Everyone needs calcium for a healthy body, bones and teeth. We absorb most of our calcium through a good diet and natural sunlight. But as we age, we lose bone density and strength, which can lead to osteoporosis (brittle bone disease). Here are the numbers on how much calcium you need, and the best ways to get it.
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®.
Calcium is the healthy bone mineral. About 99% of the calcium in the body is stored in the bones and teeth. It's the mineral that makes them hard and strong. The remaining 1% 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 moves 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's built. If calcium intake is too low, this can contribute to osteoporosis.
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
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:
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:
Calcium is best absorbed through the foods we eat and the beverages we drink. For most healthy patients, it's important to eat a well-balanced diet instead of relying on supplements alone.
For those who can't 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.
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, people 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's 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's 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 four hours apart. If you think you need a calcium supplement, ask your doctor or a dietitian to recommend one.
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. Too much calcium has the potential to increase the risk of kidney stones, constipation or even calcium buildup in your blood vessels, along with difficulty absorbing iron and zinc.
Calcium can reduce the absorption of these drugs if taken at the same time:
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.
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. Post-menopausal white and Asian women are at the highest risk for osteoporosis. About 25% of women with osteoporosis will develop a vertebral deformity, and 15% will break a hip. Osteoporosis also causes broken hips in men, although not as often as in women. Hip fractures are associated with an increased risk of death within the year after the bone break.
Risk factors for osteoporosis include:
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:
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.
To promote lifelong healthy bones and reduce calcium loss:
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 strength of the bones so that preventative measures against fractures can be started if necessary.
Calcium content of various foods
Last reviewed by a Cleveland Clinic medical professional on 11/29/2020.
Learn more about our editorial process.