Some medications and conditions may inhibit calcium absorption: Protect your bones by knowing if you're taking a calcium-blocking drug, and adjust your medication schedule and calcium intake accordingly.
Corticosteroids, heartburn medications, and certain laxatives can affect calcium absorption. In addition, a certain type of diuretic used to treat hypertension, known as a "loop diuretic," also can impact calcium levels. (See chart, below, for more details on these medications.) If you are taking any of these medications, you may want to talk to your doctor about alternatives. For example, a different class of diuretic known as thiazide diuretics may reduce calcium excretion by the kidneys, which can raise blood calcium levels too high. So keeping your levels in check may require a little bit of juggling on your and your doctors part, but it is possible to manage.
The role of supplementation
The recommended daily dose of calcium is 1,000 milligrams (mg) per day for women under age 50 and men under age 70, and 1,200 mg per day for women over age 50 and men over age 70. The "tolerable upper intake level" is 2,000 mg per day for all adults over the age of 51.
If you don't get enough calcium from your diet, or if you are taking a medication or have a condition that affects calcium absorption, calcium supplements can help increase your levels, but they should be taken only in the amounts needed to bring your daily total to the recommended amount. Excess calcium from supplements may cause kidney stones, and has been linked with a higher risk of heart attacks.
According to Melissa Katz, MD, an assistant professor of clinical medicine at Weill Cornell Medical College, a typical daily calcium supplement for a postmenopausal woman with good kidney function would be 600 mg twice daily. As you get older, the efficiency of calcium absorption decreases, which is why recommended intakes are higher for women over age 50 and men over age 70. In particular, lower estrogen levels after menopause lead to decreased calcium absorption in older women.
Calcium do's and don'ts
Calcium supplements come in two forms: calcium citrate and calcium carbonate. Women who take proton pump inhibitors (PPIs) for heartburn or gastro-esophageal reflux disease are advised to take calcium citrate instead of carbonate because calcium citrate doesn't require stomach acid for absorption and can be taken with or without a meal. Calcium carbonate should be taken with a meal for effective absorption. Generally, calcium supplements can be taken at any time of day, though it's generally advised that you divide your daily recommended total into two dosages.
MEDICATIONS THAT MAY AFFECT CALCIUM ABSORPTION Loop diuretics Furosemide (Lasix), bumetanide (Bumex), torsemide (Demadex) Cortico steroids Cortisone, prednisone, prednisolone (Prelone), methylprednisolone (Medrol) Heartburn medications Esomeprazole magnesium (Nexium), omeprazole (Prilosec), lansoprazole (Prevacid), cimetidine (Tagamet), ranitidine hydrochloride (Zantac) Laxatives Ex-Lax, Correctol
If you are taking a medication that affects calcium absorption, Dr. Katz recommends not taking it at the same time as your calcium supplement. "I usually recommend that they be separated by approximately four hours," she advises.
Other factors that affect calcium levels
Certain gastrointestinal disorders can affect calcium absorption. These include celiac disease and lactose intolerance. Additionally, people who follow a vegan or ovo-vegetarian (a vegetarian diet that includes dairy) diet may require calcium supplementation.
But be aware that there also are conditions that can cause your calcium levels to be too high. "If patients with impaired kidney function take too much calcium, they can develop problems. However, paradoxically, these patients often have calcium deficiencies and need individually tailored therapy," explains Dr. Katz.
Dehydration, vomiting, diuretics, or mild kidney disease can lead to increased blood levels of calcium, which can overwhelm the kidneys to the extent that they function less effectively and may eventually result in kidney failure. However, most people are capable of excreting excess calcium as long as their kidneys are functioning properly.
Dr. Katz acknowledges that it is important not to take too much calcium, but she says it is critical to discuss supplementation with your doctor, because "calcium remains vital to bone health." Your doctor or a registered dietitian can help you determine how much calcium is right for you.