About PEN

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Today's busy practitioners are challenged to stay abreast of current science in food and nutrition in an ever-changing environment, ensuring their advice is grounded in the latest evidence. While diet manuals and textbooks served practitioners well in the past as authoritative resources on clinical and other nutrition-related topics, they are limited in their scope and are often out of date even before they are published. To address the need of health professionals to be effective knowledge managers with ready access to timely, current and authoritative guidance on food and nutrition questions encountered in every day practice Dietitians of Canada has developed PEN - the Global Resource for Nutrition Practice.

A Dynamic Service
PEN:Practice-based Evidence in Nutrition(R) is a dynamic knowledge translation subscription service developed by Dietitians of Canada with input from thought leaders in dietetic practice, knowledge translation and technology.  The PEN service is now governed by a collaborative partnership comprised of the British Dietetic Association, the Dietitians Association of Australia and Dietitians of Canada. Learn more about our partners and contributors.
It’s powerful search tools and “Knowledge Pathway” format deliver evidence-based guidance to your nutrition practice questions easily and efficiently.  

Topics in PEN address the broad spectrum of practice in nutrition and dietetics including institutional care, primary health care, public/community health, consulting/private practice, food service management, professional education, food and the pharmaceutical industry and government. Recognized authorities on each topic or Knowledge Pathway addressed in PEN contribute to the identification of relevant literature from filtered and original sources and critically appraise, grade and synthesize that literature into key practice points or answers to practice questions. Additionally, best practice client and professional resources and other tools that are congruent with the evidence are included in PEN to support practice, along with standard Knowledge Pathway tools including backgrounds, evidence summaries and toolkits. As new science emerges, components of a Knowledge Pathway are updated in a timely way to ensure practice guidance always keeps in-step with change. Each Knowledge Pathway undergoes a complete review at regular intervals. Whether you are looking for a succinct answer to a practice question when you are pressed for time, or you want to review the evidence in more depth, PEN is the practice tool for all reasons.

It is essential that the development of evidence-based tools for practice guidance is not biased through the influence of commercial entities that may stand to benefit from the PEN service and its recommendations. As such, DC does not accept corporate sponsorship for the production or updating of practice guidance provided in the knowledge pathway content of PEN. DC does not host or receive funding from advertising or from the display of commercial content on the PEN website.  All PEN authors and reviewers are required to complete a Declaration of Affiliations and Interests Form that is kept on file with Dietitians of Canada. 

Resources and or tools that have been developed by the corporate sector may be eligible for inclusion in PEN if they are reviewed through an independent peer review process and deemed congruent with the evidence in PEN. However, preference will always be given to tools that have not been developed by corporate interests, should similar tools exist.

Funding for PEN has been provided by professional associations, subscription and licensing revenues, government grants and health authorities. View the key contributors to PEN

PEN Protocol for Finding the Evidence

In developing the content for PEN, validated and refined filtered information sources including synopses, well-conducted systematic reviews (such as Cochrane Reviews) and reputable practice guidelines have formed the basis for the evidence synthesis. Where filtered sources fail to address practice questions, PubMed is used to identify relevant and scientifically valid articles for analysis, and synthesis. Extensive web searches for grey literature and unpublished resources are also used to find relevant materials referenced in PEN. This top down hierarchical approach to retrieving and synthesizing the literature is recommended as appropriate for busy practitioners by several authorities in knowledge translation (1-3).

Evidence Grading  

Key practice points in PEN have been assigned an evidence grade by the Knowledge Pathway author.  References 1, 3-8 were consulted in determining the PEN grading protocol.

