What Every Woman Needs to Know about the Dangers of Calcium Supplements

by Stacy Facko


Most calcium supplements are composed of calcium carbonate, a poorly absorbed and counter-productive form of this mineral.  One study even found that this form of calcium also had an “unavoidable presence of aluminium” (1).

Derived primarily from limestone, high amounts in the form of antiacids are responsible for causing calcificaiton, constipation, as well as heartburn and acid reflux, the exact symptoms it is meant to address!

Why is this?

The main reason is that by taking calcium carbonate, it counteracts the acid in the stomach over time, so the individual produces less acid, and could experience worse heartburn than before supplementation. Excess calcium, without the presence of magnesium, leads to calficiation of arteries, and tissues. (2).

But Calcium helps Bones right?

Unfortunately, the most commonly used form. Calcium carbonate was found in some studies to have no effect on osteoporosis, but increased the risk of heart attacks in women. It also can cause kidney stones, hypercalcemia and calcification of arteries. Another study found that calcium supplementation increase risk of hip fracture, and an increase in heart disease (3).

It has also been found to lower thyroid function and even block T3 utilization, the active thyroid hormone that control heart rate, metabolism, digestion and mental wellbeing.

What is the best Form?

One of the best forms of calcium is dicalcium malate, which has a better solubility for absorption, and integration into the body’s biochemical processes, leading to less negative effects.

If you absolutely have to take calcium, two things are important to remember:

  • Ensure it is from food or food sourced supplements, or a natural form like dicalcium malate
  • Take it with magnesium, which aids absorption while preventing the negative effects on the arteries

See Dr. Clark's magnesium and calcium products here.

Other Supplements Even More Important for Bone Health:

  • Boron
  • Vitamin D
  • Vitamin K





  1. EFSA Panel on Food Additives and Flavourings (2023) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10373136/
  2. Reid, I. R., Bolland, M. J., Avenell, A., & Grey, A. J. O. I. (2011). Cardiovascular effects of calcium supplementation. Osteoporosis International, 22, 1649-1658.
  3. The good, the bad, and the ugly of calcium supplementation: a review of calcium intake on human health. Li K, Wang XF, Li DY, Chen YC, Zhao LJ, Liu XG, Guo YF, Shen J, Lin X, Deng J, Zhou R, Deng HW. Clin Interv Aging. 2018 Nov 28;13:2443-2452






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