In 'Wheat Belly' by Dr. William Davis,
He says that taking extra calcium is useless and that we build bone until we are about 18, then we spend the rest of our lives tearing it down, a process regulated by body PH. The chronic mild metabolic acidosis engineered by our diet worsens as we age, starting in our teens and worsening through the eighth decade." and says, "incidentally, taking calcium supplements is no more effective at reversing bone loss than randomly tossing some bags of cement and bricks into your yard is at building a new patio."

"The acidic PH pulls calcium carbonate and calcium phosphate from bone to maintain the body PH of 7.4. The acidic environment also stimulates bone resorbing cells within bone, known as osteoclasts, to work harder and faster to dissolve bone tissue to release the precious calcium."
"The problem comes when you habitually ingest acids in the diet, then draw on calcium stores over and over and over again to neutralize those acids.
An excessively acidified diet will eventually show itself as bone fractures." because the body in an effort to keep "the body slightly alkaline will sacrifice bone health to keep the body pH stable. If not eating Wheat, "Meats such as chicken, pork and beef are a major source of acid in the average American diet.
Acids yielded by meat include uric acid and sulfuric acid (the same as your car battery and acid rain). However protein rich foods may not be as harmful to pH balance as it first appears. Recent research suggests that protein-rich meats have other effects that particularly negate the acid load. Animal protein exerts bone strengthening effect through stimulation of the hormone insulin growth factor (IGF-1) which triggers bone growth and mineralization."

"Vegetables and fruits, on the other hand, are the dominant alkaline foods in the diet. Virtually everything in your produce department will drive pH toward the alkaline direction. From kale to kohlrabi, generous consumption of vegetables and fruits serve to neutralize the acidic burden from animal products."