9 pointers for choosing a calcium supplement

Calcium is an important mineral and many people don't get enough from their diet or multivitamin alone. Follow these 9 guidelines when taking a calcium supplement to keep your bones and body healthy.

• This is the amount that's available for absorption in your gastrointestinal system. The less elemental calcium per pill, the more pills you'll need to reach your goal.
• Check the Daily Value column on the nutrition facts label.

• Both types work equally well.
• If you eat most meals at home and you're already in the habit of taking supplements or other pills regularly, choose carbonate. It's the least expensive, provides the most elemental calcium per pill, and is best absorbed about an hour or so after a meal.
• If you're busy, eat out often, or are forgetful, choose calcium citrate. It's a little pricier, but it's better absorbed on an empty stomach.
• What about other types of calcium? You could choose calcium gluconate, calcium lactate, or calcium phosphate, but they only contain about 9 percent elemental calcium.
• Avoid brands made with bonemeal, dolomite, or oyster shells because they may contain lead or other heavy metals.

Take this amount for one week and see how you feel. Some types may cause gas and constipation, so switch to a different type if you experience these symptoms.

Your body can't absorb more than that. If you take two 500-milligram calcium supplements a day, space them at least three hours apart for optimal absorption.

• If you have a glass of milk and a slice of cheese with lunch, you've just gotten at least 500 milligrams of high-quality calcium and don't need a supplement right now. If you have just a smidge of calcium at dinnertime and you haven't had much other calcium during the day, adding a supplement could bring you up to your daily goal of 1,200 milligrams.
• 250 milligrams (1 cup) of fat-free milk plus a 250 grams (1 cup) of fortified breakfast cereal could provide nearly a day's worth of calcium. If your morning calcium quota's being met, don't bother adding a supplement: save it for later so you'll get the most benefit.
• Try to use supplemental calcium to add calcium to meals that don't contain it naturally.

• Calcium won't do your bones any good if the supplement doesn't break down in your digestive system so your body can absorb it.
• Look for name brands, types labeled "purified," and those with the United States Pharmacopeia (USP) symbol.
• Alternatively, go with a chewable or liquid supplement.

Wondering about your pill's absorbability? Place one in a small glass of warm water for a half hour and stir occasionally. If it hasn't dissolved in 30 minutes, it probably won't break down in your stomach either.

Keep a bottle at your desk, in the kitchen, and in your car. Why? Calcium only protects bones when you take it faithfully — every single day.

• Calcium can interfere with the absorption of antibiotics like tetracycline, thyroid hormones, corticosteroids, and even iron supplements.

When taking supplemental calcium, keep in mind the type, timing, and amount. And don't forget the most important thing: consistency! Follow these guidelines and you'll be helping your bones stay strong.