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FSN 265: Dietary Applications of Nutrition Principles: Research Articles

Primary vs. Secondary Research

It's important in this class that you understand the difference between primary and secondary research. If your instructor only wants you using primary resources, check out the below examples to better understand how to identify them.

Always feel free to reach out to your librarian if you're unsure if you have a primary article or not.

Original (Primary) Research Articles

Primary research articles were written by the people who conducted the experiment they're describing. Think of primary research as first-hand experiences. Below are some common details that can you help identify if what you're reading is primary research. 

Look for the following:

  • Details on research subjects (humans, animals, cells or tissues, health or vital statistics records)

"...The study was conducted in 20 obese patients (men) within the Coronary Diet Intervention With Olive Oil and Cardiovascular Prevention (CORDIOPREV) study..."1

"...Participants: Children born between November 1, 2001, and December 31, 2011, at 35 weeks' gestational age or older, with birth weight of 2000 g or more and in the fifth percentile or higher for gestational age, and who had a preventive health visit within 14 days of life and at least 2 additional visits in the first year of life..."2

  • Details on methods

"...Participants were randomized to receive the Med diet (35% fat, 22% monounsaturated) and the LFHCC diet (28% fat, 12% monounsaturated)..."1

"...Design and Setting: Retrospective, longitudinal study of singleton births and matched longitudinal study of twin pairs conducted in a network of 30 pediatric primary care practices serving more than 200,000 children of diverse racial and socioeconomic backgrounds across Pennsylvania, New Jersey, and Delaware..."2

  • Original results (numbers, tables, graphs or visualizations)

"...The LFHCC diet increased the Prevotella and decreased the Roseburia genera, whereas the Med diet decreased the Prevotella and increased the Roseburia and Oscillospira genera (P = .028, .002, and .016, respectively)..."1

"...Results: Of 38,522 singleton children (50% female; mean birth weight, 3.4 kg), 5287 (14%) were exposed to antibiotics during the first 6 months of life (at a mean age of 4.3 months). Antibiotic exposure was not significantly associated with rate of weight change (0.7%; 95% CI, -0.1% to 1.5%; P = .07, equivalent to approximately 0.05 kg; 95% CI, -0.004 to 0.11 kg of added weight gain between age 2 years and 5 years)..."2

Types of Information

[Header] Types of Scientific Resources

[Content] Primary:

Peer reviewed scientific research articles
Published Conference Proceedings
Technical Reports
Author Self-Archived Research
Edited Volumes


Review Articles
Non-Scholarly Publications (e.g. magazines)
Single Author Books



University of Maine Fogler Library

Some types of information are more likely to be primary. If you can identify what you're reading, it can be an important clue.

Not Primary Research

In secondary research articles, the authors are writing about experiments conducted by OTHER PEOPLE. The authors did not collect the data themselves. They might be analyzing someone else's work or looking for trends by studying a lot of research on the same topic. Below are some examples of what secondary research can look like. 

  • Secondary research--all done through the library (meta-analysis, systematic review)

"...A survey of all the available English language literature utilizing Medline on this topic was obtained and critically reviewed. The key words that were utilized were gut microbiota, diet and obesity..."3

  • Reports of or news about somebody else's research

"Bacteria in the intestines produce acetate, a short-chain fatty acid that works through the brain and nervous system to make rats and mice fat, researchers report in the June 9 Nature.

If the results hold up in humans, scientists would understand one mechanism by which gut microbes induce obesity..."4

  • Articles primarily about validating or testing new techniques or models (these are primary research articles, but not appropriate for this class)

"Here, we describe the CASINO (Community And Systems-level INteractive Optimization) toolbox, a comprehensive computational platform for analysis of microbial communities through metabolic modeling. We first validated the toolbox by simulating and testing the performance of single bacteria..."5


1. Haro C, Montes-Borrego M, Rangel-Zúñiga OA, et al. Two healthy diets modulate gut microbial community improving insulin sensitivity in a human obese population. J Clin Endocrinol Metab. 2016;101:233-242. doi:10.1210/jc.2015-3351.

2. Gerber JS, Bryan M, Ross RK, et al. Antibiotic exposure during the first 6 months of life and weight gain during childhood. JAMA. 2016;315:1258-1265. doi:10.1001/jama.2016.2395.

3. Bell DSH. Changes seen in gut bacteria content and distribution with obesity: causation or association? Postgrad Med. 2015;127:863-868. doi:10.1080/00325481.2015.1098519.

4. Saey TH. Microbial signals influence obesity. Sci News. 2016;190:7.

5. Shoaie S, Ghaffari P, Kovatcheva-Datchary P, et al. Quantifying diet-induced metabolic changes of the human gut microbiome. Cell Metab. 2015;22:320-331. doi:10.1016/j.cmet.2015.07.001.

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