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Good review practice: a researcher guide to systematic review methodology in the sciences of food and health

Feasibility Assessment

Assessing necessity and relevance of the research question

It is important to check the intended SR topic for currency and novelty before conducting a systematic review to reduce the risk of conducting a redundant review.

There are various repositories and protocol registration platforms for food and nutrition associated topics within the context of human health. Food related reviews within the context of social sciences and environment are often archived by relevant institutes and indexed by relevant journal publishers. Repositories and organisations that may store food related systematic reviews are introduced here.

For other subject areas, a preliminary literature review can identify systematic review studies that are already available about the topic. It is important to plan and search all relevant databases including both multidisciplinary and subject­ specific databases to avoid missing any relevant reviews. You can find a list of food related databases here.

To narrow a search within a database to systematic reviews, add words like (review OR meta-analysis OR meta-analysis) to your search. If a database includes a filter for reviews, run an additional search without the (review OR meta-analysis OR meta-analysis) string. This filter will include reviews that are not systematic reviews, but the pool of results will be much smaller than a topic search without the filter


Availability of Evidence 

Both quantity and quality of the available studies are determining factors in the feasibility of taking a systematic review approach. Once you know you have a research question that is valid, it is important to identify all sources of information and weigh the quality and quantity against the objective(s) of the intended review.

Lack of high-quality evidence is more likely to apply when a niche topic or a topic in an emerging field with limited background research is considered for review. Where financial interests of certain institutes or parties limit access to potential data sources it can be impossible to run an unbiased review.

An effective and quick method of estimating the extent and volume of evidence is scoping the topic before planning a full systematic review.

When a review question is already restricted by the topic (e.g., to a subpopulation or a specific study design), it is essential to identify where other appropriate sources of evidence are collected or maintained (e.g., government reports, unpublished studies, or relevant research institutes in the field). In such cases contacting lead researchers, organisations, and special collections through research platforms and websites could help. You can also find more on where to search for non-peer-reviewed sources in here.


Availability of resources 

Conducting high quality systematic review studies requires an expert knowledge of the topic and good understanding or experience of the methodology. Before or while detailing a review question, plan external inputs and identify people with appropriate knowledge and skills to consult their views accordingly. These might include funders, commissioners, stakeholders, consumers, advisory board members as well as librarians, information specialists and data statisticians. Considering potential parties and stakeholders to carry out the work in collaboration is useful when resources (time or budget) are limited.

Systematic reviews are resource intensive projects, and they require extensive literature searching and documentation. Securing access to the most and best relevant databases for comprehensive literature searching is crucial. Also, planning to use an appropriate reference management tool is critical for recording and managing references from the beginning of the project. The cost of subscription to relevant databases and reference management tools should be considered in budget planning.

Depending upon your affiliation, you may have access to many databases through a university library or other organisations. For researchers in Lower and Middle Income Countries (LMICs) it is worth checking if your research organisation is eligible for membership in Research4Life, which provides free or low-cost access to over 154,000 resources, including many databases.

Using the most relevant databases and supportive automation tools can help reviewers make the most of their valuable time and conduct high quality reviews. Currently a fair number of software packages designed for conducting systematic reviews is available which can help with automation and speed up the process. You can find a list of food-related databases here and for available tools here.