Does Calcium Cause Constipation?

It has not been scientifically proven that either dietary calcium or calcium supplements would cause constipation. However, some people complain about constipation after eating dairy products (which are high in calcium), taking calcium supplements or other medications containing calcium.

On the other hand, elevated level of calcium in the blood serum (hypercalcemia) does cause constipation (1).

Constipation as a Side Effect of Calcium Containing Medications

The following calcium containing medications mention constipation as a possible side effect:

  • Calcium supplements, like calcium carbonate or citrate (oral), or calcium chloride (intravenous)
  • Acid lowering drugs (tums): calcium carbonate

Hypercalcemia can cause dehydration and decreased contractions of the gut muscles both of which can result in constipation (2). Medications that do not contain calcium, but can cause hypercalcemia, if overdosed (1):

  • Vitamin D
  • Vitamin A
  • Parathormone (PTH)
  • Lithium, used in treatment of manic/depressive (bipolar) disorder 
  • Theophylline, used in treatment of asthma and COPD (bronchitis and emphysema) 
  • Thiazide diuretics 

Is Constipation Caused by Foods Rich in Calcium?

1. Dairy Products

Milk or yogurt can be constipating for some, especially for children, and when taken in large quantities (3). It can cause lose stools in others, especially those with lactose intolerance. Some people take yogurt to prevent constipation… Rarely, consumption of large quantities of milk and acid lowering drugs containing calcium carbonate or baking soda can lead to milk alkali syndromewith hypercalcemia, kidney pain, excessive urination, fatigue and constipation (4).

Cheese can be constipating due to its lack of dietary fiber and low water content, rather than due to its calcium content.

Kefir cultured milk (KCM), fermented for 36-48 hours may be constipating. 

2. Other Foods Rich in Calcium

Examples of foods rich in calcium (5):

  • Figs
  • Rhubarb
  • Salmon
  • Sardines, tinned, if eaten with bones
  • Tofu, soybean
  • Whitebait

Except tofu, none of above foods is known to cause constipation. It is soybean protein in tofu rather than calcium that may cause constipation.

Summary

Dietary calcium and calcium supplements may cause constipation in some people, but not in all. Hypercalcemia from any cause, including overdose of calcium supplements (more likely intravenous than oral), can cause constipation.

Related Articles:

References:

  1. Hypercalcemia causes constipation  (emedicine.medscape.com)
  2. Why does hypercalcemia cause constipation?  (cancer.gov)
  3. Milk and yougurt can cause constipation in children  (keepkidshealthy.com)
  4. Milk-alkali syndrome and constipation  (emedicine.medscape.com)
  5. Foods rich in calcium  (iofbonehealth.org)