I don't think the LRA would show starch per say because it is not a direct stimulant for the immune system. Dr. Alan Ebringer theorized that Klebsiella pnemonia fed on starch and that KP's lipid shells would get into the blood stream causing an anti-body response.
I think what is going on here with the LRA is it identifies which substance stimulate an anti-body response. It shows which substances activated lymphocytes which includes B Cells. B Cells of course produce antibodies so that could trigger a flareup by dumping KP antibodies into the blood stream where they would then cause damage.
That is my novice rational for the disease model any way and should not be viewed as anything more than a poor schlub's attempt to make sense of the disease with limited hard evidence to work with.