Primary Research vs. Review Articles

Primary Research Articles

Reports of original research.
Test hypotheses by presenting novel analyses of data not considered or addressed in previous reports.
Typically consist of distinct sections that reflect the stages in the research process.

Introduction: Development of the problem under investigation, including a statement of the purpose of the investigation.
Methods: Description of the procedures used to conduct the investigation (sometimes with variations, such as Materials and Methods).
Results: Report of the findings (usually followed with charts and statistical tables).
Discussion: Summary, interpretation, and implications of the results.

Thompson B, Waterhouse M, English DR, et al. Vitamin D supplementation and major cardiovascular events: D-Health randomised controlled trial. BMJ. 2023;381:e075230. doi:10.1136/bmj-2023-075230
Manson JE, Cook NR, Lee IM, et al. Vitamin D supplements and prevention of cancer and cardiovascular disease. N Engl J Med. 2019;380(1):33-44. doi:10.1056/NEJMoa1809944

Literature reviews, including research syntheses and meta-analyses, are critical evaluations of material that has already been published.
In meta-analyses, authors use quantitative procedures to statistically combine the results of many studies.
Authors analyze and evaluate current research and investigations related to a specific topic, field, or problem.
Not primary sources since they review previously published material.
Organize, integrate, and evaluate previously published material to consider the progress of research toward clarifying a problem.
Often as lengthy or even longer than original research articles.
Can be of great value for identifying potentially good primary sources, but they aren't primary themselves.

Define and clarify the problem.
Summarize previous investigations to inform the reader of the state of research.
Identify relations, contradictions, gaps, and inconsistencies in the literature.
Suggest the next step or steps in solving the problem.

de la Puente Yagüe M, Collado Yurrita L, Ciudad Cabañas MJ, Cuadrado Cenzual MA. Role of vitamin D in athletes and their performance: Current concepts and new trends. Nutrients. 2020;12(2):579. doi:10.3390/nu12020579

Read the abstract to get a sense of the kind of article being presented; a review article abstract should make that clear.
Absence of an abstract may indicate it is not a primary resource.
Short research articles may not include all elements; look for phrases like "we tested" and "in our study, we measured" to identify original (primary) research.