Drug stores, supermarkets and internet sites sell chelated calcium and iron pills that are advertised to be absorbed better than cheaper non-chelated minerals. Are they worth the price?

You can get all the minerals that you need from the food that you eat. But if you want to take extra minerals, chelated minerals offers no advantage over non-chelated ones. In your intestines, minerals are bound to components of almost everything that you eat, such as organic acids like citric acid in fruits, sugars like those found in milk, and amino acids like these found in any protein source that you eat.

Mineral absorption depends on what is in your stomach and intestines when you eat the mineral. For example, fat increases and fiber decreases mineral absorption. Vitamin C will significantly increase the absorption of iron from plant foods. One mineral can affect the absorption of another. Taking large amounts of zinc markedly inhibits copper absorption. Taking calcium with iron together reduces absorption of both minerals. If you're not confident that you are getting enough calcium in your diet, you can use fortified foods like calcium-added orange juice, soy milk or breakfast cereals, or you can take generic calcium carbonate pills. Expensive "coral calcium" supplements are nothing but ordinary limestone which offers no advantage over generic calcium carbonate. Chelation or lack of chelation is insignificant compared to the variable conditions in your digestive system.