items: behaviors inconsistent with the Mediterranean diet

Pediatric Quality of Life Inventory (PedsQL)

4 Dimensions: 1. Physical functioning

2. Emotional functioning 3. Social functioning 4. School functioning

BMI, father’s education level (year), mother’s education level (year), exercise (hours/week)

Self-funded

  1. Data are presented as mean (SD) or median (IQR)
  2. *Originally a longitudinal study, it was considered the baseline cross-sectional cohort
  3. **The original article states that the Kreece Plus scale was used, but the KIDMED scale is cited and used
  4. Obesity classification (%) IOTF cutoff points, except in Delgado et al. and Mitri et al. classified with CDC criteria
  5. Self-reported score
  6. BMI (body mass index), MD (Mediterranean diet), HRQoL (Health-Related Quality of Life), KIDMED (Mediterranean Diet Quality Index), KIDSCREEN (KIDSCREEN test), PedsQL (Pediatric Quality of Life Inventory), Krece Plus (Krece PLus test), SD (standard deviation), IQR (interquartile range), NR (not reported), PAQ-C (Physical Activity Questionnaire for Older Children, a five-point scale), PAQ-A (Physical Activity Questionnaire for Adolescents, a five-point scale), PAQ C/A (Physical Activity Questionnaires for Children and Adolescents, a five-point scale)