Changes in the antioxidant capacity of blood plasma are produced after the ingestion of high doses of fish oil.

Blood plasma shows antioxidant capacity (AOC) due to a number of molecules possessing antioxidant activity. Plasma AOC of young and aged rats fed high doses of fish oil and fish oil + dl-alpha tocopherol was assayed. It was observed that only young rats fed fish oil (with or without antioxidant) show a significant increase in their plasma AOC when compared with controls and with the aged ones. It is suggested that increased AOC results from an adaptive response of animals to the potential risk of oxidative stress due to the increase of membrane polyunsaturation after fish oil ingestion.