Nutrition: the evidence base

A study design is shown for a completed, peer-reviewed paper. A registered protocol, a preprint, a conference abstract, a referee report or a book chapter has not been through peer review as a finished paper, so it is labelled for what it is, and it is counted in no source count. Where a record could not be confirmed as a completed paper at all, it says so rather than guessing. They all stay in the list, and their DOI still resolves, because the count of what was screened is part of the audit trail.

• Protocol / registration A registered plan for a review or trial, not its results.
• Preprint Posted by its authors before peer review.
• Conference abstract A conference summary rather than a peer-reviewed paper.
• Peer-review report A referee's report on a paper, not the paper itself.
• Guideline / position stand A recommendation derived from evidence, which is a step further from the data than the evidence itself.
• Book chapter A chapter in a scholarly book rather than a journal paper.
• Type not recorded Our record does not say what kind of publication this is, so it is counted in no source count. That is a gap in our data, not a judgement about the research.