Calcium Patient Information Fact Sheet

What is calcium?
Calcium is the main component of bone. It makes up about 67% of human bone tissue with the remaining 33% being comprised of collagen fibers. Collagen gives the bone flexibility while calcium gives it strength and rigidity. Ninety-nine percent of calcium in the body is found in the bones and teeth.

Calcium is deposited by specialized bone cells that are controlled by a hormone from the thyroid gland. It is estimated that the whole skeleton is replaced every 7 to 10 years in adults and every 2 years in children, so a regular intake of calcium is required. Other cells in the body such as the heart, nerves and muscles also require calcium to function normally. If blood levels of calcium become low, the body will take calcium from the bones, which may result in weakened bones if this calcium is not replaced. Calcium deposits and bone density can be laid down in bones until about the age of 30. Whether or not you develop osteoporosis later in life can be dependent on the level of bone mass acquired during these early years.

When is it necessary to take extra calcium?
Calcium supplements are necessary in a number of situations. For example, people with hypothyroidism, a condition in which the thyroid gland does not work effectively, may require calcium supplements. Children who suffer from milk allergies or multiple food allergies may also require additional calcium as they may not receive adequate amounts from their diet. Some strict vegetarians may also lack calcium as a result of dietary insufficiencies. Calcium requirements are greatest during growth periods, including pregnancy and lactation.

Lowered progesterone levels, such as occurs following menopause, can cause bone loss if dietary intake of calcium is low. Post-menopausal women are also often given calcium supplements. Osteoporosis is a condition in which the bones lose calcium and become porous and brittle as a result. This leads to an increased incidence of fractures, particularly in post-menopausal women. It is very important to ensure that sufficient calcium is taken before osteoporosis or bone weakness occurs; prevention is a continual process and should be a lifelong consideration.

How much supplemental calcium is needed?
Ask your doctor about the amount of calcium it is necessary for you, as an individual, to take. Calcium is available as a number of different salts including carbonates (Os-Cal), gluconates, lactates and phosphates. Calcium supplements are available in a number of different formulations, including chewable tablets and “candies,” effervescent tablets, powders, and liquids. They are usually taken once a day. Calcium and vitamin D supplements have been  proven to reduce the risk of hip fracture in older people. The only side effect of calcium supplements may be gastric irritation, so people with ulcers or other gastric problems may need careful observation.

Self-help measures

  • Ensure you eat a balanced diet that includes enough calcium-containing foods (see recommended daily intakes above). Avoid eating excessive amounts of protein or salt as this can result in loss of calcium. Your salt intake should not exceed 6g per day.
  • Do regular weight-bearing exercise (eg, jogging, walking, dancing). Exercise strengthens the bones and helps the body to store calcium.
  • Increase calcium intake at particular times of life when calcium needs are greater, such as during pregnancy and breast feeding and after menopause.  Women should ensure that they increase their calcium intake at these times so that calcium is not taken from their bones causing bone weakness.
  • Avoid smoking, excess caffeine and excess alcohol - these can all interfere with calcium levels, particularly if the dietary calcium intake is low.
  • Maintain a healthy body weight - being overweight is bad for your health in general while being underweight can increase the risk of broken bones if you fall.

Recommended Daily Calcium Intakes

Children 1–3 years

700mg

Children 4–8 years

1,000mg

Boys 9–18 years

1,300mg

Girls 9–18 years

1,300mg

Adults (men and women,including pregnant women*)

1,000mg–1,200mg

*women who are breastfeeding may require additional calcium


Selected Food Sources of Calcium

Food

Milligrams (mg)

per serving

Percent DV*

Yogurt, plain, low fat, 8 ounces

415

42

Orange juice, calcium-fortified, 6 ounces

261

26

Yogurt, fruit, low fat, 8 ounces

313–384

31–38

Mozzarella, part skim, 1.5 ounces

333

33

Sardines, canned in oil, with bones, 3 ounces

325

33

Cheddar cheese, 1.5 ounces

307

31

Milk, nonfat, 8 ounces**

299

30

Milk, reduced-fat (2% milk fat), 8 ounces

293

29

Milk, buttermilk, lowfat, 8 ounces

284

28

Milk, whole (3.25% milk fat), 8 ounces

276

28

Tofu, firm, made with calcium sulfate, ½ cup***

253

25

Salmon, pink, canned, solids with bone, 3 ounces

181

18

Cottage cheese, 1% milk fat, 1 cup

138

14

Tofu, soft, made with calcium sulfate, ½ cup***

138

14

Instant breakfast drink, various flavors and brands,

powder prepared with water, 8 ounces

105–250

10–25

Frozen yogurt, vanilla, soft serve, ½ cup

103

10

Ready-to-eat cereal, calcium-fortified, 1 cup

100–1,000

10–100

Turnip greens, fresh, boiled, ½ cup

99

10

Kale, fresh, cooked, 1 cup

94

9

Kale, raw, chopped, 1 cup

100

10

Ice cream, vanilla, ½ cup

84

8

Soy beverage, calcium-fortified, 8 ounces

80–500

8–50

Chinese cabbage, bok choi, raw, shredded, 1 cup

74

7

Bread, white, 1 slice

73

7

Pudding, chocolate, ready to eat, refrigerated, 4 ounces

55

6

Tortilla, corn, ready-to-bake/fry, one 6” diameter

46

5

Tortilla, flour, ready-to-bake/fry, one 6” diameter

32

3

Sour cream, reduced fat, cultured, 2 tablespoons

31

3

Bread, whole-wheat, 1 slice

30

3

Broccoli, raw, ½ cup

21

2

Cheese, cream, regular, 1 tablespoon

14

1

Source: National Institutes of Health, Office of Dietary Supplements

* DV = Daily Value.

** Calcium content varies slightly by fat content; the more fat, the less calcium the food contains.

** Calcium content is for tofu processed with a calcium salt. Tofu processed with other salts does not provide significant

amounts of calcium.


Further information
NIH Osteoporosis and Related Bone Diseases National Resource Center: www.niams.nih.gov/Health_Info/Bone/Osteoporosis
Office of Dietary Supplements: http://ods.od.nih.gov/factsheets/Calcium-HealthProfessional/

Last Reviewed: June 2013

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