Dietary Guidelines are Unscientific, Outdated
New Paper in Nat'l Academies of Sciences' Journal finds Major Flaws
By, Nina Teicholz
Why do kids in public schools get served donuts and orange juice for breakfast, a meal guaranteed to send blood sugars soaring, rather than a sugar-free, protein-rich option, like scrambled eggs? The unfortunate answer is that the donut meal accords with our nation’s top nutrition policy, the U.S. Dietary Guidelines for Americans, which despite its influence has been found by a new study to contain outdated science and not reflect the “preponderance of scientific and medical knowledge,” as required by law.
These and other disquieting findings are the subject of a paper I co-authored, published in a journal of the nation’s highest scientific body, the National Academies of Sciences, Engineering, and Medicine. To my knowledge, it is the most comprehensive critique of the Dietary Guidelines to date, written by top experts who include three former members of the very expert committees (called the Dietary Guidelines Advisory Committee, or DGAC) that reviewed the science for past versions of the guidelines. Yet now, they view this policy as flawed.
In plain terms, we found that the U.S. guidelines—despite being followed by all federal agencies and most schools, hospitals, doctors and dieticians— cannot be guaranteed to reflect trustworthy advice for the urgent task of combating obesity, diabetes or any other chronic disease.
This post is wonky but relevant to people interested in good policy or how food policy affects their children, parents, schools, communities, and more.
This post may also interest anyone who believes a diet “rich in fruits, vegetables, legumes, cereals/whole grains, nuts, fish, and unsaturated [vegetable] oils and low in meat and high-fat dairy” is the key to better health—because that’s exactly the diet at the heart of the guidelines.
Criticism of the evidence underpinning this dietary advice goes back decades. A report in 1980 by the National Academies of Sciences that examined the foundational studies for the Guidelines concluded that the proposed diet had “generally unimpressive results,” and the director of the National Heart, Lung and Blood Institute urged restraint, noting a lack of scientific evidence for the guideline recommendations and the potential for unintended consequences.1
More recently, a former DGAC member wrote:
“Despite our evidence-based review lens where we say that food policies are ‘science based,’ in reality we often let our personal biases override the scientific evidence.”
In 2017, the National Academies of Sciences, Engineering, and Medicine (NASEM) weighed in with two reports, at the behest of Congress. The NASEM found that the guidelines process needed to “improve transparency” and “strengthen scientific rigor.”
"To develop a trustworthy DGA,” the report states, “the process needs to be redesigned.”
The NASEM issued 7 recommendations, yet five years later, six of these had not been implemented in full, and the seventh could not be verified due to lack of information, according to a follow-up NASEM report published this year. The USDA has resisted reforming even the most glaring problems, such as the lack of public disclosure of conflicts of interest on the DGAC committee, when such disclosures on guidelines committees are now the norm. (Fully 95% of members on the 2020 DGAC were found to have at least one tie to industry, and a majority had 20 such relationships or more.)
In line with the NASEM, our paper found a number of serious problems with the guidelines process. And on key topics—including dietary fat, saturated fat, and cholesterol—we concluded that the guidelines are no longer supported by the science, or are simply in error.
Major findings of our paper.
Outdated Science
The law requires that the science underpinning the current guidelines be “current at the time the report [was] prepared,” but this was not the case with the most recent guidelines report, out in 2020:
The scientific reviews for the “Dietary Patterns” (the main dietary advice, i.e., the list of foods above) included studies only through 2012-2013, i.e., 8-to-9 years out-of-date at the time of the report’s publication.
The reviews for the “Birth-to-24 Months” recommendations included science only through mid-July 2016, which was at least 4 years out-of-date at the time of the 2020 report.
To finish reading, please click here to read the article on my “Unsettled Science” Substack.