In a disturbing study, it was revealed that subjects who took calcium supplements appeared to be twice as likely to suffer hearts attacks as those who took no supplements. This has been reported by all the usual media outlets, and this site always leans toward favoring calcium from natural food sources rather than from pills. Still, for a more balanced look at this issue, we need go no farther than the National Health Service in the UK. Their website provides a very balanced picture of the story. For example…
These headlines are based on the findings of a large German study that looked at the association between calcium intake and incidents of heart attack, strokes and deaths from cardiovascular disease over a period of 11 years.
Calcium supplements are often given to elderly people and women who have gone through the menopause, in an effort to keep their bones healthy.
Researchers found no link between the amount of calcium in people’s diet and their risk of stroke or cardiovascular deaths. However, people using calcium supplements as their only form of supplement had more than twice the risk of heart attack compared with people who didn’t take any vitamin supplements.
Note first that they said there is no link between the amount of calcium in ones diet and heart attacks. This is about supplements, not calcium rich foods. Also, this seems confined to comparing those who take calcium and no other supplements with those who take no supplements at all. It could be supplement usage that’s the issue here. More…
The researchers believed that people who take supplements may be generally less healthy than those who don’t (assuming they take supplements for a health reason) so they tried to adjust for other risk factors such as smoking habits and exercise levels. However, it is unlikely they adjusted for all the influencing factors and so we still cannot be certain that calcium supplements increase heart attacks.
Previous research based on stronger study designs has also supported a link between calcium supplements and heart disease. If you are considering taking calcium supplements, you need to base your decision on your own circumstances, balancing the benefits with the potential risks.
Do not be alarmed by the media headlines. If you have been prescribed calcium supplements do not stop taking your medication. Speak to your doctor if you have particular concerns.
Again, good advice. But the waters are muddy. On to the conclusion of the NHS:
This large prospective cohort study following more than 23,000 German adults over 11 years showed that those regularly taking only calcium supplements were at a higher risk of heart attack compared with those not taking supplements.
This study has many strengths, including its large size and its prospective nature over a relatively long period of 11 years.
However, while this study does highlight an association, it doesn’t prove that calcium supplementation causes more heart attacks. There are potentially other factors, some measured in the study and some not, which could influence the link between calcium supplementation and incidence of heart attack.
For example, compared with non-users, the study reported that those taking calcium supplements only were more likely to:
- be older
- be less well-educated
- have smoked for longer
These are all factors that could contribute to poorer heart health. However, the people taking calcium supplements only were also more likely to be:
- physically active
- a healthy weight
These are all factors that promote good heart health. This contradiction highlights that there can be many fundamental differences between people who use calcium supplements and those who don’t. Not all of these differences will have been taken into account in the statistical analyses of the results and so some uncertainty remains as to how strong the association is.
However, there have been several randomised controlled trials of calcium supplements and their effect on heart disease, which have shown similar results to the current study. Taken together, these studies strengthen the link between calcium supplements and heart disease. But supplements are often taken for good reasons and so it is important for health professionals to help to determine whether the potential risks of taking calcium supplements outweigh the benefits for each individual.
If you have been prescribed calcium supplements, don’t be alarmed by the headlines. Don’t stop taking your medication, but speak to your doctor if you have particular concerns.
Or just take the advice of Linda Russel, a nutritionist quoted in USA today:
“Walk into any drugstore and these calcium supplements just jump off the shelves at you. But by taking foods high in calcium four times a day, you should get all that you need.”