Food/Drug Interactions
False-positive urine test for carcinoid syndrome. Carcinoid tumors, which may arise from the
tissues of the endocrine or gastrointestinal systems, secrete serotonin, a nitrogen compound
that makes blood vessels expand or contract. The test for these tumors measures the amount
of serotonin in the blood. Eating walnuts, which are high in serotonin, in the 72 hours
before taking the test for a carcinoid tumor may cause a false-positive result, suggesting that
you have the tumor when in fact you do not. (Other foods high in serotonin are avocados,
bananas, eggplant, plums, pineapple, and tomatoes.)
Nuts