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Wednesday, August 26, 2015

Zeal, veal and veganism

When my vegan friends and colleagues say that a vegan diet is categorically the best for human health, it is an excess of zeal. We simply do not have evidence to substantiate the claim. I know; I've looked, hard.

If you are inclined to doubt my assertion, just consider what such evidence would look like. I don't think, when we say “best for human health,” that any of us really means: produces the lowest LDL over a 6-month period. I don't think we mean produces the highest antioxidant levels in the blood, or the lowest blood pressure over a span of months either. I think what we really mean is: leads, on average, to the most years in life, and the most life in years over an entire lifetime. The “best health” is enjoyed by people who live long, and prosper from their enduring vitality.

Given that, the trial to show that any given diet is truly “the best” has not been done, and is unlikely ever to be done. First, the outcome measure would need to be a composite of years in life and life in years over a lifetime, meaning something like quality-adjusted life years measured over many decades. The trial would need to run for 100 years.

Second, if we are to measure the effects of diet on health, we have to consider that those effects may be exerted early, late, or in between. For instance, we have some reason to believe that it is the diet and health of young girls that most influences the likelihood of breast cancer in the women they will become. With such considerations in mind, our intervention would need to cover all phases of the life cycle to be robust.

I could keep going, but the conclusion is already clear, so let's just stipulate it. To show, decisively, that any given diet is “best” for human health would require randomly assigning a large number of women soon to become pregnant to each of the competing dietary assignments, since we know that dietary effects begin in utero. Then, each of the neonates would need to be breast fed by a mother adhering to their dietary assignment, and then after all being weaned at the same time, the babies would need to adopt their diet: vegan; Mediterranean; Paleo; etc. They would then need to be followed for the rest of their lives to determine which group “wins.” The investigators planning and running the trial would not live to see it concluded, and the cost would be stupefying.

So, no, it has not been done, and won't be. The result is we have a vast amount of evidence about the fundamentals of healthy eating, and no definitive evidence to say which variant on the well-established theme is truly the best. Claims to the contrary are, as noted, born of zeal.

I note in passing that the direct comparisons of “this” dietary pattern to “that” suffer a variety of important limitations. Generally, they are of rather short duration, and none has ever run for the decades required to give us meaningful data about lifelong effects. Generally, they are directed at a primary outcome of only secondary significance, such as weight, or blood pressure. Most importantly, all such comparisons tend to be conducted by investigators with a particular interest in a particular diet, and that diet inevitably gets favorable treatment. Those, for instance, seeking to show the benefits of a low-carb diet will tend to compare it to a straw man version of a low-fat diet; and vice versa, just as surely. What we really need, and never get, if we are to say what specific diet is truly “best” for health, is a comparison of the optimal version of each contestant to its comparably optimized counterparts. Good luck finding that.

Because of this, claims that any given diet is the one best choice for human health represent the triumph of rhetoric over research. The evidence is not there; not for those in the vegan vanguard, not for the adamant Paleo proponents. Just as surely, the evidence is there- abundantly, consistently, and transculturally -- for the fundamentals of healthy eating that transcend the claims for any specific variant on the theme.

I am not a vegan myself. I eat a mostly, but not exclusively, plant-based diet. But my sympathies angle toward the vegans, for various reasons. Consequently, I generally regret the excessive zeal and unverifiable claims about health made to advance the vegetarian cause; they are unnecessary. There are important considerations in the mix other than human health.

Human beings are, irrefutably, omnivorous. There are specific aspects of our physiology particular to meat consumption, and perhaps even the consumption of cooked meat per se. There are adaptations even since the advent of civilization that are particular to dairy consumption. Valid arguments over the place of dietary meat and dairy in human health are far more challenging and nuanced than the opposing clamors would suggest, and might well come down to: what meat, and which kind of dairy?

But there are considerations other than human health we simply cannot ignore. I cannot improve on a recent headline in IFLScience: “meat is a complex health issue but a simple climate one.” Amen. Whatever the arguments for the merits of game in the diet, they just don't pertain to a population of 7 billion Homo sapiens busily cooking their planet.

I'm mostly with the vegans as well on the issue of ethics. I don't, by any means, think it is intrinsically unethical to eat meat; many of our fellow species do so, and some have no choice. But we humans, obviously, don't just hunt, kill, and eat animals anymore. We at times torture and abuse them. We force feed and fatten them.

Our capacity for double-bookkeeping on the subject is impressive. I imagine, for instance, that some who enjoy a visit to their neighborhood zoo in the spring to see the delightful antics of newly born animals might also enjoy veal parmigiana. Veal, as you no doubt know, is the flesh of calves; animals raised to be slaughtered, and eaten, while in that very phase of exuberant youth that makes closely related animals at the zoo so captivating. While standards of treatment have improved, veal historically comes from calves that are fattened and tenderized by strict confinement all the days of their short lives. There is the comparably incongruous tendency to adopt into our very families some beloved, four-legged mammals; while putting others of equal or greater intelligence and sensitivity on our dinner plates. That's not cannibalism exactly, but it's not entirely rational, either.

