American College of Physicians: Internal Medicine — Doctors for Adults ®

Monday, November 19, 2012

Multivitamins and multiplication

As has likely come to your attention by now, a new study shows that daily multivitamin use is associated with a significant reduction in the overall rate of cancer. This is clearly important, and warrants careful consideration in the context of what we already knew, or thought we knew, about multi-nutrient supplementation.

For a long time, the prevailing view of multis, which as a rule contain a mix of vitamins and minerals, most at or above the level of recommended daily intake, was that they could and probably should help, and couldn't hurt. Nutrient levels were based on the Dietary Reference Intakes of the Institute of Medicine, and in general all or nearly all of the micronutrients known to be essential were in the mix.

There was always a sound rationale for such supplementation. Average intake in the U.S. of quite a few nutrients is lower than recommended, and intake of quite a few more is lower than optimal. In particular, as people get older, there is a tendency for both calories and dietary variety to fall, resulting in a rising risk for nutrient deficiencies. Few of these are bad enough to present as overt deficiency syndromes, but even nominal deficits of key nutrients may compromise health. And some cases of overt deficiency, notably of vitamins B12, folate, iron, and calcium, are seen.

This all seemed to make a robust argument for routine supplementation, in particular by those over age 50. Most doctors recommended the practice routinely, as did I. And, of course, the supplement industry made hay predictably, providing a wide array of products that competed for attention with claims about nutrient quality, quantity, variety, and customization.

But then the notion that multis could help but "couldn't hurt" started to take a beating. First came a long line of clinical trials suggesting lack of benefit and potential harm from high doses of select nutrients. Then came studies showing associations between multivitamin use and adverse outcomes, in particular, a higher rate of breast cancer among women.

Since we never had clear evidence of a benefit, even a hint of potential harm from multis was enough to argue pretty powerfully against their routine use. I stopped taking one, and stopped recommending them to my patients in the absence of a clear reason.

I never abandoned supplementation entirely, of course. In general, my clinic recommends supplements to do a particular job. So, for instance, we use omega-3s routinely to reduce inflammation, probiotics to improve gastrointestinal health and immune function, and vitamin D whenever levels are low. We use a wide range of other supplements when there is a specific case for doing so.

As for multis, I switched over to recommending them only when there was a meaningful likelihood of dietary deficits and, for whatever reason, an inability to fix them with food. I also switched from conventional multis to "whole-food-based supplements." I still think those are a good idea, and here's why:

If multis do harm, there must be a reason, and the most plausible one is a problem of "nutritional noise." Imagine, for instance, that a great electric guitar player from a rock band, a great sax player from a jazz ensemble, and a virtuoso cellist from a symphony orchestra play their own brand of music all at once. No matter how good each is when in the his/her native context, the result of this mishmash would be unpleasant noise.

In putting together multis, we, not nature, have chosen the dose, preparation, and variety of nutrients, and taken them all out of their native context in food. We know that nutrients, like musicians, work best in concert with one another. If we have assembled them wrong, they might clash. Nutritional noise could be harmful.

Whole-food-based supplements avoid this potential danger because they preserve the native context of nutrients in foods. This may facilitate the work of nutrients in concert with one another, and make far more beautiful music in our metabolism. It's theoretical, but makes good sense.

But now we have the new study, and it does invite some reconsideration of the traditional multi. The findings, reported in JAMA, are based on a randomized, blinded, placebo-controlled intervention among nearly 15,000 U.S. male physicians followed for more than 10 years. There were 8% fewer cancers overall in those who took the multivitamin, and this was statistically significant, although barely so. There were no significant effects on any particular cancer, none on cancer mortality, and none on all-cause mortality.

So the findings are intriguing and promising, but far from the proverbial slam-dunk. And they are limited to a population of male doctors age 50 and older. How they pertain to women, younger people, or populations who behave differently on average than doctors, is unknown.

So where does it leave us?

We had seen the gradual accumulation of evidence for potential harm from multivitamins. This study does not eradicate that, but it does suggest that in some populations at least, there is potential for net benefit. Judicious use of multivitamins by men age 50 and older is, if not obviously advisable, perfectly reasonable given what we do and don't know at present.

The theoretical case for whole-food-based supplements remains valid, and absence of evidence is not evidence of absence. We don't have a trial like this using supplements like that, so we are left to speculate about the potential for greater benefits.

We once thought multis could do good and couldn't do harm. We then learned they could do harm, and developed doubts about them doing any good. Our current understanding is far from perfect, but it seems to suggest some potential for both. This invites discussion between patients and doctors, and customized decisions based on personal circumstance. That may not be an entirely satisfying resolution, but anything else would run ahead of the evidence we've got. This study revises our risk/benefit assessment, it is not a basis to renounce it.

But the most important take away here has to do with the size of effects, rather than their direction. A relative reduction of 8% in the overall rate of cancer is better than nothing, but it is a small effect. In contrast, studies from 1993, 2004, 2009, 2010, and 2011, just to name a few, show that the combination of not smoking, eating well, and being active can reduce the risk of all chronic disease, cancer included, and premature death from any cause by as much as 80%. That is a tenfold multiplication of the best effect of multivitamins yet shown. You certainly want that math on your side!

So whether you choose to take a multi or not, remember it's a supplement, not a substitute. There is no substitute for the profound health benefits of a daily dose of well-chosen lifestyle as medicine.

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.

Labels: , , , , ,


Post a Comment

Subscribe to Post Comments [Atom]

<< Home

This is a printer-friendly version of this page

Print this page  |  Close the preview




Contact ACP Internist

Send comments to ACP Internist staff at

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.

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.

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.

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.

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).

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.

Powered by Blogger

RSS feed