Effects of long-term consumption of high doses of fish oil concentrates on clinical parameters in male and female rats

Many studies suggest that a diet supplemented with fish oil concentrates (FOCs) may provide protection against cardiovascular and other diseases. The possible harmful effects of long-term consumption of high doses of FOCs, however, have not been adequately investigated. Corn oil, fish oil (MaxEPA) and various mixtures of the oils were administered by gavage to 120 male and 120 female rats, 5 d/wk for 13 wk at the rate of 5 mL/kg/d. Although MaxEPA had no effect on prothrombin time or activated partial thromboplastin time, it caused a statistically significant diminution of the total serum cholesterol level. Correlations between relative liver and spleen weights and dose levels were positive but a negative correlation was found between dose levels and serum vitamin E concentration. In female rats, the negative correlations between dose levels and serum iron and triglyceride levels were highly significant. The pathology data showed no remarkable lesions in any of the tissues examined. Results of this study suggest that long-term consumption of high levels of FOCs in rats may reduce serum cholesterol and triglycerides and adversely affect serum iron level and relative liver weight in female rats and relative spleen weights in both sexes.