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Diseases & Conditions

The Role of Calcium in Preventing Osteoporosis

What is calcium?

Calcium is a mineral that the body needs for good health. Calcium is found naturally in some foods and is added to others. It also is available as a nutrition supplement and is contained in some medicines like Tums.

Why does the body need calcium?

Calcium is the healthy bone mineral. About 99 percent of the calcium in the body is stored in the bones and teeth. It is the mineral that makes them hard and strong. The remaining 1 percent is needed for many activities that help keep the body functioning normally. Calcium helps blood vessels contract and expand, makes muscles contract, helps send messages though the nervous system and helps glands secrete hormones.

Bones are constantly being remodeled every day, and calcium is moving in and out of them. In children and adolescents, the body builds new bone faster than it breaks down old bone so total bone mass increases. This continues until about age 30, when new bone formation and old bone breakdown start occurring at about the same rate. In older adults, especially in post-menopausal women, bone is broken down at a faster rate than it is built. If calcium intake is too low, this can lead to osteoporosis.

How much calcium does an adult need to take in every day?

The amount of calcium needed for healthy bones and teeth is different by age. The National Institutes of Health suggests these levels of daily intake for adults:

Daily Suggested Calcium Intake For Adults
Adults 19-50 years 1,000 mg
Adult men 51-70 years 1,000 mg
Adult women 51-70 years 1,200 mg
Adults 71 years and older 1,200 mg
Pregnant and breastfeeding teens 1,300 mg
Pregnant and breastfeeding adults 1,000 mg
Source: National Institutes of Health. Office of Dietary Supplements. ods.od.nih.gov N.d. 31 Aug. 2011

What are the recommended ways to meet this nutrition goal?

The best way to get enough calcium every day is to eat a variety of healthy foods from all the different food groups. Getting enough vitamin D every day from foods like enriched milk or from natural sunlight is important to help the body absorb and use calcium from food.

Here are some easy guidelines for selecting foods high in calcium:

  • Dairy products have the highest calcium content. Dairy products include milk, yogurt and cheese. A cup (8 oz.) of milk contains 300 mg of calcium. The calcium content is the same for skim, low fat and whole milk.
  • Dark green, leafy vegetables contain high amounts of calcium. Broccoli, kale and collards are all good sources of calcium, especially when eaten raw or lightly steamed. (Boiling vegetables takes out most of their mineral content.)
  • A serving of canned salmon or sardines has about 200 mg of calcium. It is found in the soft bones of the fish.
  • Cereal, pasta, breads and other food made with grains can add calcium to the diet. Look for cereals that are fortified with minerals, including calcium.
  • Besides cereal, calcium is added to fruit juices, soy and rice beverages and tofu. Read product labels to find out if a food item has added calcium.

At the end of this document, there is a more detailed table of calcium content in various foods. The U.S. Department of Agriculture recommends that everyone aged 9 years and older eat three servings of foods from the dairy group per day.

1 serving of dairy equals:

  • 1 cup (8 ounces) milk
  • 1 cup yogurt
  • 1.5 ounces of natural cheese (such as Cheddar)
  • 2 ounces of processed cheese (such as American)

Should I take a calcium supplement?

Calcium is best absorbed through the foods we eat and the beverages we drink. For most healthy patients, it is important to eat a well-balanced diet instead of relying on supplements alone.

For individuals who cannot get enough calcium from food and beverages each day, taking a calcium supplement may be necessary. People who have lactose intolerance might have difficulty getting enough calcium through their diet alone. In addition, those with absorption problems due to gastrointestinal illness may not absorb enough calcium. Those who follow a vegan diet, or consume large amounts of protein and sodium might also not get enough calcium.

What type of calcium supplement should I take?

The amount of calcium the body will absorb from supplements depends on the form of calcium in the supplement, how well the calcium dissolves in the intestines and the amount of calcium in the body. The two most commonly used calcium products are calcium carbonate and calcium citrate. Calcium carbonate supplements dissolve better in an acid environment so they should be taken with a meal. Calcium citrate supplements can be taken any time because they do not need acid to dissolve. For this reason, individuals who might have problems absorbing medications could consider using calcium citrate instead of calcium carbonate. This would include those who take medications to decrease stomach acid, those who have had intestinal bypass surgery, or perhaps even those 65 years and older. Calcium supplements in the form of gluconate, lactate, or phosphate are also available, but they generally contain less absorbable calcium. It is helpful to look for supplements that have the United States Pharmacopeia (USP) or consumerlab.com (CL) abbreviation on the bottle. This indicates that the products have met voluntary industry standards for quality.

The higher the calcium dose, the less it is absorbed. For the maximum absorption, no more than 500 mg of calcium should be taken in a single dose. If you need more than 500 mg as a supplement, take the doses at least 4 hours apart. If you think you need a calcium supplement, ask your doctor or a dietitian to recommend one.

What happens if I take too much calcium?

Adults ages 19 through 50 should not exceed 2,500 mg calcium total per day (including food and supplements). Adults over age 50 should not exceed 2,000 mg total per day. Dietary calcium is considered safe, but too much calcium in the form of supplements might have some health risks. These health risks include kidney stones, prostate cancer, constipation, calcium buildup in your blood vessels, and difficulty absorbing iron and zinc.

Are there any medications which interact with calcium?

