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. Uronic acid, a component of dietary fibre, and oxalic acid, found in certain fruits and vegetables can also bind calcium. However, diets habitually high in these acids are not thought to have a major effect on calcium absorption.