ASSOCIATION OF DIET QUALITY WITH ANTIOXIDANT CAPACITY OF PLASMA OF WOMEN WITH BREAST CANCER BEFORE AND AFTER ANTINEOPLASTIC TREATMENT

Background and objectives: Reactive oxygen species (ROS) are important in regulating normal cellular processes, but deregulated ROS contributes to the development of diseases, including cancers. In addition to maintain body weight, a balanced diet rich in antioxidant nutrients can positively affect the effectiveness of antineoplastic treatment by reducing the physiological and oxidative damage caused by treatment. It is suggested that a diet rich in fats can stimulate lipid peroxidation, favoring the increase of ROS in cancer patients. The objective of this study was to verify the association between diet quality and antioxidant capacity of plasma in women with breast cancer before and after antineoplastic treatment. Methods: Sociodemographic, clinical, anthropometric and therapeutic data of 70 women were collected. Food consumption was assessed by food frequency questionnaire. The diet quality was evaluated using the Brazilian Healthy Eating Index Revised (BHEI-R) and its components. The antioxidant capacity of plasma was evaluated biochemically from the determination of iron reducing antioxidant potential (FRAP). Food consumption assessment and antioxidant capacity of plasma were conducted before and after the treatment. Multiple linear regression was used to assess the relationship between diet quality and FRAP before and after treatment. Logistic regression model was used to verify the association between change in diet quality and change in FRAP during treatment. Results: The median total score of the BHEI-R before and after treatment was similar (p=0.684) (median=76.2 e 76.5, respectively). No association was found between the FRAP before and after treatment (μ=629.5, DP=19.1 and μ=573.8, DP=22.7, respectively p=0.051). Patients classified in the third tertile of diet quality (better quality) significantly increased the FRAP (β=106.78, p=0.019) before the treatment, however no association was found after the treatment. In prospective analyses, the association between change in diet quality and change in FRAP was not statistically significant (p= 0.260). Conclusions: Women with breast cancer with better quality of diet had better concentrations of plasma antioxidants before treatment. However, the diet did not change the antioxidant capacity of plasma after treatment. Increase quality of diet is not enough to improve the antioxidant capacity of plasma in patients undergoing treatment for breast cancer in this sample of Brazilian women.