Nutrition Evidence Library (NEL) is being redesigned. In the meantime, all of the content from remains fully accessible through the links below.

If you are having trouble locating information you found previously at, please email


The United States Department of Agriculture’s (USDA) Nutrition Evidence Library (NEL) is an entity that specializes in conducting systematic reviews (SRs) to inform Federal nutrition policy and programs.

The NEL has dedicated staff that collaborates with leading scientists to objectively review, evaluate, and synthesize research using state-of-the-art methodology to answer important food- and nutrition-related public health questions. The NEL is not a repository of all food and nutrition literature, nor is it a search engine or database. The NEL is managed and staffed by the USDA’s Center for Nutrition Policy and Promotion.

The NEL uses a rigorous, protocol-driven methodology designed to minimize bias; to ensure that systematic reviews are relevant, timely, high quality, and reproducible; and to maximize transparency. The six-step process of a NEL systematic review is described below, and additional information about NEL’s methodology can be found on the About the NEL webpage:

  1. Topic identification and systematic review question development
  2. Literature search, screening, and selection
  3. Data extraction and risk of bias assessment
  4. Evidence description and synthesis
  5. Conclusion statement development and evidence grading
  6. Identification of research recommendations

For more information about the NEL and its projects, go to the following pages:

Have a question about the NEL? Email us at