Since the U.S. Department of Health and Human Services (HHS) and U.S. Department of Agriculture (USDA) Jan. 7 release of the Dietary Guidelines for Americans, 2025-2030, many in the nutrition field – including those who served on the scientific advisory committee – have publicly questioned their scientific rigour and some of the key recommendations.
The approach to these guidelines under the direction of Health Secretary Robert F. Kennedy raises serious alarms. The methods and process lacked transparency, and several individuals with potentially meaningful conflicts of interest were involved in compiling the evidence.
Broadly speaking, guidelines contain recommendations to help their target audience, such as policy makers, clinicians and the public, make informed decisions.
The Food and Agriculture Organization of the United Nations defines national food-based dietary guidelines specifically as those that “provide context-specific advice and principles on healthy diets and lifestyles, which are rooted on sound evidence, and respond to a country’s public health and nutrition priorities, food production and consumption patterns, sociocultural influences, food composition data and accessibility, among other factors.”
Dietary guidelines can shape national policy, such as the Food Policy for Canada with initiatives like the National School Food Program. In the U.S., the new dietary guidelines have already been applied in changing the National School Lunch Program to allow whole milk.
In the past, guidelines were often made by a group of experts with little to no transparency about their decisions – an approach known in the guideline community as GOBSAT (“good old boys sitting around a table”).
Methods have since evolved, with standards and frameworks to reinforce rigour and curtail bias. Many guidelines, including dietary guidelines like Canada’s Dietary Guidelines, are underpinned by systematic reviews, which synthesize research evidence in a comprehensive way with quality assessments. Historically, systematic reviews were based on randomized controlled trials but can include other study types like observational designs – which have limitations yet are common for nutrition research.
Taking into account challenges with nutrition research and developing dietary guidelines, Health Canada updates its methods over time, known as an Evidence Review Cycle model, for our dietary guidelines.
The 2015 U.S. dietary guidelines were subject to political controversy including from the beef industry over its call to lower consumption of “red and processed meat,” prompting U.S. Congress to direct the USDA and HHS to overhaul the process in 2017.
A first step in the process is to form a scientific advisory committee known as the Dietary Guidelines Advisory Committee. The committee, comprising a group of vetted independent experts, released a scientific report in December 2024 that included evidence reviews intended to inform the guidelines. The HHS and USDA had “concerns” with this report, setting it aside and seeking to “further reform future DGA (Dietary Guidelines for Americans) development processes.” They cited “American public’s need for objective, evidence-based nutrition guidance.”
The revamped guidelines relied on additional, separate reviews of the evidence, a shift that has sparked confusion and apprehension from nutrition leaders and bodies like the American Society for Nutrition.
The document about the scientific foundation for the new guidelines asserted that this version includes “additional systematic reviews” on key topics with an emphasis on randomized controlled trials. Yet of the reviews in the 418-page appendices, seven were designated as narrative reviews, which do not rely on clearly defined methods, and two as umbrella reviews (reviews of existing systematic reviews).
This document designated the review of saturated fats as a systematic review, though later in the text it was specified as an umbrella review. One of the reviews on nutrient-dense protein foods (for weight management) was a rapid systematic review of randomized controlled trials, albeit without meta-analysis, deviating from what was in their protocol.
It is puzzling as to why the types of reviews differed by topic, given the scientific report stated that “a methodology expert established standardized protocols.” Three of the protocols for the reviews are findable in the systematic review registry PROSPERO. In contrast, all protocols for the systematic reviews informing the initial version of the scientific report are available on designated web pages and were posted for comment before the process started.
This leads to another question about transparency in terms of developing the U.S. dietary guidelines: how were decisions made for the guidelines based on these reviews and by whom? These questions are yet to be answered.
The process to develop Canada’s dietary guidelines and food guide involved consultations and discussions with key people and partners – as well as the public – and had two open consultations, giving space for anyone to weigh in. Health Canada did specific engagements with Indigenous partners. Conversely, the U.S. dietary guidelines explicitly sought to de-emphasize health equity.
In terms of who was not at the table, Health Canada officials in the Bureau of Healthy Eating Policy and Promotion did not have meetings with any food and beverage industry representatives during the process for the 2019 dietary guidelines.
Managing conflicts of interest is a basis for credible guidelines. But contributors to the additional reviews of the evidence for the U.S. dietary guidelines have disclosed financial ties to meat and dairy industries.
The ensuing recommendations in the U.S. dietary guidelines support higher protein intake, particularly from animal sources; Canada’s dietary guidelines from 2019 highlight plant-based protein foods.
The U.S. dietary guidelines, which have been widely covered in the Canadian news, may shape public perceptions here since one thing USDA and HHS have done effectively is sharing digestible information within a 10-page document, along with an inverted food pyramid.
However, the problem lies in how evidence has been selected, consolidated and translated into policy – and who was involved in these steps. This opaque process could lead to further erosion of trust in science, which is an ongoing struggle in the field of nutrition science.
