Although calcium plays an important role in bone growth and formation, excessive amounts can cause serious health problems. To avoid negative side effects of excessive calcium intake, obtain most of your calcium from food sources, which are less likely to cause overdose symptoms, and discuss calcium supplements with your doctor before regular use.
Vitamin Absorption
Excessive calcium intake can interfere with the absorption of other vitamins and minerals. For example, according to the National Institutes of Health Office of Dietary Supplements, too much calcium may decrease the body's ability to absorb zinc and iron. In fact, people with iron-deficiency anemia should avoid consuming calcium-rich foods or taking calcium supplements with their meals, because calcium interferes with the absorption of iron both from food sources and from iron supplements. If you have children who drink more than 24 oz. of milk each day, you should also ensure that their iron intake is adequate, because iron-deficiency anemia is common at younger ages.
Kidney Problems
Persons who have a chronic kidney disease may need to decrease their daily calcium intake. According to a 2005 article by clinical consultant Micki Misiaszek of Genzyme Corp., high calcium intake combined with excessive amounts of phosphorus can cause calcifications in the heart, blood vessels, lungs and joints. Symptoms of calcification include heart failure, circulation problems, pain in the joints and shortness of breath. In patients who are on dialysis, high calcium intake has even been linked to higher risk of death. For these reasons, doctors recommend that kidney disease patients limit their total calcium intake to 2,000 mg.
Hypercalcemia
The American Academy of Family Physicians notes that hypercalcemia, or high calcium levels in the blood, is actually a common condition encountered by primary care physicians, although it is often undiagnosed. This condition causes a variety of symptoms, including nausea, stomach pain, constipation, anorexia and pancreatitis. Hypercalcemia is often related to overactive thyroid gland activity, or hyperparathyroidism, as well as cancer, medications and dehydration. However, it can also be caused by excessive intake of calcium or vitamin D for an extended period of time.
Recommendations
To avoid negative health effects from excessive calcium intake, aim to consume about 1,000 mg per day, which is the recommended daily intake for most healthy adults. The Food and Nutrition Board has also set a tolerable upper limit for calcium of 2,500 mg for adults ages 19 to 50 and or 2,000 mg for those over 50. The tolerable upper limit indicates how much calcium most normal adults can consume without experiencing negative side effects. Overdose is much less likely to occur from food sources, so obtain as much as you can from your diet before you consider using a supplement.
References
- National Institutes of Health Office of Dietary Supplements; Calcium; June 2011
- Medline Plus; Iron; June 2011
- Centers for Disease Control and Prevention ;Iron and Iron Deficiency; February 2011
- "Kidney Beginnings: The Magazine"; Are You Getting Too Much Calcium?; Micki Misiaszek; December 2005
- American Family Physician; A Practical Approach to Hypercalcemia; Mary F. Carroll and David S. Schade; May 2003
- MayoClinic.com; Hypercalcemia; May 2011
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