Carcinoid tumors are slow-growing tumors that affect the gastrointestinal tract and the lungs. Juicing is not especially useful for people who have carcinoid tumors, but there are certain juices that people who have carcinoid tumors need to avoid.
These tumors produce the neurotransmitter serotonin. This is the neurotransmitter that is deficient in some cases of depression. Both the brain and the digestive tract make serotonin. When there is too much serotonin production in the gastrointestinal tract, asthma and high blood pressure can become complications of the underlying carcinoid disease.
Certain plant foods contain serotonin. Black walnuts are especially high in serotonin, as are bananas, pineapples, plantains, kiwi fruit, and tomatoes. Avoid juices made from these fruits and vegetables if you have carcinoid tumors.