What Impairs the Absorption of Calcium

Some things impair absorption of calcium, so more calcium must be ingested in the diet to make up for what is not being absorbed.

• Corticosteroids: Corticosteroid therapy, such as prednisone, taken for longer than 6 weeks, an extra 300-500 milligrams of calcium should be consumed a day (or a total of 1500 milligrams daily).



• Sodium: Sodium increases the amount of calcium that is excreted in the urine, so if eating foods high in salt, more calcium should be consumed.



• Excess protein: The body uses excess protein for energy. However, as protein is burned for energy, it produces sulfate. Sulfate increases the amount of calcium excreted in the urine, which decreases the amount of calcium in the body. Excess protein creates excess sulfate.



• Oxalate: Found in some foods and beverages, most notably spinach, chard, berries, chocolate, and tea, oxalate binds with calcium and increases the loss of calcium through fecal excretion. For example, even though sweet potatoes contain calcium, not all of it is absorbed because of the oxalic acid (oxalate) that is also in them.



• Phosphorous: Also known as phosphoric acid and phosphate, phosphorous, which is in cola and many processed foods, can interfere with calcium absorption.



• Insoluble fiber: This type of fiber, such as the kind in wheat bran, reduces calcium absorption.



• Alcohol intake: Drinking excessive amounts of alcohol can interfere with the calcium balance by inhibiting the enzymes that convert inactive vitamin D to active vitamin D.



• Caffeine: Excessive intake of caffeine (300-400 mg) can increase urinary excretion as well as fecal excretion. (One cup [8 fl oz] of brewed coffee contains about 137 mg of caffeine.)



• Smoking, stress, and lack of exercise: These lifestyle factors contribute to the body not being able to absorb calcium as efficiently.