Blog | Tuesday, January 10, 2017

Bullet holes in dietary guidance


In case you missed it, the Center for Science in the Public Interest, with a long and illustrious history of doing just what their name implies, issued a statement that the once prestigious British Medical Journal (BMJ) had stained its reputation by perpetuating support for a discredited opinion piece attacking the work, and report, of the 2015 Dietary Guidelines Advisory Committee here in the U.S.

This is a scene, and perhaps not the final one, in a long-running saga, so a brief overview of the drama up until now is likely in order.

The official report of the 2015 Dietary Guidelines Advisory Committee, constituting the science and expert opinion intended to guide the development of the official Dietary Guidelines for Americans, was submitted as required to the Secretaries of the U.S. Departments of Health and Human Services (HHS) and Agriculture (USDA), in February 2015.

Any ink involved had not yet dried before this report was erroneously assaulted in the New York Times as “the government's bad diet advice.” Leaving aside the fact that a who's who in the world of nutrition and public health thinks this report excellent rather than bad (and I concur), it is, quite simply, not the government's advice. The DGAC report is, in fact, advice to the government about what the official dietary guidelines should be. This, too, was in February 2015.

Around that same time, Politico reported that the beef industry was planning robust opposition to the DGAC recommendation that the Dietary Guidelines address sustainability, and in the service of it as well as health, clearly advise the American public to reduce meat consumption.

The BMJ got involved in September 2015, when they published an expanded version of the very opinion piece published months earlier in the New York Times, calling it an investigative article. Early in October 2015, responding to these rather inexplicably prominent assaults on mainstream nutrition science by a journalist with no known relevant expertise and a book to sell into the bargain, Politico once again weighed in, disclosing links between an effective publicity campaign and deep pockets affiliated with the beef and fossil fuel industries.

Then, in November 2015, the Center for Science in the Public Interest submitted a letter to the BMJ, signed by 180 scientists from 19 countries, calling on the journal to retract the critique of the DGAC report, laying out in detail the inaccuracies, and pointing out the rather prominent conflict of interest involved. Later that same month, the BMJ editorial office indicated they would have the matter reviewed-and all concerned have been waiting ever since. In the interim, the official Dietary Guidelines for Americans, a very disappointing relative to the DGAC report, was published in January 2016. It was disappointing in part because the mischief recounted above worked as intended. Lobbying by special interests altered the key messages, and expunged the attention to sustainability altogether.

Which brings us to December 2016, when the BMJ announced completion of its independent review of the matter, indicating that they would not retract the critique. The journal published both “corrections” and “clarifications” of the critique, appended to corrections made earlier in the process. Responding to this outcome, and the positive public relations spin circulated on behalf of both the journal and the critique author, CSPI made its public allegation about a stained reputation.

The BMJ ”review” was conducted on the journal's behalf by two independent experts, Dr. Mark Helfand of Oregon Health and Science University, and Professor Lisa Bero of the University of Sydney. I have read both of their reports. Prof. Bero's report was submitted to the BMJ nearly a year ago, on Dec. 11, 2015. Dr. Helfand's report is not dated, so we are left not knowing whether its delivery, hand wringing at the BMJ editorial office, or something else- accounts for the delay of many months.

The selection of these two particular experts is very interesting. With all due respect to them both, and I think they are both quite deserving of plenty, neither has established expertise in nutrition. Both are experts in methods of evidence review. In terms of content, Dr. Helfand has noted expertise in hospital medicine and clinical decisions, and Prof. Bero in pharmacology.

Having devoted years to writing textbooks about methods of epidemiologic research, and the statistical underpinnings of clinical decisions, and additional time conducting meta-analyses of my own, I fully appreciate the methodologic expertise of Drs. Bero and Helfand. That said, inattention to content expertise in nutrition is a profound deficiency in this review.

Consider, by way of analogy, the case of fighting fires, or treating gunshot wounds. An expert in the methodology of “evidence” would be forced to conclude that the evidence justifying either current means of fighting fires, or treating gunshot wounds, is not reliably informed by randomized trials (e.g., emergency surgery versus watchful waiting; spraying water versus spraying gasoline; etc.)- and thus, the conclusions of the world's best fire chiefs and trauma surgeons are “open to debate.” Does that imply that we should just let houses burn down, and watch people bleed?

The problem with this is the obvious one: ignoring the mass of observational information, predicated on actual outcomes in the real world. Were fixed criteria for evidence applied to all creatures, great and small, in the world's zoos, the conclusion would doubtless be reached that we have no basis to feed any of them anything-since all of the relevant insights are almost entirely observational; I have it on good authority that the koalas have ever been randomly assigned to wildebeest steaks, nor the lions to eucalyptus leaves. Since the evidence we have is debatable, I suppose we would thus be justified to starve them all, while waiting for better data.

Let us also recall it wasn't randomized trials that proved the harms of smoking. But it was arguments about the lack of randomized trials that aided and abetted the tobacco industry's efforts to stall actions against their poisonous product for years. The BMJ's strange saga, and disturbing if indirect ties to the beef industry, looks a lot like those calamitous follies of history, revisited.

Science for practical application, which is what the DGAC report is intended to be, cannot function independently of sense. We obviously know a lot about feeding captive animals, putting out fires, and treating gunshot wounds- the want of randomized trials notwithstanding.

