Letter to Editor: a cautionary note about "Dietary diversity score and cardio-metabolic risk factors: an updated systematic review and meta-analysis".

In the Journal's recent issue, Qorbani and colleagues conducted a systematic review and meta-analysis to determine if a dietary diversity score is associated with cardio-metabolic outcomes. Given the importance of evidence synthesis for nutrition policy and practice, robust review methodology is necessary to avoid spurious conclusions about the health impacts of a mixed diet. There are important conceptual and methodological issues unique to this nutrition topic that warrant consideration and attention and that raise concerns for internal validity of the review. We write to emphasise the need for readers' caution when interpreting this research evidence.