Karin Engström

Effect of fish oils containing different amounts of EPA, DHA, and antioxidants on plasma and brain fatty acids and brain nitric oxide synthase activity in rats

Abstract Background. The interest in n-3 polyunsaturated fatty acids (PUFAs) has expanded significantly in the last few years, due to their many positive effects described. Consequently, the interest in fish oil supplementation has also increased, and many different types of fish oil supplements can be found on the market. Also, it is well known that these types of fatty acids are very easily oxidized, and that stability among supplements varies greatly. Aims of the study. In this pilot study we investigated the effects of two different types of natural fish oils containing different amounts of the n-3 PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and antioxidants on plasma and brain fatty acids, blood lipids, vitamin E, and in vivo lipid peroxidation, as well as brain nitric oxide synthase (NOS) activity, an enzyme which has been shown to be important for memory and learning ability. Methods. Sprague-Dawley rats were divided into four groups and fed regular rat chow pellets enriched with 5% (w/w) of butter (control group), a natural fish oil (17.4% EPA and 11.7% DHA, referred to as EPA-rich), and a natural fish oil rich in DHA (7.7% EPA and 28.0% DHA, referred to as DHA-rich). Both of the fish oils were stabilized by a commercial antioxidant protection system (Pufanox®) at production. The fourth group received the same DHA-rich oil, but without Pufanox® stabilization (referred to as unstable). As an index of stability of the oils, their peroxide values were repeatedly measured during 9 weeks. The dietary treatments continued until sacrifice, after 10 days. Results. Stability of the oils varied greatly. It took the two stabilized oils 9 weeks to reach the same peroxide value as the unstable oil reached after only a few days. Both the stabilized EPA- and DHA-rich diets lowered the triacylglycerols and total cholesterol compared to control (-45%, P < 0.05 and -54%, P < 0.001; -31%, P < 0.05 and -25%, P < 0.01) and so did the unstable oil, but less efficiently. Only the unstable oil increased in vivo lipid peroxidation significantly compared to control (+40%, P < 0.001). Most of the fatty acids in the plasma phospholipids were significantly affected by both the EPA- and DHA-rich diets compared to control, reflecting their specific fatty acid pattern. The unstable oil diet resulted in smaller changes, especially in n-3 PUFAs. In the brain phospholipids the changes were less pronounced, and only the diet enriched with the stabilized DHA-rich oil resulted in a significantly greater incorporation of DHA (+13%, P < 0.01), as well as total n-3 PUFAs (+13%, P < 0.01) compared to control. Only the stabilized DHA-rich oil increased the brain NOS activity (+33%, P < 0.01). Conclusions. Both the EPA- and DHA-rich diets affected the blood lipids in a similarly positive manner, and they both had a large impact on plasma phospholipid fatty acids. It was only the unstable oil that increased in vivo lipid peroxidation. However, the intake of DHA was more important than that of EPA for brain phospholipid DHA enrichment and brain NOS activity, and the stability of the fish oil was also important for these effects.

Whole blood production of thromboxane, prostacyclin and leukotriene B4 after dietary fish oil supplementation in man: effect of vitamin E.

12 subjects were given 30 ml/day of a fish oil already stabilized with vitamin E (1.5 IU/g) and other natural antioxidants (fish oil, FO), and the same fish oil supplemented with extra vitamin E (to total 4.5 IU/g) (FO+E), in a randomized double-blind cross-over study. The whole blood production of thromboxane B2, measured in serum, was reduced after 4 weeks of ingestion of both FO+E (by 47%, P < 0.01) and of FO (by 40%, P < 0.05) whereas 6-keto-PGF1 alpha increased slightly in both cases, by 4% and 5% respectively, both NS. Leukotriene B4 production decreased on both FO+E (by 20%, NS) and FO (by 17%, P < 0.05). This study thus showed that a stabilized fish oil had marked effects on eicosanoid production, which may be important for its cardiovascular effect. Further supplementation with vitamin E had no additional effect, indicating that the vitamin E content (1.5 IU/g) in this stabilized fish oil might have been optimal.

Effect of in vitro Stability of Dietary Fish Oil on Lipid Peroxidation and Prostanoids in vivo

Dietary supplementation of rats with fish oil for 18 days resulted in signs of lipid peroxidation, with increased malondialdehyde production in plasma and myocardium. This increase in malondialdehyde could be completely prevented by supplementing the fish oil with a new natural antioxidant mixture (Pufanox) which is known to markedly increase the in vitro stability of fish oils. Addition of Pufanox to fish oil also tended to increase the ratio between the vasodilator prostacyclin and the vasoconstrictor thromboxane A2. The concentration of vitamin E decreased, both in plasma and in the heart after the period of fish oil ingestion, indicating that the fish oil used contained too little vitamin E. Plasma cholesterol and triglyceride levels decreased markedly after fish oil supplementation but with no apparent difference between fish oil with or without Pufanox, probably due to the insufficient content of vitamin E. The results obtained emphasize the importance both of the in vitro stability of the fish oil given and of the amount of vitamin E added.

Hazards with electrocautery-induced decomposition of fatty acids : in view of lipid embolization

Abstract Objectives. Electrocautery is an appreciated surgical tool, which however, generates immense heat and fat-tissue melting. In cardiac surgery, liquefied fat collects on the surface of blood in the pericardial cavity and becomes aspirated by the heart-lung machine for aortic recycling. Deposits seen in the brain microcirculation after surgery are caused by lipid embolism. This study investigates lipid chemistry, whether heat from electrocautery generates fatty-acid fragmentation and decomposition. Design. Pericardial fat tissue was sampled from cardiac-surgery patients and from piglets. The human tissue was exposed to electrocautery, or to fixed temperatures in an in vitro model. Fatty-acid decomposition was explored by solid-phase microextraction gas chromatography and the distribution of fatty acids was measured. Results. Fatty-acid decomposition demonstrated a temperature-effect relationship (p=0.007). At 350°C the proportion of polyunsaturated fatty acids became heavily reduced or were abolished (p=0.016). Electrocautery resulted in similar changes. Conclusions. Electrocautery induces a profound fatty-acid fragmentation to form short-chained compounds. The chemical and toxic nature of these compounds remains to be determined, including their clinical implications at blood recycling in cardiac surgery.