Calcium is present in a wide range of foods. Dairy products, leafy green vegetables, nuts and seeds (almonds, brazils, sesame seeds), tofu, and dried fruit are all good sources of calcium for vegetarians. 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. Saturated fats can also lessen calcium absorption.
Calcium is lost in the faeces, urine and sweat. Calcium loss is roughly equal to dietary calcium in adults. Calcium loss is reduced if dietary calcium is low. Adaptation to both high and low calcium intakes occur. Reduced intake leads to increased efficiency of absorption. In infants and children calcium is retained for new bone growth. Calcium is also lost during lactation in breast milk.
Foods rich in calcium are :
• Ragi, a millet, is a rich source of calcium and known as poor man’s milk.
• Green leafy vegetables are very rich sources of Vitamin B, carotene, iron, calcium, Vitamin B complex and Vitamin C .
• Milk is a good source of protein, calcium and vitamins.
• Yogurt (Curds), paneer, fenugreek leaves, drumstick leaves, Almond, Dried Figs (Anjeer) are great source of protein, riboflavin and calcium.
• Pineapple is tropical fruit. It is a good source of Vitamin A and B and rich in Vitamin C and calcium. It also contains phosphorus and iron.
• Sea Food: Small fish like sprats and sardines can be a useful source of calcium when eaten whole together with bones and may supply up to 400 mg of calcium/ 100 gms. Fish also contains fair amount of copper.