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 (narrow) and expand, makes muscles contract, helps send messages through 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 contribute 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: Calcium Dietary Supplement Fact Sheet - National Institutes of Health. Office of Dietary Supplements.|
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 (such as over-the-counter and prescription heartburn medications). Also, those who have had intestinal bypass surgery, or perhaps even those 65 years and older, may benefit from calcium citrate instead of calcium carbonate.
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 get more than 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, increased risk of prostate cancer, constipation, calcium buildup in your blood vessels, and difficulty absorbing iron and zinc.
Are there any medications that 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 (long-lasting) 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 these 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 of 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
- 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 signs that the patient has osteoporosis. 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?
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
- Go easy on the caffeine and alcohol.
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|
- National Institutes of Health. Calcium Dietary Supplement Fact Sheet Accessed 10/23/2015.
- National Institutes of Health. Calcium Fact Sheet for Consumers Accessed 10/23/2015.
- National Osteoporosis Foundation. Calcium and Vitamin D: What You Need to Know Accessed 10/23/2015.
- Summaries for patients: Screening for osteoporosis: recommendations from the U.S. preventive services task force. Ann Intern Med. 2011 Mar 1;154(5):I40.
- Agency for Healthcare Research and Quality (US). Multivitamin/Mineral Supplements and Prevention of Chronic Disease. Evidence Reports/Technology Assessments, No. 139. Rockville, Md., 2006.
© Copyright 1995-2015 The Cleveland Clinic Foundation. All rights reserved.
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: 10/23/2015…#15049