Micronutrient deficiencies in patients with gastrointestinal cancer: To treat or not to treat.

Nutrition supplements are widely used among patients with cancer. The general public perceives supplements as more natural anticancer and antitoxicity agents, and often supplements are used without the knowledge of the treating physician. In the clinical setting, there are concerns that supplements may decrease effectiveness of chemotherapy and/or radiotherapy and, as a result, supplementation is avoided. There is a body of literature evaluating micronutrient deficiencies, supplementation, and cancer risk; however, little is known about the risks of treatment of micronutrient deficiencies in specific cancers. Of the types of cancers, patients with gastrointestinal cancers are at high risk of developing malnutrition and, subsequently, possible micronutrient deficiencies. This review aims to evaluate the effects of supplementation of specific micronutrients in patients with cancer of the digestive tract.