Level A - the conclusion is supported by good evidence [i.e. The evidence consists of results from studies of strong design for answering the question addressed. The results are both clinically important and consistent with minor exceptions at most. The results are free of any significant doubts about generalizability, bias, and flaws in research design. Studies with negative results have sufficiently large samples to have adequate statistical power.]
Level B- the conclusion is supported by fair evidence [i.e. The evidence consists of results from studies of strong design for answering the question addressed, but there is some uncertainty attached to the conclusion because of inconsistencies among the results from the studies or because of minor doubts about generalizability, bias, research design flaws, or adequacy of sample size. Alternatively, the evidence consists solely of results from weaker designs for the question addressed, but the results have been confirmed in separate studies and are consistent, with minor exceptions at most.]
Level C - the conclusion is supported by limited evidence or expert opinion [i.e. The evidence consists of results from studies of strong design for answering the question addressed, but there is substantial uncertainty attached to the conclusion because of inconsistencies among the results from different studies or because of serious doubts about generalizability, bias, research design flaws, or adequacy of sample size. Alternatively, the evidence consists solely of results from a limited number of studies of weak design for answering the question addressed.  Finally, the support for a particular opinion may consist of statement of informed, respected authorities based on their experiences, descriptive studies of reports of expert panels.] 
Level D evidence is from limited studies that are either such poor quality or too conflicting that no conclusions can be made. - No evidence from either authoritative sources or research involving humans was found.

See the PEN Writer’s Guide for a full description of the PEN approach to retrieval, synthesis and grading of evidence. http://www.pennutrition.com/WriterGuide.aspx

User Evaluation of PEN as a Knowledge to Practice Tool  

Dietitians of Canada collaborated with researchers in the Department of Applied Nutrition, Mount Saint Vincent University to evaluate the effectiveness of PEN as a knowledge translation and transfer tool for incorporating new knowledge into dietetic practice9. Respondents overwhelmingly endorsed PEN’s effectiveness:

•          92% indicating they were confident with the quality of PEN information

•          88% agreed that PEN enabled them to take an evidence-based approach to practice

•          82% agreed that PEN had positively changed the way they work.


The PEN database has an impressive track record of providing standardized, evidence-based responses to over 90% of caller inquiries received in two Canadian dietitian call centres.

  1. Gray GE, Gray LK. Evidence-based medicine: applications in dietetic practice. J Am Diet Assoc. 2002 [cited 2005 25 Aug];102:1263-72. Abstract available from:http://www.ncbi.nlm.nih.gov/pubmed/12792624
  2. Grandage KK, Slawson DC, Shaughnessy AF. When less is more: a practical approach to searching for evidence-based answers. J Med Libr Assoc. 2002 Jul [2005 25 Aug];90(3):298-304. Abstract available from: http://www.ncbi.nlm.nih.gov/pubmed/12113514
  3. Personal communication. R Hayward. Centre for Health Evidence. 2004.
  4. Canadian Task Force on Preventive Health Care. New grades for recommendations from the Canadian Task Force of Preventive Health Care. CMAJ. 2003 [cited 2005 25 Aug];169(3):207-8.  Citation available from: http://www.ncbi.nlm.nih.gov/pubmed/12900479
  5. Upshur, REG. Are all evidence-based practices alike? Problems in the ranking of evidence. CMAJ.2003 [cited 2005 25 Aug];169(7):672-3. Citation available from: http://www.ncbi.nlm.nih.gov/pubmed/14517125
  6. Schremann HJ, Best D, Vist G, Oxmann AD; GRADE Working Group. Letters, numbers, symbols and words: how to communicate grades of evidence and recommendations. CMAJ. 2003 [cited 2005 25 Aug];169(7):677. Abstract available from:http://www.ncbi.nlm.nih.gov/pubmed/14517128
  7. Ebell MH, Siwek J, Weiss BD, Woolf SH, Susman J, Ewigan B, et al. SORT: a patient centered approach to grading the literature. Am Fam Physician. 2004 [cited 2005 25 Aug];69(3):548-56. Abstract available from:http://www.ncbi.nlm.nih.gov/pubmed/14971837
  8. GRADE Working Group. Grading quality of evidence and strength of recommendations. BMJ. 2004 [cited 2005 25 Aug];328:1490. Available from:http://www.bmj.com/content/328/7454/1490.full
  9. Evaluation of Practice-based Evidence in Nutrition [PEN]. Final Report to the Canadian Council on Learning. April 2009 [cited 2010 14]


Learn more about the features of PEN