Modern Scientific Controversies Part 7: The Meat War

Guest Essay by Kip Hansen  —  10  October 2019

 

The_Meat_WarThe_Meat_WarPrologue:  This is part of  an occasional  series of essays that discusses ongoing scientific controversies, a specific type of which are often referred to in the science press and elsewhere as “Wars” – for instance, one essay covered the “Salt Wars1 and another the “Obesity War” — and one which appears most commonly here at this web site: “The Climate Wars”.    The purpose of the series is to illuminate the similarities and differences involved in these ongoing controversies, as part of the social culture of science in our modern world.

This essay specifically covers the furor over a six-paper body of work that appeared recently in The Annals of Internal Medicine reviewing the evidence used to make public health recommendations for amounts of red and processed meat in the human diet.

In The Meat War, the headlines scream out:

Uproar after research claims red meat poses no health risk  — The Guardian

Should you keep eating red meat? Controversial study says well-known health risks are just bad science — USA Today

Meat’s Bad for You! No, It’s Not! How Experts See Different Things in the Data — NY Times

New “guidelines” say continue red meat consumption habits, but recommendations contradict evidence — The Nutrition Source at Harvard

Scientist Who Discredited Meat Guidelines Didn’t Report Past Food Industry Ties — NY Times

Only one of these headlines is strictly true — the others are all distortions of what the published studies found and what they mean for public health guidelines.  [ Ten Critical Thinking Skills points to the first reader to correctly identify the one that is true. ] This should not surprise you — headlines are written to grab your attention so that you will read the story underneath.  Headlines can  bias the reader before they see a single fact.

What is all this hub-bub about?

Nurtirecs2Nurtirecs2A group of nutritional scientists and doctors, associated in an organization called NutriRECS,  spent three years looking at public health recommendations on  meat consumption, the kind  which most often appear as diet recommendations like those  pictured below.   Their efforts resulted in a suite of six papers, all published simultaneously in the 1 October 2019 edition of The Annals of Internal Medicine.

food_guidelines_chan_ukfood_guidelines_chan_uk

“NutriRECS is an independent group with clinical, nutritional and public health content expertise, skilled in the methodology of systematic reviews and practice guidelines who are unencumbered by institutional constraints and conflicts of interest, aiming to produce trustworthy nutritional guideline recommendations based on the values, attitudes and preferences of patients and community members.” — says the NutriRECS About page.  They produce “Nutritional Recommendations and accessible Evidence summaries Composed of Systematic reviews” (thus NutiiRECS). — NutriRECS

Who exactly are they?  A bunch of nutrition-skeptic troublemakers?  No, they are well-respected doctors and scientists from many different countries and institutions:

[ Readers may skip this section, it is included to illustrate that these papers have been written by a large team of doctors and specialists. ]

LEADERSHIP TEAM:

Dr. Bradley Johnston — director and co-founder of NutriRECS, and is an Associate Professor with the Department of Community Health & Epidemiology, Faculty of Medicine, Dalhousie University, Halifax, Canada.

Dr. Pablo Alonso-Coello — co-founder of NutriRECS, the head of the Barcelona GRADE center, and is a health services researcher at the Biomedical Research Institute (Hospital Sant Pau) in Barcelona, Spain.

Dr. Malgorzata (Gosia) Bala — co-founder of NutriRECS, the head of the Cochrane Poland, and the chair of Epidemiology and Preventive Medicine at the Jagiellonian University Medical College, Cracow, Poland.

Dr. Gordon Guyatt — coined the term “evidence-based medicine”, is a mentor, Clinician-Scientist and Distinguished Professor in the Department of Health Research Methods at McMaster University, Hamilton, Canada.

Catherine Marshall —  a Cochrane Consumer located in Wellington, New Zealand.   https://ift.tt/2B0MZ24

Dr. Patrick Stover — Vice Chancellor and Dean of Agriculture and Life Sciences at the Texas A&M University System.

