Researchers from the University of Auckland in New Zealand and the University of Aberdeen in Scotland looked at data from the trials in which a total of 12,000 people aged over 40 taking calcium supplements of 500mg or more a day took part.
It was the effect of supplements, which increased the levels of calcium circulating in the blood and caused the increased risk, they pointed out. “Given the modes benefits of calcium supplements on bone density and fracture prevention, a reassessment of the role of calcium supplements in the management of osteoporosis is warranted,” they said.
The researchers said those who had a diet naturally high in calcium were at no increased danger.
The study in the British Medical Journal recommends that doctors review their use of calcium supplements for managing osteoporosis.
Medical director of the Well Woman Centre, Dr Shirley McQuade, said none of the trails that were analysed had deliberately set out to look at heart disease, so information was not collected in any standardised form.
“Differences arising from relatively small numbers should be interpreted with caution,” she warned yesterday.
Dr McQuade said an American study, conducted several years ago, looked at the effect calcium supplements have on heart disease.
Researchers who monitored 34,500 people over an eight-year period found no change in the heart disease risk.
Dr McQuade said women, in particular, tended to take calcium supplement to protect bone density because they were more likely than men to develop osteoporosis, which increases their risk of bone fracture, especially wrist, vertebrae and hip.
Good sources of dietary calcium included dairy products, soya and fish, she pointed out.
Dr McQuade said calcium supplements were advisable where someone was found to have a low bone density.
“Perimenopausal women have also been shown to require higher level of calcium than either before or after the menopause so it is important that if they have any dietary restrictions, calcium supplements should be considered,” she said.
“From a bone healthy point of view, the best form of supplement is where calcium is combined with vitamin D.
“Interestingly, the authors of this week’s study restricted their analysis to studies that had calcium only. Previous studies on calcium and vitamin D have not shown any detrimental effect on the heart” she said.
“So my advice to women in the perimenopause is to have a high dietary intake of calcium and, if this is not possible, then add a supplement that contains calcium and vitamin D,” she said.
Dr McQuade said people diagnosed with osteoporosis should continue to take their calcium and vitamin D supplement, along with whichever osteoporosis treatment they have been prescribed.”
President of the Irish Osteoporosis Society, Prof Moira O’Brien, speaking on RTÉ radio yesterday, said calcium should always be administered with vitamin D so the body could absorb it.