Calcium intake does not appear to decrease fracture risk in older patients
A new study indicates that calcium supplements with or without vitamin D do not protect older people in general from fractures, and an editorialist suggests that 700 to 800 mg of dietary calcium daily for adults is probably enough.
Fracture risk in older patients does not seem to be affected by calcium intake, according to 2 recent studies.
In the first study, published online Sept. 29 by BMJ, researchers performed a random-effects meta-analysis of randomized, controlled trials through September 2014 to determine whether increased dietary calcium intake affected bone mineral density (BMD) and whether such an effect was similar to that of calcium supplements. Studies were included if they were randomized, controlled trials of dietary calcium sources or calcium supplements with or without vitamin D; involved patients at least 50 years of age; and used an outcome of BMD at the lumbar spine, total hip, femoral neck, total body, or forearm. Fifteen trials looked at dietary calcium and involved 1,533 patients, and 51 looked at calcium supplements and involved 12,257 patients.
In patients who increased dietary calcium intake, BMD increased by 0.6% to 1.0% at total hip and total body by 1 year and by 0.7% to 1.8% at total hip, total body, lumbar spine, and femoral neck by 2 years. BMD in the forearm showed no effect. With calcium supplements, BMD increased by 0.7% to 1.8% at all of the measured sites at 1, 2, and over 2.5 years, although the increase per year did not change over time. BMD increases were similar in trials that compared calcium alone with calcium plus vitamin D, in trials that compared lower doses of calcium supplementation with higher doses, and in trials that compared higher baseline dietary calcium intake with lower baseline dietary calcium intake. The authors concluded that the increases in BMD seen with increased intake of calcium, through diet or supplements, “are small (1-2%) and non-progressive” and are not likely to have a clinically meaningful effect on fracture reduction.
In the second study, also published online Sept. 29 by BMJ, some of the same authors aimed to assess the evidence supporting current recommendations that older adults should increase calcium intake as a fracture prevention method, as well as whether dietary sources or supplements worked better. They included randomized, controlled trials or cohort studies of dietary calcium, milk or dairy intake, or calcium supplements with or without vitamin D that used fracture as an outcome and looked at patients older than age 50.
Most of the included studies that looked at dietary calcium and dairy intake were cohort studies and found no association between intake and fracture risk. An analysis of 26 randomized, controlled trials found that calcium supplements reduced risk of total fracture and vertebral fracture, but the authors determined that the trial data were biased toward calcium supplements. When they looked at the 4 trials with the lowest risk for bias, involving 44,505 patients, they found no effect of calcium supplementation on fracture risk at any site. The authors concluded, “Overall, there is little evidence currently to suggest an association between calcium intake and fracture risk or that increasing calcium intake through dietary sources will alter risk.”
The author of an accompanying editorial noted that that the available evidence “gives us a strong signal that calcium supplements with or without vitamin D do not protect older people in general from fractures” and said that 700 to 800 mg of dietary calcium daily for adults is probably sufficient. However, he wrote, some groups continue to recommend 1,200 mg of calcium and 800 to 1,000 IU of vitamin D per day for women age 50 and older, amounts that are difficult to reach without supplementation. He called these recommendations “puzzling” in light of the lack of any solid supporting evidence regarding fracture benefit and pointed out that since most older people have calcium and vitamin D intakes below these recommended levels, almost the entire population of adults over age 50 could be considered at risk for fracture.
“Most will not benefit from increasing their intakes and will be exposed instead to a higher risk of adverse events such as constipation, cardiovascular events, kidney stones, or admission for acute gastrointestinal symptoms,” he wrote. “The weight of evidence against such mass medication of older people is now compelling, and it is surely time to reconsider these controversial recommendations.”