What Type of Calcium Supplement Is Best?

calcium supplement
Calcium can be found in a variety of foods. Michael Grimm / Getty Images

Question: What type of calcium supplement is best?

Answer: There are many types of calcium supplements, including calcium carbonate, calcium citrate, calcium gluconate, and others. Calcium exists as a compound, that's why it is found in these forms. However, some people debate whether or not one particular type of calcium is better than another.

Is one type of calcium supplement better?
Less important than the type of calcium supplement is the amount of elemental calcium within the supplement. Depending on the manufacturer, they may list the amount of elemental calcium directly on the label, or they may list the weight of the calcium tablet itself.

The better way to check for the amount of elemental calcium the supplement contains is by looking at the RDA. The RDA for most individuals is 1000 mg of calcium per day (this varies, by age, gender, and special situations including pregnancy). If the bottle states a tablet contains 40% of the RDA of calcium, then it contains 400 mg of elemental calcium.

Calcium carbonate contains the highest concentration of elemental calcium (about 40% by weight), followed by calcium citrate (about 20% by weight).

What about oyster shell calcium?
Some forms of calcium supplements have been found to contain toxins including lead. These include oyster shell, dolomite, and bone meal. Therefore, these types of supplements should be avoided.

How is calcium best absorbed in the body?

  • Meals
    • Different types of calcium require different scenarios to be absorbed into the body. Calcium carbonate should be taken with meals. Calcium citrate should be taken on an empty stomach.
  • Medications
    • Calcium should not be taken with medications including antibiotics, iron supplements, and other medications. Calcium can bind to these medications and diminish the absorption. Check with your pharmacist about medication interactions.
  • Vitamin D
    • Calcium is best absorbed when taken with Vitamin D. Many supplements are produced with both calcium and Vitamin D included.
  • Dose
    • Calcium should be taken in divided doses, rather than all at once. Separate doses into twice or three times daily for optimal absorption.

So which type of calcium supplement is best?

Different types are better for different people. Read the recommendations for when a supplement you are considering should be taken, and consider if that fits into a reasonable schedule for you. Look at the amount of elemental calcium contained in the supplement, and ensure you would be consuming an adequate dose.

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