Calcium supplements may increase MI risk
By Lilian Anekwe
Calcium supplementation may increase the risk of myocardial infarction, according to a team of international researchers who have warned their findings may have major implications for osteoporosis treatment.
Calcium supplements, along with vitamin D, are recommended in NICE guidance on osteoporosis and are commonly prescribed for other musculoskeletal conditions, as well as women on hormone replacement therapy and long-term users of corticosteroids.
But a meta-analysis of five randomised controlled trials of more than 8,000 patients followed for a median of 3.6 years, found 143 people allocated to daily calcium supplements of 500mg or more had a myocardial infarction compared with 111 on placebo. Overall, calcium increased the risk of a myocardial infarction by 31% compared to those on a placebo.
There was also non-significant 20% increase in the incidence of stroke amongst patients on calcium supplements, and non-significant increases in death and a composite endpoint of myocardial infarction, stroke or sudden death of 18% and 9% respectively. The data was presented at the World Congress on Osteoporosis in Florence.
The researchers only looked at patients who took calcium supplements on their own, but argued that their evidence should prompt a ‘reassessment' of the use of calcium in patients with osteoporosis.
Dr Mark Bolland, head of the osteoporosis research group at the University of Auckland, concluded: ‘Calcium supplements without co administration of vitamin D are associated with an increased risk of myocardial infarction.
‘As calcium supplements are widely used, these modest increases in risk of cardiovascular disease might translate into a large burden of disease and a reassessment of calcium in the management of osteoporosis is warranted.'
Dr Steve Longworth, a GP in Leicester and former president of the Primary Care Rheumatology Society, said: ‘Current guidance says to prescribe alendronate along with a calcium and vitamin D supplements to people with osteoporosis. So this news is not welcome.
‘If the risk persists for calcium and vitamin D combinations then that's something that will clearly be a worry. So until manufacturers come up with a vitamin D on its own we will have to warn our patients that it might increase their risk of a heart attack. It will be difficult to explain that and present that in a balanced way, especially to elderly patients.'
Osteoporosis International 2010; 21:S21Calcium, vitamin D and cardiovascular events
• Calcium supplementation has been shown to improve lipid profiles, leading some to expect a beneficial effect on CVD
• But in 2007 data from the Women's Health Initiative showed a trend towards more MIs in women taking calcium
• This new analysis suggests a significant association between calcium supplements and MI risk
• It's thought higher calcium intake- particularly as a bolus – may be accelerating calcium deposition in coronary artery walls
• It's unclear whether calcium plus vitamin D could carry the same risk
• But trial data suggests moderate to high vitamin D intake reduces the risk of CVD