Calcium supplementation may not benefit older adults according to two new studies in The BMJ. Calcium supplementation has been under scrutiny because of side effects such as increased cardiovascular risk and kidney stones. Now, new research suggests that calcium has minimal to no benefit on bone mineral density (BMD) or fractures. Researchers performed a meta-analysis of 59 studies of dietary calcium or calcium supplementation involving almost 14,000 patients. Increased dietary calcium augmented BMD by 0.6-1.0% at the total hip and total body at 1 year and by 0.7-1.8% at these sites as well as the lumbar spine and femoral neck at 2 years. There was no effect on the forearm BMD. Calcium supplements increased BMD by 0.7-1.8% at all five skeletal sites at 1, 2, and more than 2.5 years, but the size of the increase in BMD at later points in time was similar to the increase at 1 year. Adding vitamin D to calcium did not make a difference. The authors concluded that increasing calcium intake from dietary sources or supplements produces small, non-progressive increases in BMD, which are unlikely to make a clinically significant reduction in fracture (BMJ 2015;351:h4183).
In a different study in the same issue of The BMJ, researchers examined studies of dietary calcium intake, most of which were cohort studies of dietary intake of calcium, milk, or dairy. Most studies showed no association between calcium intake and fracture. Some randomized studies of calcium supplementation showed only a modest benefit for total fractures (relative risk [RR], 0.89; 95% confidence interval [CI], 0.81-0.96) and vertebral fractures (RR, 0.86; CI, 0.74-1.00) but no benefit for hip or forearm fractures. Analysis showed some bias toward calcium supplementation in the cohort studies, whereas there was no effect on fracture at any site in the randomized, controlled trials, with less risk of bias. The authors concluded that “Dietary calcium intake is not associated with risk of fracture and there is no clinical trial evidence that increasing calcium intake from dietary sources prevents fracture. Evidence that calcium supplements prevent fractures is weak and inconsistent” (BMJ 2015;351:h4580). An accompanying editorial suggests that most adult > 50 years of age will not benefit from increasing calcium intake but will be exposed to a higher risk of adverse events, such as constipation, cardiovascular events, kidney stones, or admission for acute gastrointestinal symptoms. “The weight of evidence against such mass medication of older people is now compelling, and it is surely time to reconsider these controversial recommendations” (BMJ 2015;351:h4825).
