These recommendations are enormously influential, as they largely inform our ideas about healthy eating.
They also drive food and nutrition policy decisions, such as:
Congress stated that the Guidelines should be for the “general public.” Yet the agencies overseeing the Guidelines, the U.S. Departments of Agriculture and Health and Human Services (USDA-HHS) have interpreted this scope to mean that the Guidelines are only for “healthy Americans.”
A majority of Americans were indeed healthy in 1980 – when the Guidelines were launched – yet today, this is no longer the case.
The continued focus by USDA-HHS exclusively on “healthy Americans” has grave ramifications and limitations, since:
such that future editions focus on the general public across the entire life span, including all Americans whose health could benefit by improving diet…”
That 2017 report by the National Academies of Sciences, Engineering, and Medicine (NASEM) recognized this problem and stated:
“To develop a trustworthy DGA, the process needs to be redesigned.”
NASEM recommended upgrading the the scientific review process for the Guidelines, to a state-of-the-art methodology that would ensure more reliability in the Guidelines process. NASEM said:
“The DGA has to be based on the highest standards of scientific data and analyses to reach the most robust recommendations.“
NASEM recommended: “A redesigned process,” including:
“more rigorous methodological approaches to evaluation of evidence…” such that analyses “be based on validated, standardized, and up-to-date methods and processes.”
The Dietary Guidelines Advisory Committee assigns a grade to the quality of the science for each question studied (e.g., what is the relationship between a vegetarian diet and cardiovascular disease?). There are four grading options:
I. “Strong” represents a conclusion statement supported by a “large, high-quality body of evidence that addresses the topic.” Ideally, this should include multiple clinical trials, since this is the type of study that can demonstrate cause-and-effect. The level of certainty should be high, unlikely to change, and generalizable to the population of interest.
II. “Moderate” represents a conclusion statement with sufficient evidence, but the level of certainty is restricted by the amount of evidence, inconsistency in the findings, or methodological or generalizability concerns.
III. “Limited” represents a conclusion statement that is substantiated by insufficient evidence, and certainty is severely restricted by the amount of evidence, inconsistent findings, or methodological or generalizability concerns.
IV. “Grade not assignable” means a conclusion statement cannot be drawn due to the lack of evidence, or the evidence that is available has severe methodological concerns.