COLLABORATING TEAM

Dr. Per Vandvik —  Associate Professor in the Department of Health Management and Health Economics, University of Oslo, Norway

Dr. George Kephart —  Professor, Department of Community Health and Epidemiology, Faculty of Medicine, Dalhousie University. He is co-founder and former Director of Health Data Nova Scotia.

Dr. Regina El Dib — Assistant Professor at the Institute of Science and Technology, Estadual Paulista University, Brazil, and founder and director of the systematic review unit of the Botucatu Medical School.

Dr. Russell de Souza —  registered dietitian and nutrition epidemiologist.

Dr. Celeste Naude —  registered dietician at the Centre for Evidence-based Health Care at Stellenbosch University, South Africa; and Co-Director of Cochrane Nutrition.

Dr. Lehana Thabane  —   Professor of Biostatistics and Associate Chair of the Department of Health Research Methods, Evidence, and Impact at McMaster University, Hamilton, Canada. He is also the Director of Biostatistics at St Joseph’s Healthcare in Hamilton.

Dr. Mi Ah Han —  professor in the Department of Preventive Medicine, Chosun University, Republic of Korea. She is a visiting professor with Department of Health Research Methods, Evidence, and Impact in Hamilton, Canada.

Their work, however,  extends far beyond the bounds of nutritional recommendations.

What were their published findings about meat?

Red and Processed Meat Consumption and Risk for All-Cause Mortality and Cardiometabolic Outcomes: A Systematic Review and Meta-analysis of Cohort Studies

Conclusion:   The magnitude of association between red and processed meat consumption and all-cause mortality and adverse cardiometabolic outcomes is very small, and the evidence is of low certainty.

Reduction of Red and Processed Meat Intake and Cancer Mortality and Incidence: A Systematic Review and Meta-analysis of Cohort Studies

Conclusion:   The possible absolute effects of red and processed meat consumption on cancer mortality and incidence are very small, and the certainty of evidence is low to very low.

Patterns of Red and Processed Meat Consumption and Risk for Cardiometabolic and Cancer Outcomes: A Systematic Review and Meta-analysis of Cohort Studies

Conclusion:   Low- or very-low-certainty evidence suggests that dietary patterns with less red and processed meat intake may result in very small reductions in adverse cardiometabolic and cancer outcomes.

Effect of Lower Versus Higher Red Meat Intake on Cardiometabolic and Cancer Outcomes: A Systematic Review of Randomized Trials

Conclusion:   Low- to very-low-certainty evidence suggests that diets restricted in red meat may have little or no effect on major cardiometabolic outcomes and cancer mortality and incidence.

Health-Related Values and Preferences Regarding Meat Consumption: A Mixed-Methods Systematic Review

Conclusion:   Low-certainty evidence suggests that omnivores are attached to meat and are unwilling to change this behavior when faced with potentially undesirable health effects.

Unprocessed Red Meat and Processed Meat Consumption: Dietary Guideline Recommendations From the Nutritional Recommendations (NutriRECS) Consortium

Recommendations:   The panel suggests that adults continue current unprocessed red meat consumption (weak recommendation, low-certainty evidence). Similarly, the panel suggests adults continue current processed meat consumption (weak recommendation, low-certainty evidence).

How have these results been received?

 “The American Heart Association, the American Cancer Society, the Harvard T.H. Chan School of Public Health and other groups have savaged the findings and the journal that published them.”  —  Gina Kolata in the NY Times

Kolata’s description of the reaction could not be more accurate — the attacks on the papers, the journal, and the authors have been just that: savage , as defined as   “lacking the restraints normal to civilized human beings”.  Kolata’s linked article in the NY Times  is sensible, well-rounded, fair and among the most informative of the coverage in the mass media.  Kudos to her.

