Calcium Requirements and Dietary Sources

Dairy products are high in calcium.
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Dietary calcium is a major mineral, and it's the most abundant mineral in the human body. Most calcium is stored in the bones, and teeth (about 99 percent) and the rest is in your blood, muscles, and extracellular fluid.

Calcium is necessary for healthy bones and teeth. Your body constantly breaks down and rebuilds your bones to keep them strong. When you're young, your body builds up calcium as fast as it removed it from the bones, but when you get older, your body tends to reabsorb more calcium than it puts back, so you're at a greater risk for weak and brittle bones.

Calcium also plays a significant role in blood clotting, muscle contraction, hormonal secretion and normal nervous system function.

The National Academies of Sciences, Engineering and Medicine, Health and Medicine Division has determined the dietary reference intakes (DRI) for calcium. It's based on the daily nutritional needs of an average healthy person and differs by age and sex. If you have any medical issues, you should speak with your health care provider about your calcium requirements.

Dietary Reference Intakes

Ages 1 - 3: 700 milligrams per day
Ages 4-8: 1,000 milligrams per day
Ages 9-18: 1,300 milligrams per day
Men ages 19-70: 1,000 milligrams per day
Women ages 19-50: 1,000 milligrams per day
Women ages 51 and older: 1,200 milligrams per day
Men ages 71 and older: 1,200 milligrams per day

Calcium Deficiency Signs and Symptoms

Long-term calcium deficiency can lead to osteopenia, which is a loss of bone density.

Osteopenia may progress into osteoporosis, a health condition where bones become weak and brittle. Most adults need from 1,000 to 1,200 milligrams of calcium every day. That need can be met when you eat a balanced diet that includes dairy products, bony fish, dark green vegetables, and calcium-fortified foods.

You probably won't feel any actual symptoms of calcium deficiency, unless you have hypocalcemia (low blood calcium), which is usually due to health conditions or certain medications and treatments. The symptoms of hypocalcemia include muscle cramps, lethargy, numbness and tingling in the fingers, and problems with heart rhythm. These can all be signs of other health conditions too, so if you have them, you need to see your health care provider.

Calcium deficiency can occur when you don't eat enough foods that contain calcium or if you eat too much protein and sodium-rich foods, which cause your body to excrete calcium. If you're low in vitamin D, Your body needs vitamin D to absorb and use calcium -- that's why milk is fortified with vitamin D. However, most of your vitamin D is formed in your body when your skin is exposed to sunlight. The Institute of Medicine suggests a daily intake of 600 to 800 International Units of vitamin D per day.

Taking Calcium Supplements

Calcium supplements are often recommended for adult females to help prevent osteoporosis.

They're generally safe. However, the Institute of Medicine has determined the tolerable upper limit to be 2,500 milligrams per day. Taking more than that amount on a regular basis may lead to hypercalcemia, kidney problems, and may impair the absorption of other minerals.

It's also important to know that calcium supplements can interact with several medications, so consult your doctor before taking calcium -- or any supplements -- if you're also taking any prescription drugs. 

Sources:

National Academies of Sciences, Engineering and Medicine, Health and Medicine Division. "Dietary Reference Intakes Tables and Application." Accessed March 25, 2016. http://www.nationalacademies.org/hmd/Activities/Nutrition/SummaryDRIs/DRI-Tables.aspx.

National Institutes of Health. Office of Dietary Supplements. "Dietary Supplement Fact Sheet: Calcium." Accessed March 25, 2016. http://ods.od.nih.gov/factsheets/calcium/.

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