Calcium Supplements May Increase Risk Of Heart Attack In Older Women
Featured ArticleMain Category: Cardiovascular / Cardiology
Also Included In: Women's Health / Gynecology; Nutrition / Diet; Bones / Orthopedics
Article Date: 16 Jan 2008 - 11:00 PDT
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Researchers in New Zealand have discovered that calcium supplements may increase the risk of heart attack in healthy postmenopausal women.
The study is published online today, Wednesday 16th January, in the British Medical Journal (BMJ) and is the work of researchers at the University of Auckland.
Calcium supplements are often prescribed to women past their menopause as a way to keep bones healthy, and some doctors believe it can also prevent arteries clogging up by lowering circulating levels of bad cholesterol.
However, the evidence is scanty, so the researchers at the University of Auckland's Faculty of Medical and Health Sciences decided to investigate the effect of calcium supplementation on myocardial infarction, stroke, and sudden death in healthy postmenopausal women.
They did this by carrying out a secondary analysis of an existing randomized placebo controlled trial in an urban-situated academic medical centre in New Zealand, involving 1,471 postmenopausal women over 55 and of average age 74 who were randomly assigned to receive a calcium supplement or a placebo.
The original study was looking at the effect of calcium on bone fracture. The women were also asked questions about calcium in their diet, and they were assessed every six months for five years.
The researchers worked out that including the daily supplement, women in the calcium group were getting on average about 1,861 milligrams (mg) of calcium a day, while those in the placebo group, who got their daily calcium only from their diet, averaged about 853 mg a day.
The main outcome measures noted in the study were the following cardiovascular-related events: death, sudden death, angina, myocardial infarction (heart attack), chest pains, stroke, transient ischaemic attack (mini stroke).
The results showed that:
- Reports of myocardial infarction (heart attack) were significantly higher in the calcium group than in the placebo group (45 events in 31 women versus 19 events in 14 women).
- The occurrence of any three vascular events, myocardial infarction, stroke, or sudden death was also significantly more common in the calcium group (101 events in 69 women versus 54 events in 42 women).
- Because the results were so important, the researchers went back and checked hospital records and death certificates to look for any unreported events.
- After adjusting the figures for the newly found and previously unreported events, they discovered that myocardial infarction (heart attack) was still more common in the calcium group (36 events in 31 women versus 22 events in 21 women on placebo).
- The figures for heart attack, stroke or sudden death also went up in the calcium group (76 events in 60 women versus 54 events in 50 women on placebo) but were shown to have borderline significance.
"Calcium supplementation in healthy postmenopausal women is associated with upward trends in cardiovascular event rates."
However they cautioned against rash treatment decisions by saying that:
"This potentially detrimental effect should be balanced against the likely benefits of calcium on bone." This was particularly important in the case of elderly women they said.
According to an article in WebMD today, a US expert said the findings could be a "fluke" and were not weighty enough to warrant changing any current treatments involving calcium supplements.
"Vascular events in healthy older women receiving calcium supplementation: randomised controlled trial."
Mark J Bolland, P Alan Barber, Robert N Doughty, Barbara Mason, Anne Horne, Ruth Ames, Gregory D Gamble, Andrew Grey, Ian R Reid.
BMJ 2008:394405257
published online, 15 January 2008.
doi:10.1136/bmj.39440.525752.BE
Click here for Article.
Sources: BMJ article, Newswise press release, WebMD.
Written by: Catharine Paddock
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today
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Visitor Opinions In Chronological Order (3)
Facing Reality
posted by dr maurice mckeown on 16 Jan 2008 at 11:05 pmIt is interesting that research studies providing evidence contrary to current views are labelled as flukes. Those providing results which support current ideas are hailed as dramatic new evidence confirming the status quo.
Highlighting the flaws with this meta-analysis
posted by The Right Supplements on 31 Jul 2010 at 1:47 pmThere are several issues with this study which make it irrelevant to responsible supplement users.
First, the authors of the meta-analysis purposely excluded any studies which included vitamin D supplementation with the calcium. We know that vitamin D deficiency increases risk for cardiovascular problems. The studies examined revealed that subjects had very low vitamin D blood levels; ranging from a mere 18.0 - 37.2 ng/dl, far below the optimal range of 60 - 80 ng/dl.
Next, there was zero mention of vitamin K supplementation in any of the studies analyzed. Respected organizations have long suggested supplementation with vitamin K along with your calcium to promote healthy arteries. Adequate vitamin K is required to ensure sufficient carboxylation of matrix-GLA protein. If Matrix-GLA protein is undercarboxylated, it can build up in the arteries and form what is commonly referred to as "arterial calcification".
Lastly, it is unfortunate that the media is now, because of this meta-analysis, portraying calcium in such a negative light. Many direct-intervention studies have shown that calcium supplementation positively impacts many parameters affecting cardiovascular health, including body weight, blood pressure and cholesterol levels.
If Calcium Supplementation poses a risk, why not for supplemented foods?
posted by Gary Syme on 18 Aug 2010 at 6:26 pmAre all foods safe from the possible problem with calcium supplements through their slower delivery of calcium? A number of popular milks have added Calcium Carbonate. Whereas the calcium naturally occurring in milk is bound to the proteins, surely the "supplementation" of unbound calcium offers the same risk - assuming of course that there is a risk.
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