Do Calcium Supplements Cause Heart Disease?

 

Submitted by Amy Sercel MS RD CD

Edited By Marcia Bristow MS RCN CSSD CD

It was all over the news: a study published in the Journal of the American Heart Association found that “calcium supplements are bad for your heart”¹ and people should avoid taking them.  This is pretty scary considering that almost half of American adults take some type of calcium supplement.^2,3 Before you stop taking your supplement altogether, remember that this is only one study and that the media tends to exaggerate scientific findings to spark the most interest in their stories. 

The researchers looked at data from 2,742 people who participated in the Multi-Ethnic Study of Atherosclerosis.  They believed that taking calcium supplements could cause calcium to be deposited in the arteries, causing the arteries to harden and leading to heart disease.  The results are complicated.

• For the participants who already had calcium in their arteries at the beginning of the study, taking supplements did not affect their risk of heart disease.⁴
• People who had the lowest total calcium intake and took supplements were at the highest risk for developing heart disease.^2,4 
• People with the highest calcium intake (more than 1,400 mg per day from either food or supplements) had the lowest risk of developing heart disease.^2,3
• Regardless of total calcium intake, people who took supplements were 22% more likely to develop heart disease than those who did not.^2,3

It’s important to note that this study only found a correlation between supplements and heart disease.  A correlation or association occurs when two things change at the same time but may not be related.   For example, there may be a correlation between ice cream sales and shark attacks during the summer, but that does not mean buying ice cream will result in a shark attack.  On the other hand, causation occurs when one event leads to another and can only be proved by randomized trials.  This study compared calcium supplementation with accumulation of calcium in the arteries and did not involve giving people calcium supplements to see whether they developed heart disease.  Therefore, the findings cannot actually prove that taking calcium supplements causes heart disease.  

 It’s possible that the people who took supplements had a lower quality diet overall or another lifestyle factor that contributed to their risk for heart disease.  This study’s findings also conflict with other research.  An expert panel of Tufts University researchers examined 165 peer-reviewed articles and 11 systematic reviews on the topic and found that there is no relationship between calcium supplements and heart disease.⁵ In fact, a study of 38,772 women found that a calcium intake below 696 mg per day was associated with an increased risk of heart disease and that calcium supplements lowered that risk.^6,7

So, what does this all mean?  Although this one study found a relationship between calcium supplements and heart disease, the overall body of literature does not agree.  While it is always a good idea to get your nutrients from food sources, taking calcium supplements to meet your needs is a safe way to make up any deficits in your diet.^4,5 It’s important to make sure you are meeting your needs for calcium each day to maintain bone, nerve, and muscle health.  The recommended daily intake of calcium is 1,200 mg for women and 1,000 mg for men.  Foods rich in calcium, such as dairy products, leafy green vegetables, fortified cereals, and fatty fish canned with bones, are valuable parts of a healthy meal plan and are also good sources of other essential nutrients.  If you are worried about your calcium intake, talk to a Registered Dietitian to see if you should make any dietary changes.

References:

1.         Calcium supplements could increase risk of heart disease, new study finds - The Washington Post. https://www.washingtonpost.com/national/health-science/calcium-supplements-may-raise-risk-of-heart-disease/2016/10/17/a80285fe-9215-11e6-9c52-0b10449e33c4_story.html?utm_term=.2050a130d1aa. Accessed December 1, 2016.

2.         Anderson JJB, Kruszka B, Delaney JAC, et al. Calcium Intake From Diet and Supplements and the Risk of Coronary Artery Calcification and its Progression Among Older Adults: 10‐Year Follow‐up of the Multi‐Ethnic Study of Atherosclerosis (MESA). J Am Heart Assoc. 2016;5(10):e003815. doi:10.1161/JAHA.116.003815.

3.         Calcium supplements may damage the heart. ScienceDaily. https://www.sciencedaily.com/releases/2016/10/161011182621.htm. Accessed December 1, 2016.

4.         Schardt D. See the news that calcium supplements are bad for your heart? NutritionAction.com. October 2016. http://www.nutritionaction.com/daily/dietary-supplements/see-the-news-that-calcium-supplements-are-bad-for-your-heart/. Accessed November 22, 2016.

5.         Kopecky SL, Bauer DC, Gulati M, et al. Lack of Evidence Linking Calcium With or Without Vitamin D Supplementation to Cardiovascular Disease in Generally Healthy Adults: A Clinical Guideline From the National Osteoporosis Foundation and the American Society for Preventive Cardiology. Ann Intern Med. October 2016. doi:10.7326/M16-1743.

6.         Vitamin D and calcium: a systematic review of health outcomes. http://www.crd.york.ac.uk/CRDWeb/ShowRecord.asp?ID=32010001604. Accessed November 22, 2016.

7.         Mursu J, Robien K, Harnack LJ, Park K, Jacobs DR. Dietary supplements and mortality in older women: the Iowa Women’s Health Study. Arch Intern Med. 2011;171(18):1625-1633. doi:10.1001/archinternmed.2011.445.