Zinc: A complementary factor in the treatment of chronic hepatitis C? (Review)

Chronic hepatitis C (HCV) infection persists in more than 170 million people worldwide and is one of the major causes of hepatic failure and liver transplantation. Current treatment of chronic HCV, consisting of pegylated interferon and ribavirin, is associated with a wide range of side effects, contraindications and costs, and leads to viral clearance in only 50-55% (genotype 1) to 80% (genotype 3) of cases. Thus, the development of more efficient treatment regimes with fewer side effects and costs is of high priority. It is generally accepted that the cellular immune response plays the most important role in determining the outcome of HCV infection. Moreover, oxidative stress is considered to be an important pathogenic factor. Zinc is an essential nutrient for a broad range of biological activities. It is necessary for normal liver function, and vice versa the liver plays a central role in zinc homeostasis. Zinc ions are crucial for multiple aspects of the immune system, including the normal development, differentiation and function of cells belonging to both innate and acquired immunity. Among the immune cells that are affected by zinc deficiency, T lymphocytes are noted to have the highest susceptibility. Zinc deficiency causes substantial impairment of cellular immunity, oxidation and damage to DNA. Several studies have investigated the effect of zinc supplementation in chronic HCV patients. Following zinc supplementation, decreases in the incidence of gastrointestinal disturbances, body weight loss and hair loss were found in patients with chronic HCV, along with improved fingernail health. In addition, zinc administered in combination with IFN-α was more effective against chronic HCV than treatment with IFN-α alone. Finally, in addition to the effects of zinc on immune functions and viral defence, its role as an antioxidant may be important in HCV. To conclude, the controlled application of zinc, particularly in a deficient state, is recommended as a complementary therapy for chronic hepatitis C.