Study designs of evaluations included in the review
Studies of experimental or quasi-experimental design were considered: these included randomised and non-randomised controlled trials, prospective cohort studies with concurrent controls, intervention studies with a historical control group, and retrospective controlled studies. Observational studies were excluded.
The duration of the included studies ranged from 3 days to 6 months.
Specific interventions included in the review
Studies were included if they focused on, or included as a component, interventions designed to promote healthy eating in pre-school children aged 1 to 5 years. Specific interventions included in the review were classified as follows:.
1. Healthy eating promotions aimed at children in a pre-school or day-care setting (7 studies):
A new nutrition education curriculum for 'Head Start' classrooms.
A teaching strategy based on 'threat' versus 'benefit', using traditional children's stories.
Nutrition education activities in the classroom.
Computer-based versus traditional nutrition education.
Verbal praise versus tangible rewards used as instrumental conditions to influence food preference.
'Look' versus 'taste' exposure to novel foods.
Video programmes showing healthy eating messages.
2. Healthy eating promotions aimed at children and combining pre-school and home settings (1 study):
Nutrition education curriculum with and without parental involvement.
3. Healthy eating promotions aimed at children and comparing pre-school and home setting (1 study):
Nutrition education programme delivered by teachers in a pre-school setting, or by parents at home.
4. Healthy eating promotions aimed at children in a home setting (1 study):
'Hearthrob', a home-based nutrition education programme.
5. Healthy eating promotions aimed at carers in combined primary care and home settings (1 study):
Regular advice on healthy diet and related organisational skills.
6. Healthy eating promotions targeting the parents of pre-school children (2 studies):
Weekly newsletters and nutrition education workshops.
Individualised counselling group, nutrition education in classroom setting and haemoglobin levels.
7. Healthy eating promotions aimed at day-care staff (1 study):
Texas nutrition education training programme.
Participants included in the review
The inclusion criteria specified that studies of healthy eating promotion interventions for children aged 1 to 5 years were eligible if their target populations were children, their parents, other family members, and other carers such as nurseries or nursery staff.
The actual age of the children in the included studies ranged from 6 months to 7 years; it was unclear whether data were extracted for all the children in the included studies, or only for those in the specified age range of 1 to 5 years. The majority of included studies (11) were of children aged at least 3 years. The socioeconomic backgrounds and ethnicity of participants varied widely across the studies. One study only included anaemic children.
Studies of participants living in institutions and of high-risk populations, i.e. obese infants and those with dietary fads and allergies were excluded, as were interventions aimed specifically at ethnic groups not represented widely in the UK population or based in non-industrialised societies.
Outcomes assessed in the review
Studies with evaluated outcomes measuring biomedical, anthropometric and dietary indices were included, as were studies addressing knowledge, attitudes, food choice and food behaviour.
How were decisions on the relevance of primary studies made?
The studies were assessed for their potential relevance by reading the titles, and abstracts where possible, and making a judgement based on the inclusion and exclusion criteria for validity. The authors do not state how many of the reviewers performed the selection.