Calcium and Vitamin D Supplements May Increase Heart Disease Risk

Many women take a calcium supplement after menopause. Studies have been carried out to evaluate the effect of these supplements on women’s health. This report reanalyzed the data collected by several such studies to understand how calcium with or without vitamin D affects cardiovascular health in women. It examined four heart-related problems and their combinations in a seven-year-long study of 36,282 women. Some women took other calcium supplements than what was prescribed to them as a part of the study, which too was included in the analysis. The calcium supplementation seems to increase the risk of a heart attack.

Calcium supplements, with or without vitamin D, are widely used for the prevention and treatment of osteoporosis. Higher incidences of heart-related problems are reported in women who take calcium supplements. Analysis of several studies showed that when calcium was given without vitamin D, the risk of heart attack increased. In a study involving 36,282 women, it was found that 53 percent of women were taking calcium supplement and 47 percent of women were taking vitamin D on their own. However, such uncontrolled intake of the two supplements confuses the outcome of the results. The current study examines the effect of calcium supplements, with and without vitamin D, on cardiac problems in a controlled environment.

* Results from the Women’s Health Initiative Calcium/Vitamin D Supplementation Study (WHI CaD Study) were analyzed on the basis of four outcomes: heart attack, need for a bypass, death from cardiac arrest and stroke. The combinations of these four outcomes were also considered in this analysis.
* Electrocardiograms were conducted to determine silent heart attacks.
* Baseline values for weight and dietary intake of calcium were previously recorded and were measured again, when the study was conducted.
* The results from the WHI CaD Study and two smaller studies were pooled for the analysis.

* In this study, 54 percent participants took calcium supplements at random and 47 percent participants took vitamin D supplements, both at their personal initiative. The results show that there is a correlation between calcium and vitamin D intake and cardiovascular disease (stroke, etc.).
* In calcium + vitamin D group, women who did not take personal calcium were at a higher risk of cardiac disease than women who did take personal calcium. This was independent of dietary calcium and the dose of personal calcium.
* Clinical data for women taking calcium supplements and vitamin D were similar to those who took just vitamin D.
* The results shows that treatment with calcium and/or vitamin D leads to more strokes and myocardial blockage, than in preventing fractures. Many women take these supplements to prevent fractures.
* Although the increase in cardiac disease in women taking calcium (without/with vitamin D) is moderate, it becomes significant because of the large portion of the population that takes it.

Shortcomings/Next steps
This study was based on a publicly accessible dataset and relied totally on the information provided in this dataset. This included false positive final results that were prone to over-interpretation. For getting the most accurate comparisons, various end points were prespecified. Some studies involved younger participants and some studies considered obesity as a factor affecting the results. All this added to the complexity of the interpretations in this study.

The intake of calcium (in small or large doses) and vitamin D supplement may increase the chances of cardiovascular problems in older women. The increased calcium in blood plasma might be the reason for this, resulting in calcification of the circulatory system, making the blood vessels less flexible. This is similar to the effects of a hyperactive thyroid gland, which raises calcium levels in the blood. The sudden increase in blood calcium may also affect coagulation events in the blood. Addition of vitamin D to the calcium supplement does not seem to change these observations significantly. It is recommended that prescribing additional calcium to postmenopausal women should be re-examined.

For More Information:
Calcium Supplements with or without Vitamin D and Risk of Heart Problems: Reanalysis of Studies on Women’s Health
Publication Journal: BMJ, 2011
By Mark Bolland; Andrew Grey; University of Auckland, New Zealand

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