The evidence base for diet is, in fact, much informed by RCTs and meta-analyses. But as the actual content experts in diet know, that's not remotely the whole story. There is no RCT or meta-analysis to tell us what the Blue Zones can tell us. There is no RCT to tell us what happens to an entire population's health over a span of decades when diet advice is well applied. The notion that such evidence is invalid for failing to meet some preconceived standard for evidence is every bit as sensible as tossing out everything we ever thought we knew about fire fighting for want of randomization.

Nutritional epidemiology is, ultimately, about the effects of dietary patterns on outcomes over lifetimes. Since little about that can be derived from RCTs, a robust blend of sense and science, intervention and observation, is necessary to reach even reasonable conclusions, let alone the right ones. The work of the DGAC explicitly embraced and represented just such principles.

My view accordingly, and in excellent company, is that not only the conclusions of the DGAC were right, but so were their methods in context. I would not expect experts in methods to know this; it requires expertise in both methods and content- namely, nutrition; the very expertise on abundant display among the members of the 2015 DGAC.

As for the reviews of the BMJ critique, they were in fact quite harsh, with one stating: ”The decision to publish the article as a BMJ Investigation is regrettable. The article is better described as an opinion piece, editorial, or even an example of lobbying literature than an independent investigation.”

The characterization of what the BMJ touted to be an “investigative article” as lobbying is truly brutal, with or without a retraction. The notion that the BMJ, or the author of the original critique, have cause to celebrate the lack of retraction in the context of scathing criticism like that is tantamount to celebrating your conviction for negligent homicide, since, after all, it's better than murder in the first degree.

Lack of clearly articulated dietary guidance based on the abundant and diverse evidence we have, including RCTs, would encourage the food industry to exploit us all even more appallingly than they already do. It would also suggest we really have absolutely no idea whether pinto beans or jelly beans, walnuts or doughnuts, cruciferous vegetables or Crisco were better for us. Because, let's face it- if you think you know which is better in any of these cases, I challenge you to cite the specific randomized trial on which that knowledge is based. As noted, science works best in the company of sense.

Apparently, the BMJ supported this statement: ”Given the ever increasing toll of obesity, diabetes, and heart disease, and the failure of existing strategies to make inroads in fighting these diseases, there is an urgent need to provide nutritional advice based on sound science.”

This assertion is misleading in every way imaginable. First, important health outcomes, such as rates of dementia and diabetes, actually are improving in the U.S., and in tandem with modest but real improvements in overall diet quality. For the most part, “existing strategies” failed to make inroads where they were never applied; where they were well applied, the inroads have been little less than stunning.

In the end, the BMJ's commissioned review of its commissioned critique appears to have been an exercise in face-saving. The reviewers focused solely on the methods of assimilating evidence, means not ends, and concluded that the best way to collate the world's evidence related to diet and health is debatable. Maybe, therefore, the DGAC methods were the best they could be, maybe not. Just about every colleague I have around the world would agree with that, as would every member of the DGAC itself.

How odd, though, that the review was silent on the topic dietary guidance is all about, namely: dietary guidance. This is especially bizarre since every parent of every child must use the “evidence” they have, and make decisions about food every day. Diet is not theoretical, and humans have been making decisions in this area based on observation and experience since long before the invention of science, let alone the launch of the BMJ.

One certainly understands, however, why the BMJ review avoided the big question: did the DGAC get it right by recommending wholesome foods, mostly plants, in sensible, heritage-based combinations? The committee's recommendations are informed by sense as well as science; line up well with the conclusions of other such groups commissioned by countries around the world; are massively informed by diverse evidence; and are supported by an overwhelming consensus of experts in disciplines from biochemistry to biodiversity, sustainability to agroecology, epidemiology to endocrinology, public health to clinical counseling, and vegan to Paleo. Arguments to eat more “meat, butter, and cheese,” well, not so much.

After all these months, it's tempting to look at the machinations of the BMJ as much ado about nothing. A biased opinion piece, badly marred by many errors and masquerading as investigation when it was, in fact, “lobbying,” was not retracted because the best ways to gather and interpret all that we know about diet and health are open to debate. Yes, that is true. But what it means is that, for all we know, the DGAC methods were as good or better than any others, to say nothing of the conclusions they reached.

However, there is reason for real consternation about this saga. In the age of the Paris Accord and water shortages, climate change and crop failures, The BMJ gets credit for helping the beef industry banish sustainability from nutrition policy in the United States.

Trained in methods of science or not, we all know the inevitable outcome were trauma surgeons, for want of systematic reviews of randomized trials, to do nothing while gunshot victims hemorrhaged: a tragic, awful, bloody mess. The summary contribution of the BMJ to dialogue about useful dietary guidance for human health, to say nothing of environmental impact, seemingly amounts to much the same.

So, the Center for Science in the Public Interest was quite correct to say that the BMJ has made a bloody mess of dietary guidance, and has a stain on its reputation. Now, we even know the color.

David L. Katz, MD, FACP, MPH, FACPM, is an internationally renowned authority on nutrition, weight management, and the prevention of chronic disease, and an internationally recognized leader in integrative medicine and patient-centered care. He is a board certified specialist in both Internal Medicine, and Preventive Medicine/Public Health, and Associate Professor (adjunct) in Public Health Practice at the Yale University School of Medicine. He is the Director and founder (1998) of Yale University's Prevention Research Center; Director and founder of the Integrative Medicine Center at Griffin Hospital (2000) in Derby, Conn.; founder and president of the non-profit Turn the Tide Foundation; and formerly the Director of Medical Studies in Public Health at the Yale School of Medicine for eight years. This post originally appeared on his blog at The Huffington Post.