Calcium Supplements - What You Need to Know

Which Calcium Supplement Should You Take?

Caltrate pills
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Calcium is essential for many body functions, including regulating the heartbeat, conducting nerve impulses, stimulating hormone secretions, clotting of blood, and building and maintaining healthy bones. Calcium is a mineral found in many foods. Getting enough of this nutrient is important because the human body cannot make it. Even after you are an adult, adequate calcium intake is important because the body loses calcium every day through the skin, nails, hair, sweat, urine and feces.

The lost calcium must be replaced daily through the diet. Otherwise, the body takes calcium out of the bones to perform other functions, making the bones weaker and more likely to break over time.

Experts recommend that adults get 1,000 to 1,200 mg of calcium each day. Although food is the best source, most Americans do not get enough calcium from food sources. Supplements and calcium-fortified foods can provide additional calcium.

Elemental Calcium

Calcium exists in nature only in combination with other substances.Several different calcium compounds are used in supplements, including calcium carbonate, calcium phosphate, and calcium citrate. These compounds contain different amounts of elemental calcium (the actual amount of calcium in the supplement). It is important to read the label carefully to determine how much elemental calcium is in the supplement and how many doses or pills to take.

Choosing a Calcium Supplement

Calcium supplements are available without a prescription in a wide range of preparations and strengths, which can make selecting one a potentially confusing experience. Often, people ask which calcium supplement they should take. The best supplement is the one that meets your needs, so ask yourself these questions:

  • How well does my body tolerate a calcium supplement?
  • Does it cause any side effects?
  • Is it convenient?
  • Can I remember to take calcium as often as recommended each day?
  • Is the cost within my budget?
  • Is it widely available?

Choose calcium supplements with familiar brand names. Look for labels that state purified or have the USP (U.S. Pharmacopeia) symbol. Avoid calcium from unrefined oyster shell, bone meal, or dolomite without the USP symbol, because it may contain high levels of lead or other toxic metals.

Most brand-name calcium products are absorbed easily in the body. If you are not sure about your product, you can find out how well it dissolves by placing it in a small amount of warm water for 30 minutes (stirring occasionally). If it hasn’t dissolved within this time, it probably will not dissolve in your stomach. Chewable and liquid calcium supplements dissolve well because they are broken down before they enter the stomach.

Calcium, whether from food or supplements, is absorbed best by the body when it is taken several times a day in amounts of 500 mg or less, but taking it all at once is better than not taking it at all.

Calcium carbonate is absorbed best when taken with food. Calcium citrate can be taken anytime.

For certain people, some calcium supplements may cause side effects, such as gas or constipation. If simple measures (such as increasing your intake of fluids and high-fiber foods) do not solve the problem, try another form of calcium. Also, it is important to increase the dose of your supplement gradually: take just 500 mg a day for a week, then slowly add more calcium. Don't take more than the recommended amount of calcium without your doctor’s approval.

Calcium Interactions

It is important to talk with a doctor or pharmacist about possible interactions between your over-the-counter and prescription drugs, and calcium supplements. For example, calcium interferes with iron absorption (don't take a calcium supplement at the same time as an iron supplement - unless the calcium supplement is calcium citrate, or unless the iron supplement is taken with vitamin C). Medications taken on an empty stomach should not be taken with calcium supplements.

Combination Products

Calcium supplements are available in an array of combinations with vitamins and other minerals. Calcium supplements often come in combination with vitamin D, which is necessary for the absorption of calcium. However, calcium and vitamin D do not need to be taken together and/or in the same preparation in order to be absorbed by the body. Minerals such as magnesium and phosphorus also are important but usually are obtained through food or multivitamins. Most experts recommend that nutrients come from a balanced diet, with multivitamins used to supplement dietary deficiencies. Getting enough calcium, whether through your diet or with the help of supplements, will help to protect the health of your bones.

Calcium and Inflammatory Conditions

Calcium supplements are typically taken to prevent osteoporosis. This is especially the case for people with rheumatoid arthritis and other inflammatory types of arthritis. As well as being at an increased risk of developing osteoporosis, rheumatic disease patients may be treated with corticosteroids which also increase the risk of osteoporosis.


Calcium and Vitamin D: Important at Every Age. May 2015.

Primer on the Rheumatic Diseases. Thirteenth edition. Springer. Page 699. Calcium. Accessed 02/06/16.

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