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Calcium

calcium Calcium is the most prevalent mineral in the human body. About 99% of the body's calcium resides in the bones and teeth, and the remaining 1% is dispersed throughout other body fluids and cells.

Functions

Calcium's functions include:
  • Builds bones, both in length and strength
  • Helps bones remain strong by slowing the rate of bone loss with age
  • Helps muscles contract
  • Helps the heart beat
  • Plays a role in normal nerve function, transfers nerve impulses
  • Helps blood clot during bleeding
  • Builds healthy teeth (in kids)

Recommended Intake

The Institute of Medicine offers these recommendations:
Age Group
(in years)
Recommended Dietary Allowance or •Adequate Intake (mg/day)
Females Males
Birth to 6 months 200 milligrams (mg) 200 mg
7-12 months 260 mg 260 mg
1-3 years 700 mg 700 mg
4-8 years 1,000 mg 1,000 mg
9-18 years 1,300 mg 1,300 mg
19-50 years 1,000 mg 1,000 mg
51-70 years 1,200 mg 1, 000 mg
71 years and older 1,200 mg 1,200 mg
Pregnant or lactating teens 1,300 mg n/a
Pregnant or lactating adults 1,000 mg n/a

Calcium Deficiency

In childhood, not getting enough calcium may interfere with growth. A severe deficiency may keep children from reaching their potential adult height. Even a mild deficiency over a lifetime can affect bone density and bone loss, which increases the risk for osteoporosis.
If you do not consume enough calcium, your body will draw from the storage in your bones in order to supply enough calcium for its other functions: nerve transmission, muscle contraction, heartbeat, and blood clotting.
Symptoms of a calcium deficiency include:
  • Intermittent muscle contractions
  • Muscle pain
  • Muscle spasms
  • Numbness or tingling in the hands and feet
  • Rickets in children
  • Osteoporosis in adults

Calcium Toxicity

Very large doses over a prolonged period of time may cause kidney stones and poor kidney function. Your body may not absorb other minerals, such as iron , magnesium , and zinc , properly. These problems could occur from consuming too much through a calcium supplement, not from milk or other calcium-rich foods. The tolerable upper intake level (UL) depends on age.
Age Group
(in years)
Upper Level Intake (mg/day)
Females Males
Birth to 6 months 1,000 milligrams (mg) 1,000 mg
7-12 months 1,500 mg 1,500 mg
1-8 years 2,500 mg 2,500 mg
9-18 years 3,000 mg 3,000 mg
19-50 years 2,500 mg 2,500 mg
51 years and older 2,000 mg 2,000 mg
Pregnant or lactating teens 3,000 mg n/a
Pregnant or lactating adults 2,500 mg n/a

Major Food Sources

Dairy foods—milk, yogurt, and some cheeses—are the best dietary sources of calcium. These foods are also rich in vitamin D, which helps the body absorb calcium.
Food Serving size Calcium content
(mg)
Yogurt 1 cup 300-400
Milk 1 cup 300-400
Macaroni and cheese, homemade 1 cup 362
Parmesan cheese 1 Tbsp 336
Eggnog, nonalcoholic 1 cup 330
Chocolate milk 1 cup 300
Ricotta cheese ½ cup 300
Powdered milk ¼ cup 290
Cheddar cheese 1 ounce 250
Swiss cheese 1 ounce 250
Provolone cheese 1 ounce 215
Cheese pizza 1/6 frozen pizza 210
Mozzarella cheese 1 ounce 175
American cheese 1 ounce 160
Cottage cheese 1 cup 120
Frozen yogurt, soft serve ½ cup 100
Ice cream ½ cup 80
Absorption of calcium from some other dietary sources is not as great as that from dairy foods. Specifically, dark green vegetables contain oxalates, and grains contain phytates, which can bind with calcium and decrease their absorption.
Read food labels to determine the specific calcium levels of these foods.
Food Serving size Calcium content
(mg)
Tofu, regular, processed with calcium ½ cup 435
Calcium-fortified soy milk 1 cup 250-300
Salmon, canned with edible bones 3 ounces 212
Calcium-fortified orange juice ¾ cup 200
Blackstrap molasses 1 Tbsp 172
Pudding, from cook & serve mix ½ cup 150
Dried figs 5 pieces 135
Tofu, regular (processed without calcium) ½ cup 130
Anchovies with edible bones 3 ounces 125
Turnip greens, boiled ½ cup 100
Milk chocolate bar 1.5 ounce 85
Okra, boiled ½ cup 77
Tempeh ½ cup 77
Kale, boiled ½ cup 70
Mustard greens, boiled ½ cup 65
Orange 1 medium 50
Pinto beans ½ cup 45

