Monday, October 14, 2013
Genes, germs and girth
We have, it seems, moved on from acknowledging it takes a village to raise a human being. We are well into the realm of realization that it takes a village just to be one. More and more studies are demonstrating the importance of the germs that outnumber our cells by an order of magnitude at least, to virtually every aspect of physiology. But while epiphanies of this sort are redolent with promise, they can be dizzying as well, and pose a threat of disequilibrium and distraction. If we can miss the forest for the trees, there is, I think, a comparable risk of missing the importance of lifestyle for the Lactobacilli. My motivation here is the hope that we will not.
While I can no longer readily recall what life was like before e-mail, I certainly do recall medical practice before the widespread popularity of probiotics. Only very recently did the use of ingestible bacteria transition from the realm of far-fetched to all-but-standard, and from “you must be kidding!” to “where to do I get mine?” Not all that long ago, the only good germ was a dead germ.
Progress since the initial uptake of the probiotic concept has been astounding. The now well-established potential to prevent and treat Clostridium difficile colitis, a dire complication of antibiotic therapy, with probiotics is a considerable advance all by itself.
The more we’ve learned about the importance of our resident microbes, the more we’ve learned about the need and opportunity to learn more. The process may be likened to climbing a hill, and then gaining a view of the higher hills and mountains beyond. There is a lot of climbing left to do.
One peak now within view involves the important relationships among our immune system, cohabiting bacteria, and other organisms. In An Epidemic of Absence, Moises Velaszquez-Manoff makes a thorough and compelling case for the unintended consequences of sanitizing our environments and the eradication of parasites. How best to apply such lessons to the management of allergy and autoimmune disease is a work in progress, but that it’s vitally important work now seems abundantly clear.
The other peak before us is the one that worries me a bit. It beckons with tantalizing new findings related to weight control.
We have known for quite some time that commensal microbes play a vital role in digestion. In fact, we surmised this about bacteria living in our guts before we knew much else about them; after all, what else would they be doing there? More recently, we have come to learn that bacterial colony counts influence our energy efficiency and the number of calories we can extract from food. Differences in the microbiome can make it harder or easier to lose weight, and may account for more flagrant cases of weight loss resistance. In some instances, when all else fails, the wholesale transplantation of gut microbes may allow for weight control.
This provocative tale is further embellished by a cluster of recent papers in preeminent scientific journals. An article published in Nature Reviews in early August explores the causal pathway from intestinal microbes to obesity risk. A study published in late August in Nature compared the microbiota in 123 lean and 169 obese Danish adults. The authors report greater genetic variety among gut microbes in lean individuals than obese. A brief report of an intervention in the same issue of the journal reported an increase in the genetic richness of gut microbes when obese and overweight individuals were put on a weight-reducing diet. And even more of Nature’s rarefied real estate has been allocated to this topic to accommodate commentaries and editorials.
And hot off the presses is a report in Science, indicating that the gut microbes from obese adult twins could make germ-free mice get fat, while the gut microbes from their lean siblings had the opposite effect.
Why does this all worry me?
I fully acknowledge the almost certain importance of our microbial diversity to energy balance and weight regulation. I accept that indelible links are being forged among genes, germs, and resultant girth.
But we are all too easily distracted from the accessible means of both losing weight and finding health, by new and exotic theories. Excessive preoccupation with the microbiome could lead us into our next great boondoggle.
Consider that behaviors we control directly, as opposed to microbial colonies we may not, explain 80 percent of the variation in the risk for all major chronic diseases. Consider that overwhelmingly, when people eat well and exercise, they lose weight, and if the behaviors persist, so does the weight loss. Consider that obesity was rather uncommon a half century ago in the days before drive-through fast-food restaurants, a vast proliferation of junk foods, and a comparable proliferation of labor-saving technologies.
In other words, while scrutiny of our microbes may help account for enigmatic cases of weight gain, they are, for most of us, the trees that may cause us to overlook the forest. The fixable causes of obesity and chronic disease are on prominent display, all around us. Most of us will gain weight when we take in too many calories, even if from wholesome sources. Most of us will lose weight if we restrict calories enough, even if those calories come from Twinkies. Energy balance does not seem to require a bacterial referendum.
