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Types and Levels of Evidence for Nutrition/Dietetic Research

Describes different types of evidence and provides strategies for finding specific types of articles for Nutrition students

This page will provide you with information to differentiate an original research article from a review article.

What is an Original Research Article?

Features of an Original Research Article

Original research articles are considered primary research.

  • Purpose: Designed to share findings from original investigations that contribute new insights to a specific academic field.

  • Also Known As: Often labeled as an empirical study or empirical research article.

  • Structure: Commonly follows a standardized format, which includes sections such as:

    • Abstract – a brief summary of the study
    • Introduction – outlines the research question and background
    • Methods – details how the research was conducted
    • Results – presents the data collected
    • Discussion/Conclusion – interprets the findings and their implications
    • References – lists the sources cited

  • Example: A journal article reporting on a controlled experiment conducted by the authors, including data analysis and interpretation.

Example Article Types that Fall Under Primary Research

1. Permatasari DI, Sutjiati E, Sulistyowati E. Effect of Brown Rice Intervention on BMI and Waist Circumference in Patients with Type 2 Diabetes Mellitus. Ind J of Hum Nutr. 2023;10(1):77-87. doi:10.21776/ub.ijhn.2023.010.01.9

2. Liu Y, Fowler H, Wang DD, Barnes LL, Cornelis MC. Mediterranean-DASH intervention for neurodegenerative delay (MIND) trial: Genetic resource for precision nutrition. Nutrients. 2025;17(15):2548-2563. doi:10.3390/nu17152548

3. Plaza-Diaz J, Brandimonte-Hernández M, López-Plaza B, et al. Effect of a novel food rich in miraculin on the intestinal microbiome of malnourished patients with cancer and dysgeusia. Nutrients. 2025;17(2):246-266. doi:10.3390/nu17020246

What is a Review Article?

Features of a Review Article 

Review articles are considered a type of secondary research.

  • Purpose: Provides a detailed summary of existing research on a specific nutrition-related topic, offering a broad understanding of current knowledge.
  • Nature of Content: Instead of presenting new data, review articles synthesize findings from multiple studies to highlight trends, relationships, and gaps.
  • Value to Readers: Helps readers understand how scientific perspectives have evolved, identify areas needing further research, and recognize inconsistencies in the literature.
  • Example: An article reviewing recent studies on the impact of ultra-processed foods on cardiovascular health, comparing methodologies and outcomes to suggest future research directions.

Example Article Types that Fall Under Review Articles

1. Lane MM, Gamage E, Travica N, et al. Ultra-Processed food consumption and mental health: A systematic review and meta-analysis of observational studies. Nutrients. 2022;14(13):2568-2590. doi:10.3390/nu14132568

2. Pacenta J, Starkoff BE, Lenz EK, Shearer A. Prevalence of and contributors to food insecurity among college athletes: A scoping review. Nutrients. 2024;16(9):1346-1360. doi:10.3390/nu16091346

3. Karr T, Guptha LS, Bell K, Thenell J. Oxalates: Dietary Oxalates and Kidney Inflammation: A Literature Review. Integr Med: Clin Jour. 2024;23(2):36-44. Accessed October 7, 2025. https://www.imjournal.com/