Previously thought to help prevent heart disease and stroke, calcium supplements have now been shown to almost double the risk of heart attack, and doctors are warning that such supplements should be taken with caution.

The finding is based on a large scale study of 23,980 men and women in Heidelberg, Germany. They were part of a cancer and nutrition study, but the results allowed researchers to assess how calcium supplements were linked to heart disease as well.

Researchers from Zurich University's institute of social and preventive medicine found that people who used calcium supplements regularly were 86% more likely to suffer a heart attack than those who didn't.

Those who obtained their calcium just from supplements were 2.7 times more likely than non-users to experience a heart attack.

Most take calcium supplements for bone growth, but this new research points out that such action should be taken only under close consultation with a doctor. Dr Claire Bowring, of the UK's National Osteoporosis Society, explained to the Guardian:
"This study further highlights the need for care when considering taking calcium supplements. If you get all of the calcium that you need from your diet then a supplement will not be necessary. Boosting calcium beyond recommended levels has no extra benefit for bones.

"Supplementation may be warranted if you are unable to get enough calcium in your diet, but it needs to be done with consideration."
Do consult your doctor first. Check out the report published in the journal Heart. [Heart via The Guardian]