Among my many detractors out here in cyberspace are some inclined to beat me over the head with a figurative leg of lamb as a matter of routine. They seem to imply they have personally discovered the tonifying wonders of meat, to which I am oblivious. They state explicitly that my arguments for mostly plant-based eating by the human population at large make me benighted, unenlightened, ignorant, and/or conflicted. But they are wrong.

I am a public health pragmatist, not an ideologue. I know that debate over the health benefits of grass-fed beef will be moot when we've run out of water to grow grass. I know that the relative contributions of salmon to our health will be impertinent after we've eaten the last one.

The vast preponderance of real-world evidence of health outcomes in actual populations argues for diets of food, not too much, mostly plants. That could be enough. If it's not, we might constructively consider the plight of the planet, or the sorry fate of those veal calves.

There simply is no need for overzealous argument to make the case that we are in serious trouble if we keep eating as if the future does not depend on our choices. It does.

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.

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1 Comments:

Anonymous Anonymous said...

Amen, brother! We're NOT all the same, and weren't produced in a factory, so why should we all be told to eat one government-backed eating formula? Ancel Keys and an army of lobbyists is why--forceful personalities and flowing money is how we got here, and too many of us are too lazy to climb out of the box to find out what works for them.

August 30, 2015 at 4:39 AM  

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Blog log

Members of the American College of Physicians contribute posts from their own sites to ACP Internistand ACP Hospitalist. Contributors include:

Albert Fuchs, MD
Albert Fuchs, MD, FACP, graduated from the University of California, Los Angeles School of Medicine, where he also did his internal medicine training. Certified by the American Board of Internal Medicine, Dr. Fuchs spent three years as a full-time faculty member at UCLA School of Medicine before opening his private practice in Beverly Hills in 2000.

And Thus, It Begins
Amanda Xi, ACP Medical Student Member, is a first-year medical student at the OUWB School of Medicine, charter class of 2015, in Rochester, Mich., from which she which chronicles her journey through medical training from day 1 of medical school.

Auscultation
Ira S. Nash, MD, FACP, is the senior vice president and executive director of the North Shore-LIJ Medical Group, and a professor of Cardiology and Population Health at Hofstra North Shore-LIJ School of Medicine. He is Board Certified in Internal Medicine and Cardiovascular Diseases and was in the private practice of cardiology before joining the full-time faculty of Massachusetts General Hospital.

Zackary Berger
Zackary Berger, MD, ACP Member, is a primary care doctor and general internist in the Division of General Internal Medicine at Johns Hopkins. His research interests include doctor-patient communication, bioethics, and systematic reviews.

Controversies in Hospital Infection Prevention
Run by three ACP Fellows, this blog ponders vexing issues in infection prevention and control, inside and outside the hospital. Daniel J Diekema, MD, FACP, practices infectious diseases, clinical microbiology, and hospital epidemiology in Iowa City, Iowa, splitting time between seeing patients with infectious diseases, diagnosing infections in the microbiology laboratory, and trying to prevent infections in the hospital. Michael B. Edmond, MD, FACP, is a hospital epidemiologist in Iowa City, IA, with a focus on understanding why infections occur in the hospital and ways to prevent these infections, and sees patients in the inpatient and outpatient settings. Eli N. Perencevich, MD, ACP Member, is an infectious disease physician and epidemiologist in Iowa City, Iowa, who studies methods to halt the spread of resistant bacteria in our hospitals (including novel ways to get everyone to wash their hands).

db's Medical Rants
Robert M. Centor, MD, FACP, contributes short essays contemplating medicine and the health care system.

Suneel Dhand, MD, ACP Member
Suneel Dhand, MD, ACP Member, is a practicing physician in Massachusetts. He has published numerous articles in clinical medicine, covering a wide range of specialty areas including; pulmonology, cardiology, endocrinology, hematology, and infectious disease. He has also authored chapters in the prestigious "5-Minute Clinical Consult" medical textbook. His other clinical interests include quality improvement, hospital safety, hospital utilization, and the use of technology in health care.

DrDialogue
Juliet K. Mavromatis, MD, FACP, provides a conversation about health topics for patients and health professionals.

Dr. Mintz' Blog
Matthew Mintz, MD, FACP, has practiced internal medicine for more than a decade and is an Associate Professor of Medicine at an academic medical center on the East Coast. His time is split between teaching medical students and residents, and caring for patients.

Everything Health
Toni Brayer, MD, FACP, blogs about the rapid changes in science, medicine, health and healing in the 21st century.

FutureDocs
Vineet Arora, MD, FACP, is Associate Program Director for the Internal Medicine Residency and Assistant Dean of Scholarship & Discovery at the Pritzker School of Medicine for the University of Chicago. Her education and research focus is on resident duty hours, patient handoffs, medical professionalism, and quality of hospital care. She is also an academic hospitalist.