[ Note that “the journal that published” the studies is  Annals of Internal Medicine which is widely recognized as “one of the most widely cited and influential specialty medical journals in the world” and is published  by the American College of Physicians (ACP) which is the largest medical-specialty organization and second-largest physician group in the United States, after the American Medical Association.  It has 154,000 members. ]

Gina Kolata’s  colleagues at the Health Desk of the NY Times, Tara Parker-Pope and Anahad O’Connor,  were not so restrained:  Scientist Who Discredited Meat Guidelines Didn’t Report Past Food Industry Ties.  They repeat the attacks on one of the authors, Bradley C. Johnston, who has in the past received research funding from “a powerful industry trade group” [ILSI ].  The point is vaguely true, but is a niggle, as the Times’ report admits: : “Although the ILSI-funded study publication falls within the three-year window, he said the money from ILSI arrived in 2015, and he was not required to report it for the meat study disclosure. ‘That money was from 2015 so it was outside of the three year period for disclosing competing interests,’ said Dr. Johnston. ‘I have no [current] relationship with them whatsoever.’”  Continuing, the Times reports that “Dr. Laine  [editor in chief of the Annals of Internal Medicine] noted that people on both sides of the meat issue have conflicts of interest. ‘Many of the people who are criticizing these articles have lots of conflicts of interest they aren’t talking about,’ she said. ‘They do workshops on plant-based diets, do retreats on wellness and write books on plant-based diets. There are conflicts on both sides.’”

[ Note that the ILSI — International Life Sciences Institute  — has been under attack recently on the Health pages of the NY Times  and has responded in their own defence. ]

And in that, Dr. Laine is absolutely right.

Physicians Committee for Responsible Medicine, a group advocating a plant-based diet, [ their web site states that their mission is “dedicated to saving and improving human and animal lives through plant-based diets and ethical and effective scientific research” — kh  ]  on Wednesday filed a petition against the journal with the Federal Trade Commission. Dr. Frank Sacks, past chair of the American Heart Association’s nutrition committee, called the research “fatally flawed.” “ —  NY Times 

 [ The petition is a publicity stunt — the Federal Trade Commission has no authority over journals publishing scientific results — thank heavens! — the FTC can and does regulate advertising.  ]

The most radical attacks come from Dr. Frank Hu, Chair of the Department of Nutrition, Harvard T.H. Chan School of Public Health.  The Chan School is a major proponent of plant-based diets and publicly advocates the inclusion of reductions (or elimination) of red meat consumption in public health dietary guidelines.  Hu is one of the signatories of a letter issued by the True Health Initiative, an advocacy group pushing “lifestyle health solutions” and mostly-plant-based diets,  to Annals of Internal Medicine, recommending that they preemptively retract publication of these papers on the basis of grave concerns about the potential for damage to public understanding, and public health.

In addition to Harvard T.H. Chan School of Public Health’s own critique of the NutriRECS papers,  Hu is quoted in nearly every media article attacking the studies:

Hu said. “But they misuse the data from the Woman’s Health Initiative to say that meat reduction has no effect on cardiovascular disease, cancer or mortality.”

[ This statement is false:  the NutriRECs team did not say that at all.  See the conclusions of the studies earlier in this essay. ]

“But Dr. Hu said Dr. Johnston’s methods were not very objective or rigorous and the tool he employed in his meat and sugar studies could be misused to discredit all sorts of well-established public health warnings, like the link between secondhand smoke and heart disease, air pollution and health problems, physical inactivity and chronic disease, and trans fats and heart disease.”  “Some people may be wondering what his next target will be,” Dr. Hu said. “But I’m concerned about the damage that has already been done to public health recommendations.”– NY Times

[ The “tool” referred to above is the GRADE methodology for “Grading of Recommendations Assessment, Development and Evaluation” and has been in development and use for over a decade.  It is featured in a series of articles in BMJ (previously titled the British Medical Journal) here, here, here and here.  It is specifically designed to grade recommendations — such as clinical and public health guidelines. ]

Irresponsible and unethical,” said Dr. Hu, of Harvard, in a commentary published online with his colleagues. Studies of red meat as a health hazard may have been problematic, he said, but the consistency of the conclusions over years gives them credibility.  Nutrition studies, he added, should not be held to the same rigid standards as studies of experimental drugs.” — NY Times

 Nothing new is coming out of the study,” said Dr. Frank Hu, chairman of the Department of Nutrition at Harvard T.H. Chan School of Public Health. “There was no breakthrough. It just confirmed previous findings.” —  USA Today

