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Calcium

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How does Calcium work?

The bones and teeth contain over 99% of the calcium in the human body. Calcium is also found in the blood, muscles, and other tissue. Calcium in the bones can be used as a reserve that can be released into the body as needed. The concentration of calcium in the body tends to decline as we age because it is released from the body through sweat, skin cells, and waste. In addition, as women age, absorption of calcium tends to decline due to reduced estrogen levels. Calcium absorption can vary depending on race, gender, and age.

Bones are always breaking down and rebuilding, and calcium is needed for this process. Taking extra calcium helps the bones rebuild properly and stay strong.

Are there safety concerns?

Calcium is LIKELY SAFE for most people when taken by mouth or when given intravenously (by IV) and appropriately. Calcium can cause some minor side effects such as belching or gas.

Calcium is POSSIBLY UNSAFE for both adults and children when taken by mouth in high doses. Avoid taking too much calcium. The Institute of Medicine sets the daily tolerable upper intake level (UL) for calcium based on age as follows: Age 0-6 months, 1000 mg; 6-12 months, 1500 mg; 1-8 years, 2500 mg; 9-18 years, 3000 mg; 19-50 years, 2500 mg; 51+ years, 2000 mg. Higher doses increase the chance of having serious side effects, such as blood levels of calcium that are too high and milk-alkali syndrome, a condition that can lead to renal stones, kidney failure and death. There is also concern that supplemental calcium can increase the risk of heart attack. Some research shows that taking calcium, often in amounts over the recommended daily intake level of 1000-1300 mg per day, is linked with an increased risk of heart attack in older people. But other research suggests there is no connection between calcium supplementation and heart attack risk. It may be that some groups have an increased risk while others do not. Continue consuming adequate amounts of calcium to meet daily requirements, but avoid excessive amounts of calcium. Be sure to consider total calcium intake from both dietary and supplemental sources and try not to exceed 1000-1200 mg of calcium per day. To figure out dietary calcium, count 300 mg/day from non-dairy foods plus 300 mg/cup of milk or fortified orange juice. Also, if calcium supplements need to be taken along with dietary calcium, consider taking ones that provide calcium along with vitamin D.

Special Precautions & Warnings:

Pregnancy and breast-feeding: Calcium is LIKELY SAFE when taken by mouth in recommended amounts during pregnancy and breast-feeding. There is not enough information available on the safety of using calcium intravenously (by IV) during pregnancy and breastfeeding.

Low acid levels in the stomach (achlorhydria). People with low levels of gastric acid absorb less calcium if calcium is taken on an empty stomach. However, low acid levels in the stomach do not appear to reduce calcium absorption if calcium is taken with food. Advise people with achlorhydria to take calcium supplements with meals.

High levels of phosphate in the blood (hyperphosphatemia) or low levels of phosphate in the blood (hypophosphatemia): Calcium and phosphate have to be in balance in the body. Taking too much calcium can throw this balance off and cause harm. Don't take extra calcium without your health provider's supervision.

Under-active thyroid (hypothyroidism): Calcium can interfere with thyroid hormone replacement treatment. Separate calcium and thyroid medications by at least 4 hours.

Too much calcium in the blood (as in parathyroid gland disorders and sarcoidosis): Calcium should be avoided if you have one of these conditions.

Poor kidney function: Calcium supplementation can increase the risk of having too much calcium in the blood in people with poor kidney function.

Smoking: People who smoke absorb less calcium from the stomach.

Stroke: Early research suggests that older women who have had a stroke, taking calcium supplements for 5 or more years might increase the chance of developing dementia. More research is needed to determine if calcium supplements should be avoided for those who have had a stroke.


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