I don't know about de Coti-Marsh's system but I know that when I cut out certain foods, e.g. corn and the deadly nightshade family, i.e. potatoes and tomatoes, my aches disappear.
Arthritis Research Uk is a good place to start. The nightshade family is week researched as a trigger for arthritis pain. Whether cutting it out actually does anything about the underlying cause is up for debate I believe.