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Calcium and vitamin D supplements do not protect against fractures, meta-analysis finds

Vitamin D
CC/Flickr/Laura B. Dahl
People taking vitamin D supplements were no less likely to experience a hip or other fracture than those who didn’t take them.

The use of calcium and vitamin D supplements does not appear to protect older adults from breaking their hips or other bones, according to a major new study published last week in the Journal of the American Medical Association (JAMA).

The study, a meta-analysis, examined data from 33 randomized clinical trials (considered the gold standard in research) published within the past decade. Each trial compared the use of supplements (calcium, vitamin D or a combination of the two) with a placebo or no treatment to determine if the supplements had any effect on preventing new fractures.

A total of 51,145 adults over age 50 took part in the 33 trials. The participants lived on their own in their communities and not in institutions, such as nursing homes or other residential-care facilities.  

After diving deeply into all that data, the authors of the meta-analysis concluded that people taking calcium and/or vitamin D supplements were no less likely to experience a hip or other fracture than those who didn’t take them.

That finding held even when the researchers adjusted for the participants’ gender, past history of bone fractures, the amount of calcium in their diet, and the amount of vitamin D in their blood when they enrolled in the clinical trial. Nor did the amount of calcium or vitamin D in the supplements (if they were taking them) make a difference.

The meta-analysis also found that people with at least 20 nanograms per milliliter of vitamin D in their blood — an amount considered healthy — were at an increased risk of hip fracture if they subsequently started taking vitamin D supplements. The reason for this association was unclear, the study’s authors write.

Need for a change

“It is time to stop taking calcium and vitamin D supplements for the community-dwelling older adults,” Dr. Jia-Guo Zhao, the study’s lead author and a researcher in the department of orthopedic surgery at Tianjin Hospital in China, told Reuters News.

“The guidelines should be changed,” he added. “We think that improving the lifestyle, getting enough exercise and enough sunshine, and adjusting the diet may be more important than taking these supplements.” 

The exception is older people living in nursing homes or other residential facilities. As Zhao and his co-authors explain in their paper, people living in such institutions are more likely to have a vitamin-deficient diet and poor mobility. They are also less likely to be exposed to the sun. (Sunlight helps the skin produce usable vitamin D.)

Current U.S. recommended guidelines for calcium are 1,000 to 1,200 milligrams of calcium daily for adults aged 51 and older. For vitamin D, the guidelines are 600 international units (IUs) per day until age 70, and then 800 IUs per day after that. 

And, as I’ve noted here before, those numbers reflect the highest amount that a healthy person would need. And very few people need to take supplements to reach the recommended levels. For example, spending just 5 to 30 minutes outside between 10 a.m. and 3 p.m. twice a week is usually enough to meet most people’s vitamin D requirements — including people living in Minnesota and other northern latitudes.  

Less than 6 percent of Americans are actually deficient in vitamin D, experts say.

Potential harm

Americans spend more than $14 billion each year on vitamin and mineral supplements, despite a steady stream of studies that have shown such supplements offer no benefit to most healthy people and can often be harmful.

Excess amounts of calcium can lead to fatigue, nausea, constipation, headaches and other symptoms, and may cause, over time, the development of kidney stones. One recent study found an association between the use of calcium supplements (but not calcium-rich foods) and an increased risk of developing heart disease. 

Taking too much vitamin D can cause an excessive buildup of calcium in the body.

Last year, University of Minnesota researchers reported that the proportion of proportion of Americans who consume vitamin D supplements at amounts that exceed the recommended limit rose 590 percent between 1999 and 2014.

FMI: You’ll find an abstract of the JAMA study on the journal’s website, but the full study is behind a paywall.

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