A high calcium intake may be linked to women facing an increased risk of serious heart disease, researchers warned today.
The use of calcium supplements has become common, and more than 60% of middle aged and older women in the US are regular users of calcium supplements, say Dr Karl Michaelsson of Uppsala University, Sweden, and colleagues in the British Medical Journal.
They aimed to investigate a link between long term high calcium intake and death from all causes, as well as heart disease. Figures came from 61,433 women born between 1914 and 1948, and followed for about 19 years.
During this time, there were 11,944 deaths from all causes, 3,862 from cardiovascular disease, 1 932 from ischaemic heart disease, and 1,100 from stroke. Calcium intake was estimated based on food and supplement questionnaires.
Compared with calcium intakes between 600 and 1,000 mg/day, intakes above 1,400 mg/day were linked with higher death rates from all causes – a rise of about 40%. Cardiovascular disease was raised by 49% and the risk of ischaemic heart disease was more than doubled. But no link was seen with stroke.
Raised death rates were also seen among women with an intake below 600mg/day.
"Among calcium tablet users with a dietary calcium intake above 1,400 mg/day the hazard ratio for all cause mortality was more than doubled," write the authors.
They suggest that: "Diets that are low or very high in calcium can override normal homeostatic control causing changes in blood levels of calcium or calciotropic hormones [involved in calcium regulation]."
Too much calcium may trigger higher levels of "fibroblast growth factor 23", they believe, which is linked to cardiovascular events and deaths from all causes.
* A second study yesterday linked the pain-killer diclofenac to heart problems.
Writing in PLoS Medicine, researchers said the evidence was so strong the drug should not be prescribed.
British experts said it was a drug that should be prescribed "with caution."
Maureen Talbot, of the British Heart Foundation, said: "The risks associated with non-steroidal anti-inflammatory painkillers, which include diclofenac, have been known for some years and they should always be prescribed with caution.
"Anyone taking these painkillers should be made aware of both their risks, especially of cardiovascular disease and internal bleeding, and benefits in treating debilitating pain such as that caused by arthritis."
Michaelsson, K. et al. Long term calcium intake and rates of all cause and cardiovascular mortality: community based prospective longitudinal cohort study. BMJ 13 February 2013 doi: 10.1136/bmj.f228 [abstract]
McGettigan P, Henry D. Use of Non-Steroidal Anti-Inflammatory Drugs That Elevate Cardiovascular Risk: An Examination of Sales and Essential Medicines Lists in Low-, Middle-and High-Income Countries. PLoS Med 10(2): e1001388. doi:10.1371/journal.pmed.1001388
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