People aged over the age of 50 should take calcium tablets to reduce their risk of bone damage, reported The Guardian . Taking pills every day could prevent one in four fractures from falls, the newspaper reported. Taking supplements “reduced the risk of fractures by 12% but when the proper dose of 1,200mg was taken every day the risk was reduced by 24%”, it stated.
The research is a well-conducted study examining the effects of calcium supplements across multiple trials.
Where did the story come from?
The research was carried out by Benjamin Tang and colleagues at the University of Western Sydney, University of Sydney and Deakin University, Australia. The study received funding from the Australian Government and was published in the peer-reviewed medical journal The Lancet .
What kind of scientific study was this?
The researchers undertook a systematic review of randomised controlled trials. They looked at trials from 1966 onwards that had investigated the use of calcium supplements, or of calcium in combination with vitamin D, to prevent fractures and loss of bone mineral density (osteoporosis) in people over 50.
The study did not look at trials that tested calcium from dietary sources, or trials that combined calcium with other treatments that may be used in the prevention of osteoporosis such as hormones or bisphosphonate drugs.
In these trials the researchers looked for the result of a fracture occurring at any site, such as spine, hip or wrist. Seventeen trials (with 52,625 participants) were included. The results from these were combined to calculate the overall effect of calcium treatment.
What were the results of the study?
The majority of participants in the trials were women (92%). Overall, the researchers found that taking calcium, or calcium plus vitamin D tablets reduced the risk of fracture by 12% compared with taking a placebo. They found that the risk of fracture was reduced even more (by 24% – the one in four figure reported in the news) in the trials where more people took the correct dose of medication, and took it as frequently as they had been asked to. The effect also seemed to increase by taking higher doses of both calcium and vitamin D.
What interpretations did the researchers draw from these results?
The researchers concluded that “calcium supplementation, alone or in combination with vitamin D, is effective in the preventative treatment of osteoporotic fractures”. They say that in people over the age of 50, a minimum daily dose of 1,200mg calcium is recommended, and if vitamin D is also used in combination, 800 units (IU) is recommend. They highlight the fact that people need to take the supplements regularly and in appropriate dosages to achieve maximum benefit.
What does the NHS Knowledge Service make of this study?
This research involved a large number of people and was generally reliable and well conducted. There are a few points to consider when interpreting these findings, as the researchers themselves acknowledge.
- These trials involved mostly women because fractures are a common problem in postmenopausal women, due to hormonal changes which result in the weakening of bones. Therefore, no reliable conclusions can be made about the effects of calcium supplementation in men.
- People who have weakening of bones from specific causes, such as from long-term steroid use, have not been examined by this research, therefore the effects of calcium supplementation in these people is not known.
- Conclusions cannot be drawn about the effects of calcium supplementation in younger people, as this study only looked in trials in people aged 50 and over.
- Importantly, however, no mention has been made of the side effects or risks from excessive calcium intake in certain people. Care must be taken when recommending that all people over the age of 50 take extra calcium. Most people can absorb adequate calcium through a healthy and balanced diet, although there are times when additional supplements are needed, such as in childhood or pregnancy or if there is impaired absorption in the gut, as may occur in old age or with other intestinal conditions. Just as there are known problems from having too little calcium in the body, there are also serious risks from having an excess amount of calcium, such as may occur in certain medical conditions, e.g. kidney diseases, certain cancers, or in people with increased secretion of parathyroid hormone. In such cases, extra calcium would be inadvisable.
Sir Muir Gray adds...
This may be the best evidence we will get until a very large trial of vitamin D supplementation is funded. For most people, it looks as though extra calcium and vitamin D reduce the rate at which bones thin and therefore reduce the risk of a fracture occurring.
Analysis by Bazian
Edited by NHS Website
Links to the headlines
The Guardian, 24 August 2007
Links to the science
Lancet 2007; 370:657-666