J Cell Biochem. 2014 Dec 10. doi: 10.1002/jcb.25028. [Epub ahead of print]
Reid IR1, Bristow SM, Bolland MJ.
1University of Auckland, Auckland, New Zealand; Department of Endocrinology, Auckland District Health Board, New Zealand.
There is longstanding concern that calcium supplements might increase cardiovascular risk in patients with renal impairment.
The Auckland Calcium Study suggested that the same problem occurs in older people taking these supplements for prevention of osteoporosis.
Our subsequent meta-analyses, (which followed protocols finalized before the data was available) confirmed that calcium supplements, with or without vitamin D, adversely affected risk of myocardial infarction and, possibly, stroke.
Several groups have re-visited these data, consistently finding an adverse effect of calcium on myocardial infarction, not always statistically significant because some meta-analyses have been under-powered.
Whether or not an adverse effect of calcium plus vitamin D on myocardial infarction is found depends on whether two specific groups of subjects are included - those in the Women's Health Initiative who were already taking calcium at the time of randomization, and subjects from an open, cluster-randomized study in which baseline cardiovascular risk was different between groups.
Vitamin D alone does not affect vascular risk, so it is unlikely that differences between calcium alone and calcium plus vitamin D are real, and they are more likely to result from the inclusion of studies at high risk of bias.
The mechanisms of the adverse cardiovascular effects are uncertain but may be mediated by the increase in serum calcium following supplement ingestion, and the effects of this on vascular function and coagulation. Available evidence suggests the risks of calcium supplements outweigh any small benefits on fracture incidence, so the case for their use is weak.
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- Pages listed in BOTH the categories Cardiovascular and Calcium
- Calcium Supplementation is OK provided you also take Vitamin K – Feb 2019
- Less than 900 IU of Vitamin D and Calcium do not cause cardiovascular problems – Dec 2016
- 800 IU of vitamin D is not enough to help Cardiovascular Disease (found again) – Oct 2016
- Calcium supplementation associated with 3.9X increase risk of atrial fibrillation – June 2015
- Adding Calcium does NOT cause cardiovascular problems (reverses their meta-analysis) – Dec 2014
- Increased Vitamin K2 reduces the problems of excess Calcium – Nov 2013
- More than 400 mg of Calcium supplements caused cardiovascular deaths in men - Feb 2013
- Stiff arteries in seniors associated with low vitamin D levels – July 2012
- Aortic Calcification 85 percent more likely if vitamin D level lower than 29 ng – June 2012
- More than 800 mg of Calcium increases Cardiovascular events by 85 percent– Nov 2011
- Is excess calcium harmful to health - 2010
- Review of Calcium – Vitamin D - Cardiovascular Disease – June 2011
- Calcium without vitamin D increased heart risk by 30 percent - Jan 2011
- Heart attacks increased by 30% in those taking 500 mg of Calcium without vitamin D – July 2010