Important Information About Calcium Supplements

Calcium Supplements Questions and Answers

Calcium helps keep your bones strong.

This article was adapted from information on the website of the National Institute of Arthritis and Musculoskeletal and Skin Diseases.

Why Do I Need Calcium?

Calcium is essential for many functions in your body, including the following:

  • regulating your heartbeat
  • conducting nerve impulses
  • stimulating hormone secretions
  • clotting of blood
  • building and maintaining healthy bones

Calcium is a mineral found in many foods.

Getting enough of this nutrient is important because your body cannot make it. Even after you are fully grown, adequate intake of calcium is important because your body loses calcium every day through your:

  • skin, nails, and hair
  • sweat
  • urine and feces

This lost calcium must be replaced daily through your diet. Otherwise, your body takes calcium out of your bones to perform other functions, which can make your bones weaker and more likely to break over time.

Experts recommend that women aged 50 and older get 1,000 to 1,200 mg (milligrams) of calcium each day. Although food is the best source of calcium, most Americans do not get enough calcium from food sources. Calcium-fortified foods (like orange juice, bread, cereals, and many others on your grocer's shelves) and calcium supplements can fill the gap by ensuring that you meet your daily calcium requirement.

What Should I Look for in a Calcium Supplement?

Calcium exists in nature only in combination with other substances.

These substances are called compounds. Several different calcium compounds are used in supplements, including the following:

  • calcium carbonate
  • calcium citrate
  • calcium phosphate

These compounds contain different amounts of elemental calcium, which is 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.

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

  • Does this kind of supplement cause any side effects (like gas or constipation)? If so, you may want to try another kind or a different brand.
  • Is this kind of supplement convenient? Can I remember to take it as often as recommended each day?
  • Is the cost of this supplement within my budget?
  • Is this supplement widely available? Can I buy it at a store near me?

What Other Important Things Should I Consider When Choosing a Calcium Supplement?

Purity: Choose a calcium supplement with a familiar brand name. Look for labels that state "purified" or have the United States Pharmacopeia (USP) 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.

Absorbability: Most brand-name calcium products are easily absorbed 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 and stirring it 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 to 600 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.

Tolerance: 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, you should try another form of calcium.

Also, it is important to increase the dose of your supplement gradually: take just 500 to 600 mg a day for a week, and then slowly add more calcium. Do not take more than the recommended amount of calcium without consulting with your physician first.

Calcium Interactions: It is important to talk with your doctor or pharmacist about possible interactions between your over-the-counter and prescription medications, and calcium supplements. For example, calcium supplements may reduce the absorption of the antibiotic tetracycline.

Calcium also interferes with iron absorption. So you should not take a calcium supplement at the same time as an iron supplement--unless the calcium supplement is calcium citrate. Any medication that you need to take on an empty stomach should not be taken with calcium supplements.

Should I Take a Combination Product?

Calcium supplements are available in a bewildering 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.

Edited by Naveed Saleh, MD, MS, on 12/29/2015.

Getting enough calcium -- whether through your diet or with the help of supplements -- will help to protect the health of your bones. However, this is only one of the steps you need to take for bone health. Exercise, a healthy lifestyle, and, for some people, medication, are also important.

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