Another list has carried the following information: "A Dutch study published in the November, 2002 issue of Brain, Behavior and Immunity (the official journal of the PsychoNeuroImmunology Research Society), found that tryptophan worked directly on the brain to alter cognitive functioning and produce mood swings and depression in human subjects. ... turkey protein contains an excess of this amino acid." So do certain cheeses, such as parmesan and mozzarella, according to the same post. Anyone in a position to comment on this Dutch study? Evelyn