The gluconate salt of calcium. An element or mineral necessary for normal nerve, muscle, and cardiac function, calcium as the gluconate salt helps to maintain calcium balance and prevent bone loss when taken orally. This agent may also be chemopreventive for colon and other cancers. OR A form of the mineral calcium that is used to prevent or treat osteoporosis (a decrease in bone mass and density) and to treat heartburn and upset stomach. It is also being studied in the prevention of bone problems in people with cancer. It is a type of dietary supplement.