Taken out of A Chiropracters website
"Chiropractic care affects the nerves that are surrounded by your vertebrae. These nerves lead to vital organs, cells and glands that make your entire body, its structure and immune system operate properly on a daily basis.
When your immune system suffers an interference, it can become vulnerable and you may experience pain or get sick. Pain is a sign of tissue destruction. Other problems may actually exist before any pain begins.
When a chiropractor adjusts or realigns misplaced vertebrae (subluxation), he restores the proper nerve and blood flow to your body naturally"