Dq is correct. Let's take it a step further with specifics.
The bottom line cause of disease: When there's a blockage/impairment of healthy blood flow to any tissue, then you'll have a disease process. "Life is in the blood." And, unfortunately, disease is the lack of the life process which is in the blood.
Some of the blockages of healthy blood flow are . . . catarrh, calcium carbonate and calcium cholesterol stones, etc.