0 The New Complete Book of Food
Medical Uses and/or Benefits
* * *Adverse Effects Associated with This Food
* * *Food/Drug Interactions
False-positive test for carcinoid tumors. Carcinoid tumors, tumors that may arise from tissues
of the endocrine or gastrointestinal systems, secrete serotonin, a chemical that makes blood
vessels expand or contract. Because serotonin is excreted in urine, these tumors are diag-
nosed by measuring the serotonin levels in the patient’s urine. Plums contain large amounts
of serotonin. Eating plums in the 72 hours before the test might give a false-positive result,
suggesting that you have an endocrine tumor when in fact you do not. (Other foods rich in
serotonin include avocados, bananas, eggplant, pineapple, tomatoes, and walnuts.)