Food and Nutrition

A literature review is a critical assessment of the literature relating to a particular topic or subject. It aims to be systematic, comprehensive and reproducible. The goal is to identify, evaluate and synthesise the existing body of evidence that has been produced by other researchers with as little bias as possible.

Literature reviews take different forms. Some literature reviews are standalone projects. If you search the literature in food science and nutrition, you’ll find examples of:

• Mapping and scoping reviews, which review existing literature in order to identify opportunities for further research. 
• Reviews distilling the latest information to present the state-of-the-art understanding on a question or the latest updates on a methodology.
• Systematic reviews, which are a unique form of literature review:  they are research studies of research studies, and their searches need to find all the research that's been done on their question whether it's been published or not.  Conducted following a precise protocol, some systematic reviews include meta-analysis which extracts the data from all the quality research found and compiles it into a comprehensive data set in order to assess the current state of evidence on a question. Big projects, they generally take between 12 to 24 months to conduct.
• Rapid reviews are quicker versions of systematic reviews, with some of the steps simplified or omitted.

Review types include many variations and nuances, as well as overlap. For instance, a rapid review might conclude that more and better research is required on a question, and hence intersect with the purpose of a scoping review.  This is just a small sampling of the variations of standalone review types out there—a recent study identified forty-eight distinct types of reviews within health disciplines alone!* 

*Sutton, A. et al. (2019) ‘Meeting the review family: exploring review types and associated information retrieval requirements’, Health Information and Libraries Journal, 36(3), pp. 202–222. doi: 10.1111/hir.12276.

Most literature reviews are not self-contained projects. A literature review is a key component of any advanced research project. 

Primary research articles begin with a literature review in their introduction which surveys the existing research, and indicates the significance of the article’s research, and places it in context. Researchers then may pull elements of the literature into the discussion section of the article, by showing how their research compares to existing research, possibly expanding on it, or contradicting its conclusions, thus highlighting the significance of what their research has found.

PhD dissertations have extensive literature reviews, sometimes comprising a chapter or even two of the written project.  In other theses or dissertations a researcher might integrate their literature review into each section rather than writing it up into a distinct chapter.  However it is incorporated, the literature search and review is a crucial component of the project.