Calcium supplements: Which type of calcium is best?

How do I know which calcium supplement provides the most calcium? There are so many different kinds — carbonate, citrate, lactate, gluconate.

- Rose Marie / New Jersey

Answer

The key factor to consider when buying calcium supplements is the amount of elemental calcium they contain. The term "elemental calcium" refers to the amount of calcium in a supplement that's available for your body to absorb. Most calcium supplements list the amount of elemental calcium on the label. But some brands list only the total weight — in milligrams (mg) — of each tablet. This is the weight of the calcium, plus whatever it's bound to — such as carbonate, citrate, lactate or gluconate.

The simplest way to determine how much elemental calcium is in a supplement is to look at the Nutrition Facts label. For calcium, the Percent Daily Value (% DV) is based on 1,000 mg of elemental calcium, so every 10 percent in the Daily Value column represents 100 mg of elemental calcium (0.10 x 1,000 mg = 100 mg). For example, if a calcium supplement has 60 percent of the Daily Value, it contains 600 mg of elemental calcium (0.60 x 1,000 mg = 600 mg).

When choosing a calcium supplement, you should also:

• Note the serving size. This will tell you the number of tablets you must take to get the % DV listed on the label.
• Check the label for the abbreviation "USP." The best supplements meet the voluntary standards of the U.S. Pharmacopeia (USP) for quality, purity and tablet disintegration or dissolution.
• Be aware of generic brands. While generic calcium supplements are often cheaper than name brands, they may not meet voluntary standards for tablet disintegration. In other words, they may dissolve more slowly, which decreases their effectiveness.
• Avoid calcium supplements that contain unrefined oyster shell, bone meal or dolomite. These products may also contain toxic substances, such as lead, mercury and arsenic.
• Don't bother with chelated calcium tablets. They're more expensive and have no advantage over other types of calcium.

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