“Hu, of Harvard, acknowledged the limitations with observational studies – they don’t show causation because a variety of compounding factors like a person’s lifestyle or other dietary choices could be causing the adverse health effects.  … However, when nutrition data is replicated across demographics, age and geography – as was the case with the more than 6 million participants from more than 100 large studies in the Annals’ analyses – it should be taken seriously, Hu said.”  —  USA Today

“The panel’s blanket recommendation that adults should continue their red meat consumption habits is highly irresponsible. We are facing a growing epidemic of diet-related chronic diseases and a climate change crisis, both of which are linked to high meat consumption,” Frank Hu, Chair of the Department of Nutrition, Harvard.”  —  True Health Initiative

“If the same procedure were used to validate secondhand smoking, for example, the evidence would be rated very low or low quality.”  – Dr. Frank Hu, chair of the nutrition, Harvard T.H. Chan School of Public Health — PBS

[ “Notably, secondhand smoke, the smoke inhaled from tobacco smoked by other people, creates about as much as risk for cancer and heart disease as red and processed meat — and the underlying studies around secondhand smoke carry just as much uncertainty.” — PBS ]

“That really doesn’t make any sense, right? The most important criteria in science is reproducibility and replication,” Hu said. — PBS

[ Hu is dissembling here — what he is saying is that there are a lot of studies that each find the same small-scale associations (correlations) and mis-identifies that as “reproducibility and replication”.  But, these are cohort diet-recall studies, and thus, according to John Ioannidis:   “These implausible estimates of benefits or risks associated with diet probably reflect almost exclusively the magnitude of the cumulative biases in this type of research, with extensive residual confounding and selective reporting.” ]

And from Hu’s Harvard T.H. Chan School of Public Health’s editorial on the studies [maybe written by Hu..]:  “To improve both human health and environmental sustainability, it is important to adopt dietary patterns that are high in healthy plant-based foods and relatively low in red and processed meats.” …. “The panel declared ‘considerations of environmental impact’ out of the scope of their recommendations.     This is a missed opportunity because climate change and environmental degradation have serious effects on human health, and thus is important to consider when making recommendations on diet, even if this is addressed separately from direct effects on individual health.” — source

Of course, Frank Hu is not the only major league doctor in the nutrition field to stage an attack.  One of the oddest attacks comes from Christopher Gardner, a professor at the Stanford Prevention Research Center:

“The new studies also only consider the direct impact of eating meat on someone’s body, which is not the only way meat can affect health: Meat production, particularly beef production, is a major contributor to greenhouse gas emissions and global climate change. Emissions and the changing climate are, in turn, major public health threats. So even if eating meat won’t directly cause heart disease in an individual, breathing in air polluted by meat production can. That’s critical to consider when making dietary recommendations, Gardner says.” —   PopSci.com

[ Breathing air “polluted by meat production” can cause heart disease?  That’s bit beyond….  I have emailed Dr. Gardner to ask if he has been quoted correctly, but his mail server auto-responds that he is on sabbatical for the rest of the year.  — kh ]

Why this savage response?

 “ ‘Dr. Johnston said the real problem is that people don’t want to accept findings that contradict long-held views. “People have very strong opinions,” he said. “Scientists should have intellectual curiosity and be open to challenges to their data. Science is about debate, not about digging your heels in.’ “ —  NY Times

Aaron Carroll, long-time science and medicine columnist for the NY Times , wrote an editorial that accompanied the NutriRECs studies in the Annuals of Intern Medicine, lays out the opposing sides in his column in the NY Times

yellow_boxyellow_box

 Expert Judgement and  Evaluation

 We see that this Science War, the Meat Wars, is typical and could be used as a exemplar for the general class.   We have an “establishment” tribe — a group that has controlled the research and imbued the field with their own shared scientific point of view (which could just be the cumulative bias in the field).  This establishment group (individuals, associations, university departments, etc) jealously guards the scientific field and their scientific viewpoint from other viewpoints that might threaten their position of prestige and power.  This is perfectly normal for most endeavors.

