Fish oil prevents change in arachidonic acid and cholesterol content in rat caused by dietary cholesterol.

Rats were fed diets high in either saturated fat (beef tallow) or alpha-linolenic acid (linseed oil) or eicosapentaenoic and docosahexaenoic acids (fish oil) with or without 2% cholesterol supplementation. Consumption of linseed oil and fish oil diets for 28 days lowered arachidonic acid content of plasma, liver and heart phospholipids. Addition of 2% cholesterol to diets containing beef tallow or linseed oil lowered 20:4 omega 6 levels but failed to reduce 20:4 omega 6 levels when fed in combination with fish oil. Feeding omega 3 fatty acids lowered plasma cholesterol levels. Addition of 2% cholesterol to the beef tallow or linseed oil diet increased plasma cholesterol concentrations but not when fish oil was fed. Feeding the fish oil diet reduced the cholesterol content of liver, whereas feeding the linseed oil diet did not. Dietary cholesterol supplementation elevated the cholesterol concentration in liver in the order: linseed oil greater than beef tallow greater than fish oil (8.6-, 5.5-, 2.6-fold, respectively). Feeding fish oil and cholesterol apparently reduced 20:4 omega 6 levels in plasma and tissue lipids. Fish oil accentuates the 20:4 omega 6 lowering effect of dietary cholesterol and appears to prevent accumulation of cholesterol in plasma and tissue lipids under a high dietary load of cholesterol.