Background & Objectives: Consumption of ω3 fatty acids supplementation inhibits oxidative stress injury, increases activity of antioxidant enzymes and decreases lipid peroxidation in gastric cancer patients. In this study, we examined effects of ω-3 fatty acid intakes on oxidative stress in gastric cancer patients undergoing chemotherapy.

  Methods: This double blind clinical trial study was conducted on 30 adult patients (15 cases and 15 controls) with gastric cancer during chemotherapy in Ardabil city in 2010. Case and control groups were selected by randomized allocation. Three grams ω -3 fatty acid supplementation (1.8 g EPA & 1.2 g DHA in 10 g fish oil) and placebo were given case and control groups for 45 days, respectively. Anthropometric indices (weight, height & BMI) were measured. Blood samples were taken and then biochemical factors including triglycerides, total cholesterol, HDL and LDL cholesterol, MDA, and total antioxidants were evaluated at the beginning, middle and end of the study . The data were analyzed by using Paired sample t-test, Independent sample t-test and repeated measures test.

  Results: MDA, Weight and BMI of omega group after intervention were significantly more than control group at the end of the study (p<0.05). Weight and BMI were decreased but serum MDA was significantly increased in control group during the study (p<0.05). Weight, BMI , and total antioxidants were significantly increased in omega group during day 30-45, (p<0.05). There were no significant differences in other biochemical factors at the end of study.

  Conclusion: The present investigation shows administration of ω3 fatty acid supplements to gastric cancer patients during chemotherapy increases the total antioxidants capacity and prevents the enhancement of oxidative stress.