For the most part, people who exercise diligently and eat very well are both leaner and healthier than others who don’t. What a remarkable coincidence it would be if those who best attended to calories in and calories out just happened to be those with the genes and germs conducive to trim guts.
This does not mean the germs and genes in our guts are not germane to weight and health; they clearly are. But the available evidence suggests they are at least as much effects as causes.
In other words, the same adverse exposures that tend to make us sick and fat appear to do much the same to our resident bugs. It doesn’t much change the relevance of junky diets and physical inactivity to poor health and weight gain to note that along with all of the other adverse effects of such behaviors, they disrupt and distort the microbiome. All this really means as that we, and our germs, are in this together. We flourish, or founder, together.
For a quick analogy, imagine if we had just discovered atherosclerosis and reached the conclusion that it is the “real” cause of heart disease. That would be true, but it would be a serious mistake to toss out what we knew about tobacco, physical activity, and diet as a result. Those factors influence atherosclerosis, which in turn influences the likelihood of heart attack. Similarly, shifts in our bacterial colonies may be part of the pathway by which behaviors translate into changes in both weight, and health. This is in no way an invitation to jettison anything we already knew about the importance of those behaviors.
There may well be some opportunities to address the microbiome directly, from probiotics to fecal transplant. There are, analogously, ways to address atherosclerotic plaque directly with angioplasty and coronary bypass surgery. But just as lifestyle can keep arteries healthy in the first place, or even restore them to health, so too, it seems, can the very same lifestyle practices that protect our health do the same for our inner menagerie.
Over the years, we have heard about many “obesity genes.” But these genes were around long before obesity was a salient public health concern. Genes that haven’t changed recently can’t really account for recent changes in epidemiology. Similarly, while our understanding of our intimate codependence on gut microbes is fairly recent, the codependence is not. The bugs were there all along. If they have suddenly become complicit in epidemic obesity, it might be tempting to pass the buck to the bugs, but it begs the question: What changed them?
This, in turn, offers the silver lining of insight within the dark clouds of potential diversion. One of the prevailing mistakes about obesity is to pin it all on personal responsibility. There is, clearly, a case for personal responsibility; but the choices we make are in turn governed by the choices we have. It never made sense to presume that the current generation of 7-year-olds was less endowed with personal responsibility than every prior generation of 7-year-olds; but they sure are fatter! It makes even less sense to ascribe less personal responsibility to the current generation of Saccharomyces.
Of course, the “fault” lies not in our Saccharomyces! The explanations for what is awry within us are all around us; the very factors of lifestyle, environment and culture that have changed us have changed our resident flora as well. The behaviors that lead to better health and healthier weight may do so in part by moderating the expression of genes, and favorably shifting the populations of gut microbes.
It takes a healthy village within, it seems, to be a healthy human being. It still takes healthy choices by that human being to tend the village.
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.
Contact ACP Internist
Send comments to ACP Internist staff at firstname.lastname@example.org.
- Naturopathic medicine and the answer to the challe...
- QD: News Every Day--For low back pain, no MRIs in ...
- The movement to improve patient notes
- QD: News Every Day--NSAIDs, antibiotics make littl...
- MRSA rates continue to decline, but not in the com...
- QD: News Every Day--'Soft' pneumonia diagnosis on ...
- Force-feeding Guantanamo prisoners tortures medica...
- Water, hand sanitization and other technologies to...
- QD: News Every Day--Overdoses on prescription drug...
- Senate declares Naturopathic Medicine Week, Wizard...
Members of the American College of Physicians contribute posts from their own sites to ACP Internistand ACP Hospitalist. Contributors include:
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.
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, 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
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 Richmond, Va., 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.
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.
Toni Brayer, MD, FACP, blogs about the rapid changes in science, medicine, health and healing in the 21st century.
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.
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.
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.
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.
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.
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.
Kevin Pho, MD, ACP Member, offers one of the Web's definitive sites for influential health commentary.
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.
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.
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).
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
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)
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,
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
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.
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.
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.
The Public Library of Science's open access materials include a blog.
One of the most popular anonymous blogs written by an emergency room physician.