Background and purpose: Free radicals have important role in many diseases such as cancer. Antioxidants are powerful scavengers of free radicals and help immune system to remove them. Total antioxidant capacity (TAC) indicates total antioxidant activity in plasma and body fluids. Imbalance between producing free radicals and antioxidant defense leads to oxidative stress in the body and results in cell components damage. Lipid oxidative damage caused by free radicals produces active aldehydes such as malondialdehyde (MDA). This study aimed at investigating the effect of consumption of grape -an antioxidant-rich fruit- on serum levels of MDA and also evaluating the indicators of oxidative stress. Materials and methods: This study was conducted in 43 overweight women in Joorab village, Malayer, Iran, who were selected via simple random sampling in 2015. The relationship between BMI and age were assessed with serum MDA and TAC levels. Considering the significant relationship between MDA and TAC with BMI and age, the study population was divided into three groups: BMI1 (over weight), BMI2 (obese), and BMI3 (sever obesity). MDA and TAC levels were evaluated using HPLC and ELISA in three groups after two consecutive weeks of grape-free diet and consumption of fresh grapes. Results: Grape consumption significantly reduced serum MDA level in BMI2 and BMI3 groups (P<0.05 and P<0.001, respectively) but did not have considerable effect on MDA level among those in BMI1. Also, consumption of grape had no significant effect on TAC level (P>0.05). Conclusion: Grape consumption could reduce oxidative stress markers and improve antioxidant defense.
