Dan maybe you can elaborate on this because I'm bad at that part. But isn't it true that we cant absorb the type of calcium found in calcium chews or fortified foods such as milk and orange juice. Also that osteoporosis isn't prevalent throughout the world, the countries that consume the most milk and dairy are the ones with the highest rates of osteoporosis.
Ive even heard that milk is an "anti-calcium" it inhibits calcium absorptiion.
The best way to get calcium is with a well balanced diet, there are lots of foods with enough calcium in them, many vegetables, nuts and fish.