Calcium can reduce the absorption of these drugs if taken at the same time:

  • Bisphosphonates (osteoporosis treatment)
  • Thyroid medication
  • Certain seizure medications (phenytoin)
  • Certain antibiotics
  • Iron supplements

What happens when the body does not get enough calcium?

Children need calcium to build strong bones. Adults need calcium to maintain strong bones. Over time, inadequate calcium intake can cause osteoporosis, the brittle bone disease. People with osteoporosis are at high risk for broken bones, especially at the wrist, hip and spine. These fractures cause chronic pain and disability, loss of independence, decreased quality of life and a higher risk of death.

Osteoporosis can cause the bones that make up the spine (the vertebrae) to break. This causes the spine to collapse in those areas, which leads to pain, difficulty in moving and gradual deformity. If the problem is severe enough, it causes a “dowager’s hump” to form, a curvature of the upper back.

Who develops osteoporosis?

Approximately 12 million Americans over age 50 have osteoporosis. Post-menopausal white and Asian women are at the highest risk for osteoporosis. According to the National Institutes for Health, half of all women over age 50 and a quarter of men older than age 50 will break a bone due to osteoporosis. About 25 percent of women with osteoporosis will develop a vertebral deformity, and 15 percent will break a hip. Osteoporosis also causes broken hips in men, although not as often as in women. More than 30 percent of people who break a hip die within a year.

Risk factors for osteoporosis include:

  • Not enough calcium in the diet
  • Age over 50
  • Small, thin body build
  • Family history of osteoporosis
  • Being a white or Asian woman
  • Smoking
  • Use of certain medications such as breast cancer treatments, seizure medications, steroids

What are the symptoms of osteoporosis?

Symptoms of bone loss do not occur until osteoporosis develops. Even then, in its early stages, osteoporosis may not cause any symptoms. Symptoms that develop as osteoporosis worsens may include:

  • Breaking bones easily
  • Back pain
  • Stooped posture
  • Gradual loss of height

How is osteoporosis diagnosed?

The outward signs of osteoporosis (height loss, easily broken bones, dowager’s hump) combined with a patient’s gender and age are strong indicators that the patient has osteoporosis. X-rays will show a broken bone, but doctors also use specialized, high-tech types of imaging that provide more information about bone health. A technology called dual X-ray absorptiometry (DXA) is the state-of-the-art technique for measuring bone mineral density (how much calcium is in the bones) and to diagnose osteoporosis.

How can osteoporosis be prevented?

Preventing osteoporosis in later years starts early – by getting enough calcium and vitamin D in childhood and adolescence to ensure that bones reach their peak strength and continuing to consume adequate calcium and vitamin D through adulthood.

To promote lifelong healthy bones and reduce calcium loss:

  • Eat a diet rich in calcium and vitamin D throughout your life
  • Enjoy regular exercise, especially weight-bearing activity like walking or jogging
  • Don’t smoke
  • Minimize caffeine and alcohol intake

The U.S. Preventive Services Task Force recommends a bone density screening by DXA in all women aged 65 years or older. They also recommended a screening test for women under the age of 65 who are at risk for fractures. This test shows the health of the bones so that preventative measures against fractures can be started if necessary.

Calcium Content of Various Foods
Food Milligrams (mg) per serving
Yogurt, plain, low fat, 8 ounces 415
Orange juice, calcium-fortified, 6 ounces 375
Yogurt, fruit, low fat, 8 ounces 338–384
Mozzarella, part skim, 1.5 ounces 333
Sardines, canned in oil, with bones, 3 ounces 325
Cheddar cheese, 1.5 ounces 307
Milk, nonfat, 8 ounces 299
Milk, reduced-fat (2% milk fat), 8 ounces 293
Milk, buttermilk, 8 ounces 282–350
Milk, whole (3.25% milk fat), 8 ounces 276
Tofu, firm, made with calcium sulfate, ½ cup 253
Salmon, pink, canned, solids with bone, 3 ounces 181
Cottage cheese, 1% milk fat, 1 cup 138
Instant breakfast drink, various flavors and brands, powder prepared with water, 8 ounces 105–250
Frozen yogurt, vanilla, soft serve, ½ cup 103
Ready-to-eat cereal, calcium-fortified, 1 cup 100–1,000
Turnip greens, fresh, boiled, ½ cup 99
Kale, fresh, cooked, 1 cup 94
Kale, raw, chopped, 1 cup 90
Tofu, soft, made with calcium sulfate, ½ cup 138
Ice cream, vanilla, ½ cup 84
Soy beverage, calcium-fortified, 8 ounces 80–500
Chinese cabbage, bok choi, raw, shredded, 1 cup 74
Bread, white, 1 slice 73
Pudding, chocolate, ready to eat, refrigerated, 4 ounces 55
Tortilla, corn, ready-to-bake/fry, one 6" diameter 46
Tortilla, flour, ready-to-bake/fry, one 6" diameter 32
Sour cream, reduced fat, cultured, 2 tablespoons 31
Sour cream, reduced fat, cultured, 2 tablespoons 31
Bread, whole-wheat, 1 slice 30
Broccoli, raw, ½ cup 21
Cheese, cream, regular, 1 tablespoon 14
Source: National Institutes of Health. Office of Dietary Supplements. ods.od.nih.gov N.d. 31 Aug. 2011
References

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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 6/26/2012…#15049