Two studies by a group of researchers from New Zealand have reviewed clinical studies of calcium intake and risk of fracture in the participants over the age of 50, challenging current guidelines
Dietary guidelines currently recommend increasing calcium intake or taking calcium supplements to between 1000-1200mg per day in an effort to reduce risk of fracture associated with osteoporosis in people over the age of 50. However, there has been conflicting data from clinical trials to support the benefits, while there is a growing concern regarding the risks of taking calcium supplements, including risk of cardiovascular events.
The first study reviewed clinical evidence regarding the recommended guidelines of increasing calcium intake, either through increased dietary intake or by taking supplements, in an effort to prevent fractures in participants over 50 years of age. The review found that dietary calcium intake was not associated with fracture. In trials assessing calcium supplements, there was some evidence of a reduction in risk of fracture, however the researchers reported some bias in these studies. From the available clinical evidence, the researchers concluded that increasing intake of calcium through diet or via supplements is not associated with fracture risk. They found inconsistent evidence for the role of calcium supplements in prevention of fractures in this population.
The same group of researchers then also assessed clinical evidence for the role of calcium intake from dietary sources on bone mineral density, in comparison with calcium supplements in participants over 50 years of age. They found that bone mineral density was increased by up to 1.8% after 2 years, with increased calcium intake from either dietary sources, or supplements. From this second study the researchers concluded that increased calcium from either diet or supplements increased bone mineral density, however, that this increase in bone mineral density is not likely to translate into clinically relevant reductions in risk of fracture. The results of the two studies call into question the current recommendations for calcium intake in this population.
Bolland, MJ, Leung, W, Tai, V, Bastin, S, Gamble, GD, Grey, A, Reid, IR “Calcium intake and risk of fracture: systematic review” BMJ 2015;351:h4580
Tai, V, Leung, W, Grey, A, Reid, IR, Bolland, MJ “Calcium intake and bone mineral density: systematic review and meta-analysis” BMJ 2015;351:h4183
Written by Deborah Tallarigo, PhD