Here’s What You Need to Know:

  • Calcium supplementation is a very common practice. 
  • Recent evidence shows that long-term calcium intake in high doses from supplements may do more harm than good.   
  • There is an increased risk of heart attacks and strokes seen in those taking calcium supplements.
  • Supplementing with calcium increases blood levels too rapidly, leading to increased probability of blood clotting and deposition of calcium in arteries, leading to their blockage.
  • This risk is not seen when calcium is taken from food maybe because the calcium from food is released more slowly.  

Calcium plays a key role in the biology of the human body. Besides its celebrated role in the development of bones and teeth, calcium is involved in processes like nerve signal transmission, blood circulation and hormone release. 

Calcium is among the most commonly used supplements, with most users citing “bone health” as the main reason for using it.

Calcium supplements are available in the form of tablets, capsules, powder and effervescent tablets. 

Meeting the recommended intake of calcium is important as a deficiency would lead to the body using its reserves from bone and teeth, leaving them weaker. 

Calcium and Increased heart disease risk

Calcium supplementation has recently come under fire after studies found that the potential benefits are countered by a number of drawbacks (1), namely a:

►17% higher risk of getting kidney stones.

►20-40% increase in the risk of heart attacks.

►12-20% increase in the risk of stroke.

What is the available evidence?

Researchers from the US Cancer Research Institute tracked 219059 men and 169170 women over 12 years and found that men who took more than 1000mg/ day of calcium via supplements had a 20% higher risk of total cardiovascular death than participants taking no Calcium (2).

This is probably caused by the deposition of calcium in the coronary arteries when intakes are too high, a phenomenon known as Coronary artery calcification (CAC). 

The Journal of the American Heart Association recently published a study (3) (2016) that assessed the link between the risk of CAC and calcium intake, showed that, after 10 years of follow-up, calcium supplement use was associated with increased risk for CAC. 

How does this happen?

A possible explanation is that calcium supplements may acutely elevate calcium levels in blood. 

The increased calcium levels can favour blood clotting as calcium is an important clotting factor. Acute increases in calcium levels can also cause the deposition of calcium in blood vessels, leading to a hardening of the arteries. Both these effects increase the risk of heart disease. 

It has been suggested by some experts that taking Vitamin D, which increases the absorption of Calcium, can reduce the potential risk.

It must be noted that the consumption of foods rich in calcium was found to not increase the cardiovascular risk (4), which suggests that nutritional intake should be prioritized 

It must be noted that the addition to the supplement protocol of Vitamin D, known to help calcium absorption, did not help (5, 6)


About the Author

Veeraj Goyaram, MSc (Med) Exer. Sci (UCT) cum laude, BSc (Hons) Biology.

Veeraj’s passion revolves around researching and developing nutritional products for optimal health and performance, with a particular interest in sports, child and diabetic nutrition products. Veeraj was previously a graduate student at the University of Cape Town, where he examined the effect of exercise and nutrition on the function of genes in muscle. His research was published in renowned scientific journals and medical textbooks on Diabetes and Exercise (PubMed listing). Veeraj keeps healthy by regularly lifting weights and taking daily walks.



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