Taking calcium supplements to boost bone density or prevent fractures as people get older does not work, according to major research.
But two studies published in the British Medical Journal Wednesday say there is no evidence increasing calcium intake through supplements prevents fractures and they should not be recommended.
Most people should get enough calcium through a normal diet, they conclude. Foods rich in calcium include dairy products, vegetables such as broccoli and cabbage, soya beans, nuts, and anything made with fortified flour.
The National Health Service in the UK says adults need 700mg of calcium a day, and does not recommend supplements of it, though older people are advised to boost their Vitamin D. But some doctors and international organizations recommend higher calcium intakes in order to improve bone density and prevent fractures.
In the new studies, scientists in New Zealand looked at the effect of diet and supplements on bone health in people aged over 50. The first study found that increasing calcium intake from dietary sources or by taking supplements produced small (1-2 per cent) increases in bone mineral density, which “are unlikely to lead to a clinically meaningful reduction in risk of fracture”.
The second found there was no evidence from clinical trials that increasing dietary calcium intake prevented such breaks.
In an editorial, Prof Karl Michaelsson, from Uppsala University in Sweden, said: “The official recommendations in the UK and Nordic countries of 700-800 mg/day of dietary calcium for adults seem at present to be enough. This intake can be achieved with a normal varied diet.
“Other guidelines such as from the US National Osteoporosis Foundation promote at least 1,200 mg calcium and 800-1000 mg IU vitamin D daily as a goal for women aged 50 or older. Few women can achieve these intakes through dietary means alone.”
Calcium supplements are often prescribed along with vitamin D for the estimated three million people with osteoporosis. Yet research published in the BMJ in 2011 found that taking daily calcium supplements of 1g plus vitamin D increased the risk of heart attacks by 20 per cent.
Researchers said it was “puzzling” that organizations such as the International Osteoporosis Foundation continued to promote intakes that were so high most people over the age of 50 would need to take a supplement.
“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,” Prof Michaelsson said.
He also suggested “the profitability of the global supplements industry probably plays its part” in some of the advice to take supplements.
A spokesman for the Health Supplement Information Service said: “It is important to note that there were disparities in the calcium supplementation trial methodologies which make comparisons between trials and hence conclusions difficult. Fourteen of the 26 trials studied calcium alone, eight studied calcium and vitamin D, and four were multi-arm or factorial studies of both agents.
“In addition, the majority did not take vitamin D status into account; calcium cannot be absorbed or utilized without vitamin D and there is a wealth of evidence to suggest that a combination of these nutrients is effective for reducing the risk of both fracture and falls.”