Calcium is vital for a wide range of bodily functions, such as bone development, brain function and muscle activity. Too much calcium intake can cause hypercalcemia, a condition in which blood calcium levels rise too high. While most of the calcium in the body is sequestered in the bones, the body maintains a steady supply in the bloodstream as well. Most people need between 1,000 and 1,300 mg of calcium every day.
Hypercalcemia
If the calcium overdose is not too high, mild symptoms may occur. These can include nausea, constipation, loss of appetite, abdominal pain, vomiting, dry mouth and frequent urination. Severe hypercalcemia may occur if high doses of calcium are taken over a long period of time. In severe hypercalcemia, neurological symptoms may appear. They may include confusion, emotional disturbances, hallucinations, delirium and coma. In some cases, the affected individual may die
Causes
Hypercalcemia does not occur as a result of eating too much calcium, since the calcium levels in food are too low to cause this problem, according to the Linus Pauling Institute. Instead, cases of abnormally high calcium ingestion are usually the result of taking supplements. Most multivitamins do not contain enough calcium to be of concern, but taking multiple high-dose calcium supplements along with antacids containing calcium may lead to health problems.
Interactions
High doses of calcium can interfere with the absorption of iron from sources other than meat, such as from iron supplements and plant sources. Other nutrients that may be affected by calcium intake include magnesium, phosphorus and zinc. Too much calcium can also interfere with some drugs, including some antibiotics, anticonvulsants and medications for osteoporosis.
Amounts
Calcium supplementation at levels of 1.5 to 16.5 g per day for a duration of two days to 30 years have been found to induce hypercalcemia. The tolerable upper level of calcium intake, set by the the Food and Nutrition Board of the Institute of Medicine, is 2,500 mg, or 2.5 g, per day.
Potential Effects
An epidemiological study of 50,000 men in the journal "Cancer Research" found that an intake of 2,000 mg of calcium or more each day increased the risk of prostate cancer when compared with an intake of 500 mg per day. In some individuals, high levels of supplemental calcium may also contribute to the development of kidney stones, but for most people, reasonable levels of intake appear to be linked to a lower risk of kidney stones.
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