Twenty-four RCTs were included (n=approximately 35,316). Most studies had more than 1,000 participants. Study quality varied considerably. Four studies met more than 70% of items on the CONSORT checklist. The most common flaws were lack of: information on assessment of adherence to protocol; sample size calculation; randomisation methods; blinding; drop-outs; and reporting of adverse events.
Studies aimed at improving child dietary intake (four studies): One study reported significant positive changes in dietary outcomes in parental involvement groups. Two studies reported mixed results with outcomes that varied by gender. One study reported positive changes in dietary knowledge, but no changes in dietary intake.
Indirect parental involvement (19 studies): Seven studies reported significant changes in the desired direction in parental involvement groups. Seven studies reported mixed results. Five studies reported no significant intervention effects.
Direct parental involvement (five studies): Two studies reported significant changes in the desired direction in parental involvement groups. Three studies reported mixed effects.