This information describes calcium supplements and how to take them.

Calcium is a mineral that is needed to build and maintain healthy bones. If you don’t get enough calcium from your diet, your body will take it from your bones.


Osteoporosis develops when you lose bone tissue, which makes your bones more likely to fracture (break). Osteoporosis is most common in postmenopausal women. However, it can develop in anyone, including men, due to medication or illness. Some risk factors for osteoporosis include:

  • Having a slender build
  • Being of Northern European or Asian descent
  • Having fair skin
  • Going through menopause early (before the age of 45)
  • Taking certain steroid medications for longer than 3 months
  • Not getting enough physical activity
  • Not getting enough calcium in your diet (or from dietary supplements)
  • Smoking
  • Drinking too much alcohol (more than 1 drink per day if you are a woman and more than 2 drinks per day if you are a man)
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Vitamin D

Vitamin D is a vitamin that helps your body absorb calcium. Your body makes vitamin D after being exposed to the sun. Vitamin D is also found in some foods. However, it may be difficult to get enough vitamin D from sunlight and foods alone. Your doctor or dietitian may tell you to take vitamin D supplements. These can be prescription or over-the-counter vitamin D supplement pills, or calcium supplements with added vitamin D.

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Getting enough calcium in your diet helps prevent osteoporosis. Calcium is measured in milligrams (mg) that you need per day. If you are between the ages of 19 and 50, you need 1,000 mg of calcium per day. If you are over 50 years of age, you need 1,200 mg of calcium per day.

Vitamin D is measured in international units (IU) that you need per day. If you are between the ages of 19 and 50, you need 600 IU of vitamin D per day. If you are over 50 years of age, you need 800 IU of vitamin D per day.

If you have osteoporosis, you may need more calcium, vitamin D, or both. Talk with your doctor or dietitian about how much you need per day. Do not take more than your daily recommended amount of calcium because it can be harmful to your health.

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Sources of Calcium


The best way to get calcium is through the food you eat. Dairy products are a good source of calcium. If you are lactose intolerant try lactose-free dairy products. You can also try calcium-fortified orange juice and other foods. Check food labels to see the amount of calcium in foods.

The table at the end of this resource lists some calcium rich foods and beverages.

Calcium supplements

You may find it difficult to get enough calcium from your diet alone. Your doctor or dietitian may suggest that you take a calcium supplement. You do not need a prescription for this. Your doctor or dietitian will tell you how much you should take.

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Types of Calcium Supplements

Two types of over-the-counter calcium supplements are calcium carbonate and calcium citrate. Both are taken orally (by mouth).

Do not buy calcium tablets that are made from bone or dolomite. These may contain lead or other harmful metals. Certain health-food store preparations have this problem. Most calcium supplements that you buy in a pharmacy have been tested for this.

Calcium carbonate

Calcium carbonate is absorbed best if you take it with meals. OsCal® and Caltrate® are 2 brands of calcium carbonate supplements.

Other forms of calcium carbonate include:

  • Some antacids, such as Tums®. If you take Tums®, you do not need to take it with a meal.
  • Viactiv®, which is a flavored soft chew
  • A liquid form that you can usually get from a pharmacy, but may require a special order.

Calcium citrate

Calcium citrate is another type of calcium supplement. Some patients may absorb calcium citrate better than calcium carbonate. This is true for older people, or those with low stomach acid (e.g., pernicious anemia). It is best absorbed if you take it 30 minutes before a meal. One brand of calcium citrate is Citracal®  and it is available in most pharmacies.

If you have any of the following side effects with calcium carbonate, take calcium citrate instead:
  • Abdominal pain
  • Gas
  • Constipation
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Taking Calcium Supplements

  • If you are taking more than 500 mg of calcium supplements per day, take it in divided doses for best absorption. For example, if you take 1,000 mg of calcium each day, take 500 mg in the morning and 500 mg in the evening.
  • Talk with your doctor or dietitian before taking calcium supplements if you:
    • Have a history of hypercalcemia (too much calcium in the blood)
    • Take diuretics (water pills) or antacids for indigestion
    • Have ever had kidney stones
    • Have had problems with your parathyroid glands
    • Have a history of heart disease, including heart attack or stroke
  • If you are taking a bisphosphonate medication for osteoporosis (or for other reasons), take your calcium supplement at least 30 minutes after you take it. If you are not sure if the medication that you are taking is a bisphosphonate, talk with your doctor. Some examples of bisphosphonate medications are alendronate (Fosamax®) and risedronate (Actonel®). Please note that calcium supplements do not replace other medications for the treatment of osteoporosis.
  • Calcium supplements can cause constipation. If you have this side effect, increase the amount of liquids and fiber in your diet. If that doesn’t work, talk with your doctor or nurse about taking a stool softener or laxative, or try to get more calcium from foods rather than supplements.
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Calcium-Rich Foods and Beverages:

The following list includes some foods and beverages that are rich in calcium.

Food Portion size Calcium in portion (mg) Calories in Portion
Parmesan cheese 1½ ounces 503 167
Cheddar cheese 1½ ounces 307 171
Milk, low-fat 1 cup (8 ounces) 305 102
Yogurt, plain, nonfat 1 cup (8 ounces) 265 150
Soy milk, plain, calcium-fortified 1 cup (8 ounces) 301 80
Sardines, canned in oil, with bones, drained 2 sardines 92 50
Collards, cooked ½ cup 134 31
Bok choy (Chinese cabbage), raw 1 cup 74 9
Almonds ¼ cup 96 207
Figs, fresh 2 medium figs 35 74
Mineral water (eg, San Pellegrino®, Perrier®) 1 cup (8 ounces) 33 0

If you would like more information on foods that are rich in calcium, please ask to speak with a dietitian.

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National Institutes of Health
Osteoporosis and Related Bone Diseases ~ National Resource Center
202-223-0344 or (800)-624-BONE

National Osteoporosis Foundation

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If you have any questions or concerns, talk with a member of your healthcare team. You can reach them Monday through Friday from 9:00 am to 5:00 pm at ____________________. After 5:00 pm, during the weekend, and on holidays, please call____________________. If there’s no number listed, or you’re not sure, call 212-639-2000.
Calcium Supplements
©2016 Memorial Sloan Kettering Cancer Center - Generated on May 31, 2016