In 2019, Annals of Internal Medicine published a series of reviews and a set of guidelines that argued there was insufficient evidence to link meat consumption to heart disease, cancer, or overall mortality and, consequently, insufficient evidence to support prior recommendations to reduce meat intake (1). This recent JAMA piece reviews the responses from supporters and detractors of the controversial series and guidelines, providing insight into a dramatic behind-the-scenes scramble to preserve the dominance of the anti-meat scientific consensus.
The Annals papers, published in November 2019, evaluated research from observational studies and controlled trials investigating the relationship between meat intake and disease. They applied the GRADE methodology to this data, which places greater weight on evidence derived from controlled trials than observational data. The group found a small but uncertain association between increased meat intake and ill health in the epidemiological data, but no link between meat and cancer, heart disease, or death from any cause from 12 randomized controlled trials enrolling 54,000 total participants. They consequently concluded there was insufficient evidence to discourage meat consumption. An accompanying letter summarized these points.
Just before publication, Christine Laine, editor-in-chief of the journal, received around 2,000 emails, many of which were clearly the result of an automated script. She noted the tone of the emails was “particularly caustic” and even more vitriolic than the response the journal had previously received from the NRA after publishing research on firearm injury prevention.
This email response was coordinated by True Health Initiative (THI), a nonprofit led by David Katz, whose team includes Dr. Walter Willett, a faculty member in the Harvard School of Public Health who has been described as “the world’s most influential nutritionist.” THI members received the articles five days prior to their publication; by the next day, Katz and 11 other THI members sent a letter to Laine asking for the preemptive retraction of the paper. Signatories included Willett, his Harvard colleague Frank Hu, and former Surgeon General Richard Carmona. According to Annals media relations manager Angela Collom, this response represented a violation of the journal’s embargo policy; Katz was subsequently dropped from the list of individuals receiving advanced access to articles.
Katz later described the articles as “a great debacle to public health” and likened the recommendations to terrorism. Another signatory, Neil Barnard, filed for the City of Philadelphia and the FTC (in two separate petitions) to block the publication of the reviews, citing them as a public danger. Later, at a cardiology conference, Willett presented a slide representing the journal, Dr. Gordon Guyatt (who chaired the panel that created the guidelines and was a contributing author to the reviews), and New York Times reporter Gina Kolata (who first reported on the papers) as sources of “disinformation.”
Soon after the guidelines were published, the Harvard School of Public Health posted a response, arguing the use of the GRADE methodology was “problematic” and the guidelines should not change previous recommendations against meat consumption.
Katz has criticized the use of GRADE in nutrition research, arguing the use of randomized controlled trials to study nutrition is infeasible. He and Willett have proposed an alternative review methodology, HEALM, which allows scientific conclusions to be more easily drawn directly from epidemiological research. Katz describes himself as “not anti meat … just pro-science,” despite his promotion of what many would argue is a weaker or even un-scientific experiment design for nutrition research.
Guyatt described the negative response to the Annals series and guidelines as both “predictable” and “hysterical.”
The New York Times and others reported that Bradley Johnston, lead author of the guidelines, had failed to disclose receiving funding from the International Life Sciences Institute (ILSI), an organization CrossFit has been strongly critical of in the past and which receives heavy industry funding. Johnston argued this disclosure was not required, as the funding was outside the three-year disclosure reporting period required by Annals; in The New York Times piece, he described his decision to take ILSI funding as “naive.” Other members of the group had additional conflicts, including John Sievenpiper (ILSI) and Patrick Stover, who, like Johnston, had received funding from Texas A&M AgriLife, which receives a small amount of funding — about 1.5% of total income — from the cattle industry.
Katz’s organization has received support from organizations advocating for plant-based diets, the olive industry, the nut industry, and multiple food industry companies. Katz himself has received industry funding from a wide variety of sources. The Chan School of Public Health at Harvard, Willett and Hu’s home institution, has also received funding from the walnut industry (2). Carmona serves on the board of Herbalife. With convenient equanimity, Katz has described these industry ties as a “confluence of interest” rather than a conflict.
The Annals series and other relevant references are briefly summarized below.
These guidelines, published in November 2019 and accompanied by five reviews in the same issue, conclude there is insufficient evidence to discourage meat consumption on the basis of health.
This editorial, which accompanied the above guidelines, recognizes its conclusions are at odds with previous research while reinforcing its primary thrust: that any statistically significant links between increased meat intake and disease are entirely derived from observational evidence and are, for this and other reasons, “low certainty” and insufficient to justify public guidelines or behavioral changes.
