Calcium is available in many forms. Lead has been found in some types, so use caution when choosing a product. Lead is a toxic metal that can harm the brain and kidneys, and can reduce red blood cell production. Children are most at risk for lead poisoning. The following are some of the available forms of calcium:

• Calcium citrate. This is the most easily used form of calcium, but does contain some levels of lead.
• Calcium carbonate. This type is less expensive, and lead levels are safe if it is refined. Rolaids® and Tums® contain calcium carbonate. Other antacids contain aluminum and can harm your calcium balance.
• Calcium gluconate. This type is safe. Derived from vegetable sources.
• Calcium chloride. This is not recommended because it irritates the gastrointestinal tract.

You should be cautious with products that may contain harmful levels of lead. These include unrefined calcium carbonate from oyster shells or limestone, bone meal, and Dolomite.