Health Implications

Bone Health and Osteoporosis Prevention

Calcium is essential to build and maintain strong bones at all stages of life. Bone growth begins at conception, and bones grow longer and wider until well into the 20s. After this type of growth is complete, bones gain in strength and density as they continue to build up to peak bone mass by about age 35. From this point on, as a natural part of the aging process, bones slowly lose mass. Calcium is essential to slow this natural loss and stave off the onset of osteoporosis—a disease in which bones become fragile and more likely to break.

Tips for Increasing Your Calcium Intake

  • When making oatmeal or other hot cereal, use milk instead of water.
  • Add powdered milk to hot cereal, casseroles, baked goods, and other hot dishes.
  • Make your own salad dressing by combining low-fat plain yogurt with herbs.
  • Add tofu (processed with calcium) to soups and pasta sauce.
  • If you like fish, eat canned fish with bones on crackers or bread.
  • For dessert, try low-fat frozen yogurt, ice cream, or pudding.
  • In baked goods, replace half of the fat with plain yogurt.

Taking Supplements

If you are unable to meet your calcium needs through dietary sources, consider a calcium supplement. Some points to remember when choosing and using a calcium supplement include:
  • Check the label because the amount of calcium differs among products.
  • Avoid supplements with dolomite or bone meal; they may contain lead.
  • Check your vitamin D intake, too. This vitamin is essential for absorption of calcium. Milk is a great source of vitamin D, as is sunlight.
  • If you take both calcium and iron supplements or a multivitamin with iron, take them at different times of the day. They can impair each other's absorption. This is also true of chromium, manganese, magnesium, and zinc.
  • Do not take more than 500 mg of calcium at a time. Taking the calcium with food can help absorption.

RESOURCES

Academy of Nutrition and Dietetics http://www.eatright.org/

The Nutrition Source Harvard School of Public Health http://www.hsph.harvard.edu/nutritionsource/

CANADIAN RESOURCES

Food and Nutrition Health Canada http://www.hc-sc.gc.ca/fn-an/index-eng.php

Dietitians of Canada http://www.dietitians.ca/

References

Bowes A, Pennington J, Church H. Bowes & Church Food Values of Portions Commonly Used. Philadelphia, PA: Lippincott Williams & Wilkins; 1998.

Calcium. EBSCO Natural and Alternative Treatments website. Available at: http://www.ebscohost.com/pointofcare. Updated August 2011. Accessed August 11, 2012.

Calcium. Office of Dietary Supplements website. Available at: http://ods.od.nih.gov/factsheets/calcium.asp. Accessed August 11, 2012.

Calcium intake and supplementation. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated June 25, 2012. Accessed August 11, 2012.

Dietary reference intakes for calcium and vitamin D. Institute of Medicine website. Available at: http://www.iom.edu/Reports/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D/Report-Brief.aspx?page=1. Published November 30, 2010. Accessed August 11, 2012.

Food and Nutrition Information Center. US Department of Agriculture website. Available at: http://fnic.nal.usda.gov/. Accessed August 11, 2012.

Garrison RH, Somer E. The Nutrition Desk Reference. New Canaan, CT: Keats Publishing; 1995.

Groff JL, Gropper S. Advanced Nutrition and Human Metabolism. Belmont, CA: West Publishing Company; 1995.

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