Background: Walnuts and fatty fish contain high amounts of polyunsaturated fatty acids, which have been shown to decrease the incidence of cardiovascular disease. Walnuts and fatty fish also contain other nutrients, such as antioxidants, that contribute to the reduction of cardiovascular disease.
Objective: The purpose of the present study was to compare the effects of dietary walnuts and fatty fish on the plasma and urine oxygen radical absorbance capacity (ORAC) values.
Material and method: Twenty-five subjects participated in this randomized 3 x 3 crossover study, which was performed under controlled metabolic feeding conditions. Subjects consumed 3 isoenergetic diets and each diet was consumed for 4 weeks: a control diet (no nuts or fish), a walnut diet (1.5 oz/day of walnuts, 6 times/week) and a fish diet (8 oz/week of salmon). Blood specimens were collected at baseline and at the end of each diet period.
Results: The results showed that the plasma hydrophilic ORAC was significantly higher in the walnut diet compared with the control diet and the fish diet (p < 0.0001). In addition, the urine ORAC was significantly higher in the walnut diet and the fish diet compared with the control diet (p < 0.0001). Moreover the hydrophilic/lipophilic ORAC for the food itself was significantly higher in the walnut diet compared with the control diet and the fish diet (p < 0.0001).
Conclusion: The present results suggest that walnuts have a large antioxidant capacity; therefore, including walnuts in the daily diet may be beneficial to maintain an antioxidant status in the body.