Excess calcium in the blood can cause nausea, vomiting and calcium deposition in the heart and kidneys. This usually results from excessive doses of vitamin D and can be fatal in infants . Dietary Sources Calcium is present in a wide range of foods. Most flour is fortified with calcium carbonate so cereals can also be a good source. Hard water may also provide calcium.
Meat is a very poor source of calcium.
Calcium balance can be affected by a range of other factors. Vitamin D is essential for absorption of calcium from the gut. This is because calcium is transported into the body by a special carrier protein which requires vitamin D for its synthesis. A number of substances can inhibit the absorption of calcium. Phytic acid, found in bran, whole cereals and raw vegetables is one of these.