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Calcium supplements increase the risk of stroke by 15-20% according to 9 studies
Friday, February 03, 2012 10:32 am Email this article
Calcium supplements increase the risk of stroke by 15-20% according to a meta-analysis of 9 studies. (The risk varied from 15-20% depending on which trials they analyzed and how.)
However, the total risk of death during the durations of these studies was only 1% greater in those taking a calcium supplements, and this difference was not statistically significant, that is, it could have been due to random chance.
Does the Dose of Calcium Matter?
The dose of calcium did not matter; even small doses (less than 500 mg) were associated with an increase in heart attacks
They did not find any dose-related effect.
That is, even small doses of calcium—less than 500 mg—increase the risk of heart attacks just as much as dose of more than 1000 mg.
“When the personal calcium supplement users were divided into three groups by daily supplement intake (1–499, 500–999, and ≥1000 mg/day), there was no evidence of a relation between the dose of personal calcium supplements and the risk of cardiovascular events,” the paper notes.
They also found no difference in whether people were given calcium alone or calcium plus vitamin D.
“There were no significant three-way interactions between calcium and vitamin D,” the authors wrote.
“We repeated these analyses in the subgroup of women not using personal calcium supplements and found no interactions between calcium and vitamin D… for any cardiovascular end point,” they continued.
Conclusion #1: Calcium with or without Vitamin D increase the risk of heart attacks (and stroke)
“When these results are taken together with the results of other clinical trials of calcium supplements, with or without vitamin D, they strongly suggest that calcium supplements modestly increase the risk of cardiovascular events, particularly myocardial infarction,” the authors concluded.
Conclusion #2: Perhaps older people should NOT take calcium supplements
They went on to question whether or not older people should be taking calcium supplements.
“These data justify a reassessment of the use of calcium supplements in older people.”
Other Evidence Supporting This Idea
Elevated levels of blood calcium are associated with heart attack and and increased risk of death
They also note that other research has found that elevated levels of calcium are associated with an increased risk of heart attack and death.
“If calcium supplements do increase cardiovascular risk it is important to consider the potential underlying mechanisms,” the authors note.
“Calcium supplements acutely increase serum calcium concentration by a modest amount, an effect that is sustained during long term treatment, as evidenced by lower levels of parathyroid hormone.
“Serum calcium concentrations are positively associated with
- carotid artery plaque thickness
- aortic calcification
- incidence of myocardial infarction (heart attack)
- and mortality.
“These findings are consistent with observational data suggesting increased risk of cardiovascular events and death in primary hyperparathyroidism, a condition in which serum calcium concentration is elevated.”
Bolland MJ, Grey A, Avenell A, Gamble G, Reid I. Calcium supplements with or without vitamin d and risk of cardiovascular events: Reanalysis of the women’s health initiative limited access dataset and meta-analysis. BMJ. 2011, 342:d2040.
AUTHOR’S CONTACT INFORMATION
Department of Medicine, University of Auckland, Private Bag 92 019, Auckland 1142, New Zealand.
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