@gollum,
Absolutely! We need plenty of calcium in our diets to prevent osteoporosis. Also weight-bearing exercises are important (ie: walking rather than bike riding.) Also weight lifting helps prevent the "dowager's hump" on the upper back which is caused by osteoporosis - the bones in the upper spine become brittle and crack.
Calcium feeds bones. Natural calcium (ie: dairy products) is the best way to get it.