How are the dietary guidelines generated?
Curious how dietitians come up with their dietary recommendations? Outlined below are different types of research studies ranked in from strongest to weakest evidence. Meta-analyses and systematic reviews compile many different studies to give the strongest recommendations. Randomized control trials are the gold standard for nutrition research since they reduce bias and can answer a question by changing a specific variable, however, can be expensive and require more resources than other study types. Observational studies can be influenced by recall bias and other confounding factors, as the variable of interest has not been isolated for study as in experimental studies.
Animal and other in vivo models provide a controlled and less expensive method to study outcomes than human studies, and provide greater ability for manipulation to really answer the one variable/question at hand. In combination with human studies, they can both answer more specific questions and provide basis to go into a human clinical trial. As a scientist, I currently conduct my research in a mouse model which allows me complete manipulation over their diet and other variables, which is hard to do with human studies. However, since they are mice and not humans, human studies are needed to confirm findings before recommendations can be made.
How do we get from research studies to dietary guidelines? The US Departments of Agriculture (USDA) and Health and Human Services (HHS) update and release the Dietary Guidelines for Americans every 5 years. They rely on a committee of experts in nutrition to review the current body of nutrition research and to recommend updates to guidelines accordingly. This committee uses the body of nutrition research collectively to inform their report, thus changes to the guidelines are based on evidence repeated in the literature of human nutrition studies…not just one exciting study conducted in a mouse model. This committee submits a report to the USDA and HHS, who then draft updated versions of the guidelines with the support and review of other government agencies (including the NIH, FDA, and CDC), before signing off on the final Dietary Guidelines.
The process for generating the dietary guidelines involves several steps:
Review of the scientific evidence: A team of scientists reviews the latest research on nutrition and health to identify areas where the evidence is strong enough to inform the development of recommendations.
Development of the report: The team of scientists writes a report summarizing the evidence and making recommendations based on that evidence.
Public review and comment period: The report is made available to the public for review and comment. Interested parties, including individuals, organizations, and government agencies, can provide feedback on the report.
Finalization of the guidelines: Based on the feedback received during the public review and comment period, the HHS and USDA consider any changes that should be made to the report and finalize the guidelines.
The process for generating the dietary guidelines is designed to develop recommendations are based on the best available scientific evidence and are intended to help people make informed choices about their diet and to promote overall health and well-being.
