Study designs of evaluations included in the review
Randomised controlled trials (RCTs) were eligible for inclusion in the review.
Specific interventions included in the review
Studies where at least one treatment arm comprised standard telephone-based counselling (live interventionist without a video stream) as the primary component were eligible for inclusion. In the included studies, telephone counselling was delivered by registered dieticians, registered nurses, counsellors, psychologists, health educators, information specialists and health students. Counselling was based on Social Cognitive Theory, themes from the Transtheoretical Model, and Motivational Interviewing. Interventions were supplemented with written nutrition information, personalised feedback letters, meal replacements, computerised assessments, group meetings, clinical follow-ups and e-counselling. Where reported, the average number of sessions was 3.4 (range: 1 to 7) over 23.4 weeks (range: 7 to 52), with an average call length of 16.5 minutes (range: 8 to 25). Control conditions included a nutrition assessment, advice and written information.
Participants included in the review
Studies of adults were eligible for inclusion. The majority of included participants were white, middle-aged women and many were reported to have existing cancer, diabetes or heart disease. Most of the studies were conducted in the USA.
Outcomes assessed in the review
Studies that reported direct assessments of fruit/vegetable or dietary fat consumption were eligible for inclusion. The secondary outcomes of interest were clinical end points such as blood-pressure, lipid profiles, weight loss and behavioural biomarkers. Dietary outcome measures were assessed by validated self-report instruments, while serum biomarkers were used as proxy measures in some studies. The outcome measures for dietary fat intake were varied.
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.