Calcium supplements

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Calcium supplements

Information

WHO SHOULD TAKE CALCIUM SUPPLEMENTS?

Calcium is an important mineral for the human body. It helps build and protect your teeth and bones. Getting enough calcium over your lifetime can help prevent osteoporosis, which is sometimes called thin bones.

Many people get enough calcium in their normal diet. Dairy foods, leafy green vegetables, and calcium fortified foods have high levels of calcium. For example, 1 cup or 237 milliliters (mL) of milk or yogurt has 300 milligrams (mg) of calcium. Older women and men may need extra calcium to prevent them from getting osteoporosis.

Your health care provider will tell you if you need to take extra calcium. The decision to take extra calcium should be based on balancing the benefits and risks of doing so.

TYPES OF CALCIUM SUPPLEMENTS

Forms of calcium include:

Calcium carbonate. Over-the-counter (OTC) antacid products contain calcium carbonate. These sources of calcium do not cost much. Each pill or chew provides 200 mg or more of calcium. This form of calcium should be taken with meals.
Calcium citrate. This is a more expensive form of calcium. It is absorbed well on an empty or full stomach. People with low levels of stomach acid (a condition that is more common in people over age 50) absorb calcium citrate better than calcium carbonate.
Other forms, such as calcium gluconate, calcium lactate, calcium phosphate: Most have less calcium than the carbonate and citrate forms and do not offer any advantages over them.

When choosing a calcium supplement:

Look for the word purified or the United States Pharmacopeia (USP) symbol on the label.
Avoid products made from unrefined oyster shell, bone meal, or dolomite that do not have the USP symbol. They may have high levels of lead or other toxic metals.

HOW TO TAKE EXTRA CALCIUM

Follow your provider's advice on how much extra calcium you need.

Increase the dose of your calcium supplement slowly. Your provider may suggest that you start with 500 mg a day for a week, and then add more over time.

Try to spread the extra calcium you take over the day. Do not take more than 500 mg at a time. Taking calcium throughout the day will:

Allow more calcium to be absorbed
Cut down on side effects such as gas, bloating, and constipation

The total amount of calcium adults need every day from food and calcium supplements:

19 to 50 years: 1,000 mg/day
51 to 70 years: Men - 1,000 mg/day; Women - 1,200 mg/day
71 years and over: 1,200 mg/day

The body needs vitamin D to help absorb calcium. You can get vitamin D from sunlight exposure to your skin and from your diet. Ask your provider whether you need to take a vitamin D supplement. Some forms of calcium supplements also contain vitamin D.

SIDE EFFECTS AND SAFETY

Do not take more than the recommended amount of calcium without your provider's approval.

Try the following if you have side effects from taking extra calcium:

Drink more fluids.
Eat high-fiber foods.
Switch to another form of calcium if the diet changes do not help.

Always tell your provider and pharmacist if you are taking extra calcium. Calcium supplements may change the way your body absorbs some medicines. These include certain types of antibiotics and iron pills.

Be aware of the following:

Taking extra calcium over a long period of time raises the risk of kidney stones in some people.
Too much calcium can prevent the body from absorbing iron, zinc, magnesium, and phosphorus.
Antacids have other ingredients such as sodium, aluminum, and sugar. Ask your provider if antacids are OK for you to use as a calcium supplement.

References

Cosman F, de Beur SJ, LeBoff MS, et al. Clinician's guide to prevention and treatment of osteoporosis. Osteoporos Int. 2014;25(10):2359-2381. PMID: 25182228 www.ncbi.nlm.nih.gov/pubmed/25182228/.

US Preventive Services Task Force; Grossman DC, Curry SJ, et al. Vitamin D, calcium, or combined supplementation for the primary prevention of fractures in community-dwelling adults: US Preventive Services Task Force recommendation statement. JAMA. 2018;319(15):1592-1599. PMID: 29677309 www.ncbi.nlm.nih.gov/pubmed/29677309/.

Weber TJ. Osteoporosis. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 225.

Review Date: 1/1/2025
Reviewed By: Linda J. Vorvick, MD, Clinical Professor Emeritus, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Editorial update 06/02/2025.

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