Calcium and Vitamin D Supplements for Orthopedic Patients?

Laird Harrison

Disclosures

October 12, 2016

Confusion About Vitamin D and Calcium

Every year, Susan Bukata, MD, goes to the annual meeting of the American Society of Bone and Mineral Research. She gives presentations and attends them, scooping up the latest data and hobnobbing with some of the world's foremost authorities on calcium and vitamin D. But somehow, all the new information makes these nutrients more mysterious.

"Every year, I leave more confused than when I got there," says Dr Bukata, who is vice chair of orthopedics at the University of California, Los Angeles Medical Center, Santa Monica, and a board member of the National Osteoporosis Foundation.

So it's no surprise that orthopedic surgeons in the trenches often wonder whether to recommend supplements to their patients.

The matter is not just academic. Patients who get too little calcium and vitamin D, can break bones and not heal well from surgery. And those who get too much can suffer a range of effects, from constipation to heart disease. But what is the right amount?

For the time being, Dr Bukata and most other leading authorities in the United States recommend that doctors stick, more or less, to the 2010 Institute of Medicine (IOM) recommendations.[1] Although amounts vary by sex and age, the recommended dietary intake for most people is about 1000 mg/day of calcium and 600 IU/day of vitamin D.

Dissent Among Experts

In the 6 years since those recommendations were issued, researcher groups have challenged the foundation of this advice, including the US Preventive Services Task Force (USPSTF), which concluded in 2013 that there was insufficient evidence for it.[2] The USPSTF is currently reviewing the data and plans to release an update in 2018.

There is plenty to review. In the 1970s, researchers began to measure how much calcium people were excreting and how much they were taking in. If excretion was greater than intake, they theorized, bones would get weaker and become more susceptible to fracture.

That theory gained traction in 1992, when a large randomized trial showed that elderly women taking calcium and vitamin D supplements were 43% less likely to break their hips than those in a matched control group taking a placebo.[3] But the women in the study cohort lived in institutions and had low serum vitamin D at baseline.

Since then, numerous randomized controlled trials have revealed ambiguous results. "Most people don't need to worry about their calcium at all," Mark Bolland, MBChB, PhD, associate professor of medicine at the University of Auckland in New Zealand, told Medscape Medical News last year after he and his colleagues published two meta-analyses on the mineral.[4]

Dr Bolland's team combined data from 26 studies, and calculated that calcium supplements reduced total fractures by 11% and vertebral fractures by 14%, but did not reduce hip or forearm fractures. These researchers concluded that, for most people, the risks related to calcium supplementation could outweigh the benefits.

These risks include cardiovascular events, kidney stones, and hospital admission for acute gastrointestinal symptoms.[4]

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