These types of controversies only become Science Wars when at least one of the “tribal sides” shifts from simply defending their viewpoint  (their ideas, their recommendations)   with collegial rational discussion and good science to savage attacks on those that might have other opinions that challenge the status quo in the field — attacks on the science, on the persons, on the journals — extending even to efforts to prevent publication (as in the Meat Wars), calling for retraction (several Wars), even personal law suits.

We have seen this in Climate Science in spades.  In the Salt Wars, two bodies of researchers  publish  opposing studies in the journals and establishment groups (like the American Heart Association) denigrate all contrary findings.   In the War on Sugar we have a broad common bias against sugar in nearly all establishment groups in the field of nutrition who fight tooth-and-nail any science findings that do not condemn added sugars in the human diet.  (One of the players in the Meat Wars, Brad Johnston, was a player in the War on Sugar, when he published a industry-funded study on sugar.)

Recently, John P. A. Ioannidis took Nutritional Epidemiology, the basis for recommendation on human diet, to task in a major journal article titled “The Challenge of Reforming Nutritional Epidemiologic Research”  ( I wrote about it here).  His elicited comment on the Meat Wars:

“I would not run any more observational studies,” said Dr. John Ioannidis, a Stanford professor who studies health research and policy. “We have had enough of them. It is extremely unlikely that we are missing a large signal,” referring to a large effect of any particular dietary change on health.”  —  NY Times

 One last quote from another cool-head in the overheated debate:

“Dr. Meir Stampfer, also of the Harvard T.H. Chan School of Public Health. He believes that the data in favor of eating less meat, although imperfect, indicate there are likely to be health benefits. “ . . . .  “Dr. Dennis Bier of Baylor said the studies of meat consumption are so flawed that it is naïve to assume these risk reductions are caused by eating less meat.”   Or maybe, said Dr. Bier, policymakers should try something more straightforward: “When you don’t have the highest-quality evidence, the correct conclusion is ‘maybe.’”  — NY Times (and here)

Bottom Lines and Take-aways:

    1. Honest, well-meaning serious scientists can look at the exact same body of evidence and come to different conclusions, in any field of study.  It is this aspect of science that leads to advances when the scientists act professionally and attempt to use that difference of opinion to further better understanding in their field.  On the other hand, when scientists dig in, take tribal positions and sling calumny and accusations over differences in scientific opinions, they prevent good science from advancing and damage the reputation and public perception of science.
    2. If evidence for a claim or recommendation is scientifically weak there will be more controversy — and there should be. Definitive claims and public policy should not be made on evidence which is acknowledged to be weak or only associational.   We have to learn to be able to say “We don’t really know”  and “There just isn’t enough solid evidence to say…”.   We have to learn to accept “maybe” as the best answer science has to offer at this time.
    3. The problem in the Meat Wars, like many other Science Wars, is that public policy has been set based on weak, iffy, dodgy, associational, hypothetical and otherwise scientifically unreliable evidence.  Those responsible for recommending those public policies react badly when this fact is pointed out.  After all, they cannot rely on the strength of the evidence behind their recommendations to defend themselves.
    4. Human Nutritional Science has been captured by advocates of all sorts of unsupportable ideas based on the current practices of Nutritional Epidemiology, which Ioannidis has pointed out is “intrinsically unreliable”.

    # # # # #

    Author’s Comment:

    Most of my opinions about this topic are contained in my earlier essay on Nutritional Epidemiology.

    In the spirit of Full Disclosure:   my family and I adhere to a religious health code that calls for eating meat sparingly.

    It is my opinion that far too many public policies are based not on solid oak timbers of evidence but on matchstick thin evidence — a fact which is causing a great many problems in society at large.

    The very existence of these Science Wars offends me deeply — as they damage the reputation of Science and prevent Science — our knowledge base about the physical world around us — from advancing and expanding.

    Begin your comments with “Kip..” if speaking to me personally.  If speaking to some other specific commenter, begin with their name/handle, it helps to keep the conversations clear.

    # # # # #

     

via Watts Up With That?

https://ift.tt/2M1XXea

October 10, 2019 at 08:52AM

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