Why supplement with calcium continued.

We are probably all aware to some extent, that the quality of our food is not what it used to be,
because of modern farming practice, (chemical fertilizers etc). We may not be so aware that
greenhouse gases and selective breeding have also contributed to nutrient loss. Then you add to that the losses through processing and transport, and you begin to wonder that we still have as much health as we do. Not that the situation is all that good, with a 2002 study showing that practically nobody is receiving the recommended intake of vitamins and minerals.
What We Eat In America, N HANES, 2001, 2002.

At the Illinois long term Corn Experiment (testing for over 100 years), it was found that protein in corn has decreased about .3% every decade of the 20th century. You can only wonder about the other nutrients.

Then what about this one?
"Most commercial fruit including tomatoes is picked green and ripened artificially. Produce picked early does not develop sun related anthocyanens and polyphenols, compounds that give fruit their colors and flavours and which protect humans against DNA damage, brain cell deterioration and cancer."
Journal of Agriculture and Food Chemistry, 6 April, 2005, 53.

Coral calcium is one way of helping restore some minerals to the food chain. But it may be worth considering other ways where a more complete range of nutrients is involved. Generally supplementation works better that way.