Can calcium supplements increase risk of heart attacks in older women?
Publication Date:15/01/2008
Introduction
Older women who take calcium supplements may be at increased risk of having a heart attack, a study suggests. However the researchers stress that the findings, although important, are not definite and that more research is needed.
What do we know already?
Women who have been through the menopause are often advised to take calcium supplements (usually with vitamin D) to help keep their bones strong and protect them from fractures.
Some studies have found that postmenopausal women who have higher levels of calcium in their blood (either because they take supplements or because they get more calcium through their diet) have healthier cholesterol levels and a lower risk of heart and circulation problems. For this reason some doctors think that calcium supplements may also protect against problems such as heart attacks, strokes and angina.
But there have been problems with the research. Some studies were not very good quality, while others had mixed results in postmenopausal women. This makes it difficult to draw any firm conclusions about the benefits of taking calcium in this group of women.
The present research was done to try to get better quality information on the effects of calcium on the hearts and circulation of postmenopausal women.
What does the new study say?
The new study looked at 1,471 postmenopausal women aged 55 or over who took either one gram of calcium every day or a dummy treatment (placebo). The average age of the women was 74. The women were seen every six months over five years. They were asked about their diet and any health problems they had had. The study found that there were more heart attacks among the women who took calcium. Women who took calcium were also more likely to have either a heart attack, a stroke or to die suddenly.
Tell me more about the study's findings
Because the findings of the study could have important implications for postmenopausal women, the researchers checked hospital records and death certificates for any important health problems among the women that may not have been reported. When they added these events to their findings they found that:
- Heart attacks were still more common in women who took calcium supplements. Out of 58 heart attacks altogether 62% (36) were among women who took calcium.
- Women who took calcium were more likely to have a heart attack, a stroke or to die suddenly. Out of 130 events 58% (76) were among women who took calcium.
But the differences in the number of heart attacks, strokes and deaths, between women who took calcium and women who didn't, was small. This means that more research is needed before we can be sure of the results.
Where does the study come from?
The study was done by researchers from the University of Auckland in New Zealand. It was published in the online version of the British Medical Journal.
How reliable are the findings?
There were some problems with this study, which makes it less reliable. It was quite a small study. Fewer than 1,500 women were included and altogether there were just 58 heart attacks over five years. Also all the women were over 55 (the average age was 74) and white so the findings might not apply to younger women and those from different racial groups.
But the study was a good quality study. A study of the same group of women had already shown that calcium supplements can help to keep bones strong. This shows that the type of calcium supplements used were being taken up by the body and having an effect.
What does this mean for me?
If you're a woman who has been through the menopause and you are either taking calcium supplements or thinking of taking them to maintain bone health, then you may be concerned about the results of this study. But it's important to note that the results are not definite and that bigger studies are needed to find out for certain what the effect of calcium on heart attacks and strokes is. It's also important to note that the results of this study don't apply to younger women (the average age in the study was 74), or to women from different ethnic groups.
You need to remember that heart attacks and strokes are linked to a number of definite risk factors. These include smoking, high blood pressure, high cholesterol, diabetes, close family history of a heart attack and obesity.
What should I do now?
If you're already taking calcium you may be doing so for a very good reason. For example, you may be at higher risk of bone fractures and your doctor has advised you to take them. It is important to note that the authors of this study point out that this study is not conclusive. You may wish to discuss this matter further with your doctor, at your next routine appointment, especially if you have some known risk factors for heart attack or stroke. However, your doctor may still advise you that the potential benefits of taking calcium supplements in your case outweigh the potential risks.
There are several things you can do yourself to reduce your risk of heart attack and stroke. They include taking regular exercise, keeping to a healthy diet, not smoking and drinking alcohol in moderation.
From:
Bolland MJ, Barber PA, Doughty RN, et al. Vascular events in healthy older women receiving calcium supplementation: randomised controlled trial. British Medical Journal. 2008. Online first at http://www.bmj.com.
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This information does not replace medical advice. If you are concerned you might have a medical problem please ask your Boots pharmacy team in your local Boots store, or see your doctor.
