I have tried to learn as much as possible about the Hart Dietary Procedure Plan. As I understand it UNBALANCED calcium is to be avoided. This is calcium that is not bound to other substances such as magnesium which allows it to bind with oxalic acid within the intestines....thereby forming stones. Cow milk and tap water have excess calcium in proportion to the magnesium, potassium, etc. Sources of calcium such as squash, almonds, salmon, etc. are balanced with magnesium and not free to attach to the oxalic acid. Therefore, those foods rich in calcium are not able to bind with oxalic acid and form stones. To my knowledge no one on this diet has developed kidney stones. I believe it is because they do not ingest foods disproportionate in calcium content. I do know that three patents have been granted. One for the use of oxalic acid to treat cancer, a second for the use of oxalic acid to treat viral and bacterial disease, and a third for the use of oxalic acid to treat vascular disease, disorders and other calcerous conditions. This is a first where patents have been granted for a natural substance. If you are really interested, I can give you the patent numbers and dates for further research.