18.5: Guest Lecturer

Guest Lecturer: Suzanne P. Murphy, PhD, RD

The Long and Winding Road Toward Nutrition Standards A Personal Perspective

Nutrition standards are widely used by both health professionals and consumers, but the process of selecting accurate values is both expensive and time-consuming. I should know, because I’ve spent much of the past 25 years helping various committees and organizations set these standards.

The Dietary Reference Intakes (DRIs) are the nutrient standards used in the United States and Canada. They are set by the Food and Nutrition Board (FNB) of the National Academy of Science, Engineering, and Medicine (NASEM). Funding comes almost exclusively from various government agencies, such as the U.S. Departments. of Agriculture (USDA) and Health and Human Services (HHS), and Health Canada, which specify the type of work to be done. However, the selection of the DRI committees, and their deliberations, are decided by the FNB. Typically, a committee will be asked to set DRIs for a set of related nutrients, such as calcium and vitamin D (2011) or the revised recommendations for sodium and potassium released in 2019.

Names of potential committee members are solicited by FNB and must contribute to specified areas of expertise required, such as: basic nutrition science, epidemiology, clinical trials, public health, DRI methods, and statistics. Committee members are primarily university faculty members; neither food industry scientists, nor government researchers, are typically asked to serve on these committees, to reduce the risk of bias. At the first meeting of a committee, each member will declare any possible conflicts of interest (such as investments in a food company) and could be dismissed if the conflicts are serious. Furthermore, any strong opinions about the requirements for the nutrients of interest must also be revealed at this time, again with the intent of ensuring a balanced committee. I have served on several DRI committees because I have a wide knowledge of the DRI process, but also because I have never accepted industry funding for my research, nor invested personally in food companies.

The DRI committees meet in person several times, and also hold frequent conference calls to discuss the various scientific issues related to the requirements for the nutrients being considered. A DRI report often takes more than a year to complete, and in my experience, takes at least 10 hours a week of each member’s time. It is a major time commitment, all without compensation since the committee members are all volunteers!

All of these deliberations are confidential, and any breach is grounds for asking the committee member to resign. However, a few of the sessions are open to the public, during which anyone can make a brief presentation, and throughout the process, written comments from the public are encouraged. The FNB staff ensures that the committee’s discussions, and the resulting report, are thorough and based on the best evidence available. Committees must come to a consensus, meaning that every member agrees with the conclusions, so the discussions can be heated at times. In addition, a draft of the report is sent to a group of expert reviewers who are not part of the committee, usually about 15 scientists from a variety of disciplines. Typically, there are hundreds of suggestions from the reviewers, all of which must be addressed by the committee (either by making changes to the report, or explaining why a change is not needed). As a result of this rigorous process, any report from the NASEM is considered authoritative and is almost always accepted by scientific experts.

There are several parallels to the DRI process, but also some interesting differences in the way that the Dietary Guidelines for Americans (DGAs) are set. Currently, new DGAs are set every five years. The DGA process is overseen directly by the federal government agencies, and alternates between USDA and HHS as the lead agency. As with the DRIs, the first step in the DGA process is to convene an expert committee: the Dietary Guidelines Advisory Committee (DGAC), composed of experts whose names are submitted by various agencies and organizations, and then selected by USDA and HHS. Committee members are volunteers, and typically are university faculty members with expertise in dietary guidance. I was the Vice-Chair of the year 2000 DGAC, and it was certainly a memorable experience! Unlike the process for the DRIs, all meetings of the DGAC are open to the public, and all deliberations are posted online. It’s disconcerting (and a bit humbling) to see one’s every “um” and “ah” transcribed, but the meetings are certainly transparent!

The DGAC issues a report after almost two years and approximately 6 meetings. However, this report is not the DGA report. Instead, the government agencies take the text of the DGAC report, e.g., 445 pages including numerous appendices in 2010, and condenses it into a more user-friendly set of Dietary Guidelines, e.g., 95 pages in 2010. Although the DGA report is targeted to health professionals, the document is formatted and illustrated like a consumer publication. The DGAC is not involved in this step of the process, and the actual writing of the DGA document is not at all transparent. Although the DGA have always adhered to the intent of the DGAC report, there have sometimes been concerns about perceived omissions. A recent example is the focus of the 2015 DGAC report on including environmental considerations when issuing the DGAs. However, the 2015 DGA report from the government did not mention these considerations.

In conclusion, setting nutrition standards is a complex process. In an ideal world, standards for healthy nutrient intakes would be decided, and then would be the basis for setting standards for healthy food intakes. Both types of standards would be reviewed periodically, and updated as new science becomes available. Of course, in practice there are never sufficient funds to undertake such comprehensive reviews on an ongoing basis, so compromises must be made. Although the food standards (the DGAs) are reviewed every 5 years, there is no such recurring cycle for reviewing nutrient standards (the DRIs). Still, the current approach is remarkably thorough, and represents a consensus of scientists with many years of experience in the field. This consensus approach helps to ensure that outlier views do not prevail. In addition, because only peer-reviewed published evidence is considered, not anecdotal reports, the results are science-based as opposed to opinion-based. Although I sometimes complain about the weeks and months of my career that have been spent on these volunteer activities, I ultimately conclude that these are actually the professional contributions that have had the greatest impact on the health of Americans.

^{Dr. Murphy is an Emeritus Professor at the University of Hawaii Cancer Center where she conducted research on associations between diet and cancer. She is an elected member of the National Academy of Medicine and has been a member of several NAM consensus committees related to the DRIs. She also has participated in setting the Dietary Guidelines for Americans, as well as the development of the Healthy Eating Index. She has published over 150 peer-reviewed papers and has given presentations on nutrient standards at national and international meetings. Her numerous awards include the Excellence in Dietary Guidance Award from the American Public Health Association, the Monsen Award for Outstanding Research Literature from the Academy of Nutrition and Dietetics, and the Elvehjem Award for Public Service in Nutrition from the American Society for Nutrition.}