Health Questions and Answers

Question: Why is cancer referred to as a “nitrogen sink”?


Protein is the major source of nitrogen in the human body. Tumors derive protein at the expense of the host. Tumors act as “nitrogen sinks” by depleting the patient’s protein mass and altering protein metabolism. Whole body turnover of protein is increased. Both hepatic synthesis of protein and protein catabolism are increased. Muscle protein synthesis is decreased and muscle protein breakdown increased. In simple starvation, by contrast, hepatic synthesis rates are decreased. The cancer patient shows a lack of the normal metabolic responses which conserve protein during both starvation and stress.

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