Data collection and analysis
Two review authors independently assessed the eligibility of the studies. They also assessed the risk of bias and extracted data using
a modified version of the Cochrane Consumers and Communication Review Group data extraction template. Any discrepancies in
judgement were resolved by discussion and consensus, or with a third review author. Because the studies differed widely with respect
to interventions, measures of diet adherence, dietary advice, nature of the chronic diseases and duration of interventions and followup,
we conducted a qualitative analysis. We classified included studies according to the function of the intervention and present results
in a narrative table using vote counting for each category of intervention.