Beneficial effects of fish intake on serum lipids and adipokines

[Objectives] n-3 polyunsaturated fatty acids (PUFA) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) which are known to prevent atherosclerosis are present in large amounts in blue-fish such as mackerel, horse mackerel and pacific saury. People who have low serum EPA are reported to have a high incidence of coronary artery diseases (CAD). Administration of EPA or DHA as a supplement significantly increased serum level of EPA which lowered the incidence of CAD. [Materials and Methods] Eight healthy female university students aged 22 years were enrolled in this study. They were instructed to take 80 g of blue-fish of any kind during lunch time for two weeks without changing other lifestyle including breakfast and supper. After the experimental period, they were told to return to the previous diet. The venous blood was taken from the median cubital vein before and after the experimental period, and two weeks after the end of the experiment. Then the serum lipids and adipokines levels were measured. [Results and Findings] Two weeks fish intake significantly decreased serum triglyceride (TG) without affecting total cholesterol and high-density lipoprotein cholesterol levels. The fish intake also significantly increased serum n-3 PUFA such as EPA, DHA whereas it significantly decreased n-6 PUFA such as linoleic acid, gamma linoleic acid and dihomo-gamma-linoleic acid. These changes were reversed by the previous diet for two weeks. Regarding the adipokines, fish intake showed an increase in serum adiponectin levels from 8.65 +- 0.33 micro g / ml to 9.53 +- 0.71 micro g / ml although the increase was not statistically significant. Serum TNF alpha levels were not affected by the fish intake. Dietary survey revealed that those who take large amount of EPA in diet have significantly high concentration of serum EPA. In the case of DHA, the relation between dietary intake and serum DHA was not statistically significant. [Conclusion] Eighty grams of blue-fish intake once a day showed beneficial effects on serum TG and fatty acids. However, discontinuation of fish intake cancelled the beneficial effects in two weeks.