Older people unlikely to reduce risk of breaking bones by increasing calcium intake, say new reviews

Older people are unlikely to reduce their risk of breaking a bone by taking calcium supplements or upping their dietary intake, according to two new evidence reviews, which challenge established medical guidelines.

Calcium, found in dairy products, vegetables and nuts, is vital for healthy teeth and bones. According to the NHS, healthy adults need about 700mg a day, which most of us get from our diet.

However,guidelines in the UK and many other countries say older people at high risk of bone fractures should take on at least 1,000mg a day, and are often prescribed supplements to help them reach these levels.

The recommendation is based on calcium’s ability to increase the density of bones. But two studies led by researchers at the University of Auckland in New Zealand, and published in the BMJ on 30 September, say that the effect is small and may not outweigh the risk of taking too much calcium, which has been linked to adverse side effects.

In the first paper, a review of 59 previous trials, researchers found that increasing calcium intake in the diet, or with supplements, only increased bone mineral density by around one to two per cent, which they said was unlikely to lead to “clinically meaningful” protection against fractures.

The second research paper, a review of 72 previous studies, concluded that there is “no evidence currently that increasing dietary calcium intake prevents fractures”. Evidence on supplements was stronger, with the risk of fractures reduced by 11 per cent, but researchers said that this may not be enough to outweigh the risks of taking on too much calcium.

Previous research has suggested links between high calcium intake and constipation, stomach pain and possibly a small increased of more serious cardiovascular problems.

Commenting on the studies in the BMJ, Professor Karl Michaëlsson, of Uppsala University in Sweden, who published research last year suggesting a high milk intake may not cut our risk of breaking a bone, said that the “continued emphasis” on increasing calcium intake to prevent fractures was “puzzling”.

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“The profitability of the global supplements industry probably plays its part, encouraged by key opinion leaders from the academic and research communities,” he said. “Manufacturers have deep pockets, and there is a tendency for research efforts to follow the money (with accompanying academic prestige), rather than a path defined only by the needs of patients and the public.”

He said that 700mg to 800mg of calcium a day was sufficient and questioned guidelines in the USA that recommend higher intakes for the over 50s and are often used to market supplements.

“The weight of evidence against such mass medication of older people is now compelling, and it is surely time to reconsider these controversial recommendations,“ he said.

Guidelines in the UK recommend people with osteoporosis, a bone weakening condition that affects around three million mostly older people, should get 1,000mg of calcium from their diet and may be prescribed supplements if necessary.

Professor Juliet Compston, emeritus professor of bone medicine at the University of Cambridge and a trustee at the National Osteoporosis Society said: ”We already know that calcium supplements increase bone density, but on their own do not reduce fractures. However, a recent analysis concluded that calcium and vitamin D did reduce hip and non-vertebral fractures in postmenopausal women and older men.

“In terms of how much calcium should be recommended, that's difficult but the suggestion in the BMJ's editorial of 700 to 800 mg a day is not supported by any compelling argument - it might be enough, or more might be needed.

Getting around 800 mg of calcium a day through eating a balanced and varied diet is a reasonable level to aim for, although going a bit higher is unlikely to be harmful.”

Dr Carrie Ruxton, a dietician and advisor to the Heath Supplements Information Service, said that the new findings were based on a wide range of studies affecting different groups of people, leading to “uncertainties around conclusion on the relationship of calcium to risk of fracture in different individuals.”