Glass Hospital
John H. Schumann, MD, FACP, provides transparency on the workings of medical practice and the complexities of hospital care, illuminates the emotional and cognitive aspects of caregiving and decision-making from the perspective of an active primary care physician, and offers behind-the-scenes portraits of hospital sanctums and the people who inhabit them.

Gut Check
Ryan Madanick, MD, ACP Member, is a gastroenterologist at the University of North Carolina School of Medicine, and the Program Director for the GI & Hepatology Fellowship Program. He specializes in diseases of the esophagus, with a strong interest in the diagnosis and treatment of patients who have difficult-to-manage esophageal problems such as refractory GERD, heartburn, and chest pain.

I'm dok
Mike Aref, MD, PhD, FACP, is an academic hospitalist with an interest in basic and clinical science and education, with interests in noninvasive monitoring and diagnostic testing using novel bedside imaging modalities, diagnostic reasoning, medical informatics, new medical education modalities, pre-code/code management, palliative care, patient-physician communication, quality improvement, and quantitative biomedical imaging.

Informatics Professor
William Hersh, MD, FACP, Professor and Chair, Department of Medical Informatics & Clinical Epidemiology, Oregon Health & Science University, posts his thoughts on various topics related to biomedical and health informatics.

David Katz, MD
David L. Katz, MD, MPH, FACP, 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.

Just Oncology
Richard Just, MD, ACP Member, has 36 years in clinical practice of hematology and medical oncology. His blog is a joint publication with Gregg Masters, MPH.

KevinMD
Kevin Pho, MD, ACP Member, offers one of the Web's definitive sites for influential health commentary.

MD Whistleblower
Michael Kirsch, MD, FACP, addresses the joys and challenges of medical practice, including controversies in the doctor-patient relationship, medical ethics and measuring medical quality. When he's not writing, he's performing colonoscopies.

Medical Lessons
Elaine Schattner, MD, FACP, shares her ideas on education, ethics in medicine, health care news and culture. Her views on medicine are informed by her past experiences in caring for patients, as a researcher in cancer immunology, and as a patient who's had breast cancer.

Mired in MedEd
Alexander M. Djuricich, MD, FACP, is the Associate Dean for Continuing Medical Education (CME), and a Program Director in Medicine-Pediatrics at the Indiana University School of Medicine in Indianapolis, where he blogs about medical education.

More Musings
Rob Lamberts, MD, ACP Member, a med-peds and general practice internist, returns with "volume 2" of his personal musings about medicine, life, armadillos and Sasquatch at More Musings (of a Distractible Kind).

Prescriptions
David M. Sack, MD, FACP, practices general gastroenterology at a small community hospital in Connecticut. His blog is a series of musings on medicine, medical care, the health care system and medical ethics, in no particular order.

Reflections of a Grady Doctor
Kimberly Manning, MD, FACP, reflects on the personal side of being a doctor in a community hospital in Atlanta.

The Blog of Paul Sufka
Paul Sufka, MD, ACP Member, is a board certified rheumatologist in St. Paul, Minn. He was a chief resident in internal medicine with the University of Minnesota and then completed his fellowship training in rheumatology in June 2011 at the University of Minnesota Department of Rheumatology. His interests include the use of technology in medicine.

Technology in (Medical) Education
Neil Mehta, MBBS, MS, FACP, is interested in use of technology in education, social media and networking, practice management and evidence-based medicine tools, personal information and knowledge management.

Peter A. Lipson, MD
Peter A. Lipson, MD, ACP Member, is a practicing internist and teaching physician in Southeast Michigan. The blog, which has been around in various forms since 2007, offers musings on the intersection of science, medicine, and culture.

Why is American Health Care So Expensive?
Janice Boughton, MD, FACP, practiced internal medicine for 20 years before adopting a career in hospital and primary care medicine as a locum tenens physician. She lives in Idaho when not traveling.

World's Best Site
Daniel Ginsberg, MD, FACP, is an internal medicine physician who has avidly applied computers to medicine since 1986, when he first wrote medically oriented computer programs. He is in practice in Tacoma, Washington.

Other blogs of note:

American Journal of Medicine
Also known as the Green Journal, the American Journal of Medicine publishes original clinical articles of interest to physicians in internal medicine and its subspecialities, both in academia and community-based practice.

Clinical Correlations
A collaborative medical blog started by Neil Shapiro, MD, ACP Member, associate program director at New York University Medical Center's internal medicine residency program. Faculty, residents and students contribute case studies, mystery quizzes, news, commentary and more.

Interact MD
Michael Benjamin, MD, ACP member, doesn't accept industry money so he can create an independent, clinician-reviewed space on the Internet for physicians to report and comment on the medical news of the day.

PLoS Blog
The Public Library of Science's open access materials include a blog.

White Coat Rants
One of the most popular anonymous blogs written by an emergency room physician.

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