The BMJ initially reports on undisclosed conflicts of interest among the authors of the Annals guidelines, particularly funding by ILSI to Johnston in support of a paper (also using GRADE) finding “low certainty” evidence to support guidelines to restrict sugar intake. Frank Hu is also quoted arguing against the use of GRADE in nutrition science, as the application of GRADE would undermine previous recommendations derived from observational evidence such as that linking secondhand smoke, air pollution, and trans fats to ill health.
The New York Times also reports on conflicts of interest among the Annals authors. Johnston argues he was “naive” and did not understand the extent to which ILSI was funded by industry. Hu here again expresses concerns about “the damage that has already been done to public health recommendations.”
The GRADE framework aims to assign a certainty rating to any observed effect based on “a reproducible and transparent framework.” Certainty is decreased by risk of bias, imprecision, inconsistency, indirectness, and publication bias; it is increased by large magnitude of effect, a clear dose-response gradient, and any residual confounding that would decrease, not increase, the magnitude of effect if theoretically removed.
This HEALM methodology, developed by a team including Katz and Willett, seeks to develop recommendations and guidelines in the absence of data from controlled trials.
Dr. David Ludwig and others note consistent issues with the quality of dietary research, highlighting challenges related to the funding environment, study design, and execution. They claim it is a field that favors a few specific dietary patterns at the expense of others.
John Ioannidis argues nutrition epidemiology has been used to justify ridiculous assertions, such as the argument that eating 12 hazelnuts each day would prolong life by 12 years. Such relationships are frequently described as causal and are highly influential on guidelines and public health despite substantial errors in the interpretation of the studies, which make it “challenging, if not impossible” to identify the role of any single dietary component on health outcomes. Ioannidis also notes such observations have consistently failed to replicate when subsequently tested in controlled trials.
The Harvard School of Public Health criticizes the Annals guidelines, arguing they are “not justified” and that the use of the GRADE methodology, as well as their decision to ignore environmental considerations, is “problematic.” It argues these recommendations undermine the public health benefits achieved by previous analyses that encourage a reduction in meat intake.
True Health Initiative describes how it “rapidly mobilized” in response to the Annals piece. Multiple quoted parties describe the guidelines as “dangerous,” and Willet describes them as “the most egregious abuse of data I’ve ever seen.”
This letter to the editor, sent by THI members to the editor-in-chief of Annals, requests preemptive retraction of the guidelines on the basis of “grave concerns about the potential for damage to public understanding, and public health.”
The Physicians Committee for Responsible Medicine, led by Neil Barnard, filed a request for an investigation by the Philadelphia Office of the District Attorney (which holds jurisdiction over Annals) of “potential reckless endangerment” due to the dissemination of the Annals papers.
Neil Barnard, President of the Physicians Committee for Responsible Medicine (PCRM), filed an FTC petition to correct alleged false statements made within the Annals guidelines. PCRM requests that the FTC “permanently prohibit AIM from disseminating, or causing the dissemination of, the advertisement at issue and require AIM to issue a public retraction of and corrective statement regarding the advertisement” on the basis of promoting physical and financial harm.
Katz describes the Annals papers as a debacle and likens them to terrorism (arguing they fits the definition of “the systematic use of terror especially as a means of coercion”). He argues the damage caused by researchers who undermine the established links between meat and ill health are creating damage “massively more lethal” than traditional forms of terrorism.
This slide, presented by Willett at a cardiology conference not long after the Annals guidelines were published, characterizes the journal, Kolata at The New York Times (who reported on its findings), Guyatt (who developed GRADE and coined the term “evidence-based medicine”), and Stover of Texas A&M as sources of “disinformation.”
Guyatt, commenting on the response to the Annals piece, argues the direction of the backlash is predictable but in its severity “hysterical.” He interprets the group’s findings as arguing that cutting back meat “wouldn’t be worth it for people who really enjoy meat.” He characterizes those arguing against meat as taking “a pretty extreme stance” that treats uncertain assumptions in a way that fails to take into account the uncertainty inherent in health.
Katz argues not all industry conflicts of interest are problematic. He argues some conflicts merely represent a “confluence of interest” in which a researcher’s interests naturally align with those of a private entity; so long as the researcher demonstrated this interest prior to establishing the conflict, Katz is unperturbed by such partnerships.
- Red and processed meat consumption and risk for all-cause mortality and cardiometabolic outcomes: A systematic review and meta-analysis of cohort studies; Reduction of red and processed meat intake and cancer mortality and incidence: A systematic review and meta-analysis of cohort studies; Effect of lower versus higher red meat intake on cardiometabolic and cancer outcomes: A systematic review of randomized trials; Patterns of red and processed meat consumption and risk for cardiometabolic and cancer outcomes: A systematic review and meta-analysis of cohort studies; Unprocessed red meat and processed meat consumption: Dietary guideline recommendations from the Nutritional Recommendations (NutriRECS) Consortium
- Hu has published research specifically arguing for the benefits of walnut consumption.