Calcium supplements may raise the risk of dementia among women who have had a stroke, a new study has suggested.
The supplements are recommended to women with osteoporosis to help prevent bone fractures.
The study, published in the journal Neurology, followed 700 women aged 70 to 92 who were initially all free of dementia. They were asked about their use of medicines and supplements and tested for dementia again after five years. Some had brain scans to look for signs of cerebrovascular disease — specifically, white matter lesions, or areas of poor blood flow on the brain — which is associated with vascular dementia.
It found that the women who had suffered strokes were seven times more likely to develop dementia if they took the supplements.
Women who had not had a stroke but whose brains showed signs of cerebrovascular disease were also three times more likely to develop dementia than those not taking the supplements.
However, researchers stressed that the study was very small and that more work was needed into the findings. Of the 700 women, only 98 took calcium supplements and just 14 of these developed dementia.
Two studies last year found that, for most healthy people, calcium supplements make little difference to bone health or your risk of breaking a bone. However, the studies looked at people aged over 50 rather than specifically those treated for brittle bones.
The UK government says that for most people a healthy diet (including milk and cheese, nuts, bread and green leafy vegetables such as broccoli and cabbage) is sufficient to meet our need for calcium.
This study suggests that more research is needed on calcium supplements. It does not suggest, as some newspapers stated, that you should ‘avoid calcium supplements if you want to escape the peril of dementia’.
The study was an observational one, which means that it wasn’t a trial as such. This has many drawbacks, including the inability to control potentially important influencing variables. In addition to this, the sample size is very small — only 98 subjects were actually taking calcium supplements. The authors themselves were conscious of these issues and were open about them in their write-up. The way the mainstream media have reported this, though, has the potential to frighten people about medication they may need.
Research score: 1/5