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

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Friday, April 19, 2013

Is a high calcium diet and calcium supplementation bad for you?

An article from Sweden was recently published showing that in a very large group of women, over 60,000 of them, followed for 19 years as part of an also very interesting study of the effectiveness of mammograms, women who get more calcium, in their diet or as supplements, had a higher risk of dying of anything, but especially of heart attacks. It is unclear why this would be true, but there are various theories.

Further, the study showed that this risk was more pronounced if the calcium was taken as supplements, but still present in women who got their calcium from the food they ate. The highest level of risk was in women who got more than 1,400 mg of calcium a day, and an intake of 700-1,000 mg a day did not particularly increase risk. The women with the lowest average calcium intake were not at any increased risk of death, which was a surprise to the researchers. Information about calcium intake was taken from the subjects' reports of diet and supplement use, which was further validated by phone interviews of recent food intake. Since most women think that consuming calcium is healthy, I would guess that there was a tendency to overestimate calcium intake, suggesting that real risk may be present with lower calcium intakes than the study states.

This is big news. Or is it? No, it actually isn't. In 2010 the British Medical Journal published a meta-analysis of studies of calcium supplementation in healthy people and concluded that there was increased cardiovascular death in those given supplements. There had previously been studies showing that calcium supplements in dialysis patients accelerated calcium deposition in blood vessels and increased cardiovascular death.

It has been part of our general medical wisdom for my many years of practice to recommend calcium, as food or pills, to our women patients. I remember several years ago when we began to be aware of the real impact of osteoporotic hip and spinal fractures in our aging population that physicians were encouraged to recommend to our post-menopausal patients that they take 1,200-1,600 mg a day of calcium. That was very hard to do. A cup of milk contains about 300 mg of elemental calcium, yogurt slightly more, cheese not much at all. Calcium fortified orange juice was about as much as milk. Dark green leafy vegetables contain calcium, but not a whole lot. A cup of collard greens, cooked, contains about 350 mg, but people rarely eat that much cooked greens. I would work through how to get all that calcium in the diet and usually suggest my patient take a chewable calcium pill for every meal they didn't eat something that was high in calcium. Luckily for my patients, I doubt many of them really did this.

Calcium supplementation seemed the right thing to recommend after estrogen, which is well known to reduce fracture risk, was discredited by the Women's Health Initiative due to what appeared to be an excess of heart attacks and strokes in treated patients. There were other medications for osteoporosis, but they had side effects and were really only approved for established osteoporosis, which most patients don't want to wait to get.

But why did we ever recommend calcium supplements at all? Did we have any good evidence that they worked? Sort of, but in retrospect, not really.

It does make sense, when you think about it, that calcium would strengthen bones. Bones are, after all, made mostly of calcium. Over the last three decades at least we have studied the effects of calcium supplementation on both bone density and on risk of fracture. We care most about risk of fracture, because bone density is just a test, and is not necessarily indicative of whether a person will break a bone. The most important kinds of fractures as we age are those of the hips and vertebrae. These are the ones that cause disability and death and are associated with the thinning of bones that comes to many of us with age, that is to say osteoporosis. Although some studies early on appeared to show that taking calcium, with or without vitamin D, reduced these important fractures, later analysis of all of the well done studies showed no benefit. There was even a suggestion that higher calcium intake might have been associated with more hip fractures. Many of these studies were done in the most scrupulous way possible, using double blind prospective methodology or correcting for factors that might make patients with higher calcium intake be those who were at higher risk of fracture in the first place.

What about vitamin D? Does this make a difference? In the Swedish mammography cohort, vitamin D supplementation did not reduce the risk of heart attack or death that was associated with increased calcium intake. In a recent large study out of Finland from 2010, combining calcium and vitamin D had a slight but not statistically significant effect on fracture risk in a group of 65-71 year old women living in northern Finland. Vitamin D itself is the subject of lots of research and although it may be good to supplement it, especially in people with risks for low levels, it is not clear that it reduces the risk of fracture in the majority of post-menopausal women.

So what is the bottom line here? It does appear that taking calcium supplements and deliberately pushing high calcium foods increases risk for death and doesn't save a person from disabling fractures. Doctors have so many things that they need to advise people about in a preventive office visit, getting exercise, quitting smoking, controlling their blood pressure, getting vaccinated against dread diseases. Now we just don't have to also tell our patients to drink milk and take large and unpalatable calcium pills. We should probably tell them if they are already doing that, to stop the pills and concentrate more on a healthy balanced diet, with plenty of fruit and vegetables and fish and olive oil. We can rejoice in having one less thing to fuss about!

Janice Boughton, MD, ACP Member, practiced in the Seattle area for four years and in rural Idaho for 17 years before deciding to take a few years off to see more places, learn more about medicine and increase her knowledge base and perspective by practicing hospital and primary care medicine as a locum tenens physician. She lives in Idaho when not traveling. Disturbed by various aspects of the practice of medicine that make no sense and concerned about the cost of providing health care to every American, she blogs at Why is American Health care so expensive?, where this post originally appeared.

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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 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.

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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