Dietary Guidelines Using Non-Systematic Process, Won’t Be “Trustworthy,” Experts Warn
Guidelines Have Excluded Majority of Rigorous Trial Evidence for Decades
New Review Says No Evidence for Current Recs on Fish Oils, Sat Fats, and more
Guidelines ARE Using Non-Systematic METHODS--Won’t Be “Trustworthy,” Experts Warn
USDA officials directing the Guidelines stated earlier this year that their scientific reviews would follow the “GRADE” system for evaluation of the science, GRADE is considered one of the top systems in the world for producing reliable scientific reviews and guidelines. However, in a recent public comment to the USDA, GRADE co-founder, Dr. Gordon Guyatt, expressed strong concerns that the USDA’s decision to “modify” GRADE would lead to Guidelines that are “unlikely to be trustworthy.” A principal problem, wrote Guyatt, is that the USDA has no methodology to distinguish between high- and low-quality evidence; “This distinction between high- and low-quality evidence lies at the core of any rigorous evaluation of science and is at the heart of the GRADE methodology,” stated Guyatt. A Distinguished Professor in the Department of Health Research Methods at McMasters University, he urged the USDA not even to use the word GRADE, “because doing so would give the appearance of rigor where it did not exist.”
OTHER Serious Questions About USDA’s Science Reviews
Another recent public comment to USDA, by Dr. Bradley Johnston, director of an independent group of international researchers who are leaders in high quality systematic reviews of nutrition science, stated that the USDA’s “proposed methodology…deviate[s] significantly from basic scientific precepts in a number of important ways. Taken together, these deviations…from international standards for systematic review methodology will result in a non-systematic approach that would seriously undermine the reliability of these reviews.”
Johnston, also a GRADE expert, stated that among other things, USDA’s decision to rely on its previous systematic reviews makes little sense, since USDA was cautioned by the National Academies of Sciences, Engineering, and Medicine (NASEM) that these earlier reviews used non-systematic approaches. “Thus, relying on these previous reviews would mean incorporating evidence that…is of questionable reliability,” wrote Johnston. He also questioned USDA’s use of “hand-searches” for science when the vast majority of scientific literature is online. Johnston concludes, “…based on the available documentation from CNPP[USDA], the proposed 2020-2025 U.S Dietary Guidelines for Americans will be fundamentally lacking in scientific rigor and will not comply with the upgrades in scientific methodology that NASEM has called for.”
These are serious issues, and we hope that USDA-HHS will make every effort to upgrade its scientific review process so that our Guidelines will be trustworthy and evidence-based.
TNC’s Nina Teicholz Tells Guidelines’ Committee of History of Excluded Evidence.
In oral testimony to the Dietary Guidelines Advisory Committee (DGAC) on July 11 in Washington, D.C., Teicholz emphasized that the Guidelines have, since their launch in 1980, excluded nearly all the rigorous, clinical-trial literature on nutrition and health. This ignored clinical-trial (“gold standard”) evidence was “funded mostly by governments around the world and included more than 75,000 people, in studies lasting up to 12 years,” stated Teicholz, citing her peer-reviewed 2015 article in The BMJ. The Nutrition Coalition has updated these numbers and now estimates that data from 136,780 people studied in clinical trials over a total of 139 years have been excluded. The cost of all the excluded studies is not available, but for a fraction of the studies (17), the cost of this research was $904,234,637, suggesting that the overall cost of excluded studies is likely to be in the billions of dollars. “Unfortunately, instead of informing our nation’s nutrition policy; this gold-standard evidence has been ignored.” said Teicholz.
Dietary Guidelines Committee Meeting Dominated by Industry, Vegetarian Advocates.
The July meeting of the Dietary Guidelines Advisory Committee was the second of five it will be holding as part of the process to review the science for the next set of Guidelines, due out in 2020. While all of these meetings are open to the public, only two—including this one--are inviting people to make oral comments. Typically, industry representatives dominate these events, and July’s meeting was no different, with about one third of commenters representing various food industries, ranging from whole grains to chewing gum. Their messages generally followed the line of ‘recommend more of my food group, please.’ Another one third or so of commenters came from non-profits or other groups advocating for vegetarian diets. A few argued that “dairy is racist,” because African Americans tend to have higher rates of lactose intolerance. Some, like the Physicians for Responsible Medicine, come with an animal-rights agenda, while others told their stories of health success on vegetarian diets. Most of these groups are long-timers at lobbying the Dietary Guidelines’ process. By contrast, a novelty this year was the appearance of about a dozen doctors from around the country calling for USDA to adopt a low-carbohydrate dietary pattern.” These doctors talked about how they could not help their patients when following the Guidelines yet reversed those failures upon adopting a real-foods, lower-carbohydrate approach.
For its part, the Guidelines Committee listened patiently, largely poker-faced, to more than three hours of comments.
If any of these issues are of concern to you, please consider making an oral to the committee at its January meeting in Houston, and/or submit a public comment to USDA. See our post on how to do this.
The Wild World of Nutrition Science
What Protects Against Heart Disease? No diets or supplements tried so far, according to an enormous new systematic review of various interventions to prevent heart disease. Nothing the researchers reviewed was supported by strong evidence for effective prevention. Not fish oils, not saturated-fat reduction, not the low-fat diet, not the Mediterranean diet, nor any supplement--including anti-oxidants, beta-carotene, selenium, or any Vitamin. Some of these interventions have been tested more than others. Diets low in fat and saturated fat as well as fish oil supplementation have all been tested in multiple large, long-term controlled clinical trials, and these have not shown 'positive' results. Thus, as this paper suggests, it’s fair to cross those off the list as effective interventions to prevent cardiovascular disease.
A “Review of Reviews” Paper on saturated fats finds that there are now 17 meta-analyses that have looked at the rigorous (clinical trial) literature on the question of whether saturated fats cause heart disease, and the authors conclude: “the results of most meta-analyses do not support the diet-heart hypothesis or the recommendation to replace saturated fat with polyunsaturated fat.” This ought to be another nail in the coffin of the “diet-heart hypothesis” (which holds that saturated fats cause heart disease), launched some 70 years ago by scientists at the University of Minnesota. Sadly, there’s currently very little chance that the next Dietary Guidelines will effectively re-examine its caps on saturated fats, because USDA staff has decided not to look at any outside review papers, like this one or any of the 17 meta-analyses it cites. Plus, the original trial data is now outside the date range of USDA’s scientific reviews. All those data were excluded/ignored, as Teicholz noted in her oral comments, and there seems to be no mechanism for revisiting them.
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The Nutrition Coalition is a nonprofit educational organization working to strengthen national nutrition policy so that it is founded upon a comprehensive body of conclusive science, and where that science is absent, to encourage additional research. We accept no money from any interested industry.
Annual Giving: It’s that time of year for many people who are planning end-of-year gifts. Please consider supporting The Nutrition Coalition! We are the only group anywhere in the world working to instill scientific rigor in nutrition guidelines. Because we accept no industry support, we rely on the generosity of people like you to support our mission, purely in the interest of the public health. Thank you!
