**7. Effect of fish oil (Omega3) and olive oil on membrane fluidity, ATPase activity in relapsing‐remitting multiple sclerosis.**

The mechanism of action for omega‐3 PUFAs is suggested to be attributed to immunomodu‐ lation and antioxidant action [24]. For instance, omega‐3 PUFAs decrease the production of inflammatory mediators (eicosanoids, cytokines, and ROS) and the expression of adhesion molecules. They both act directly by replacing AA as an eicosanoid substrate and inhibiting AA metabolism and indirectly by altering the expression of inflammatory genes through effects on transcription factor activation. Omega‐3 PUFAs also give rise to anti‐inflammatory mediators (resolvins and protectins) [25]. Effects of resolvins and protectins include reducing neutrophil trafficking, cytokine, and ROS regulation and lowering the magnitude of the inflammatory response [26].

Previously, we developed a twelve‐month randomized double‐blind controlled clinical trial in 50 patients with relapsing‐remitting MS. Patients received an oral dose of 4 g/day of fish oil (containing a total of 800 mg of EPA and 1600 mg of DHA) or olive oil. Fasting blood samples were collected at baseline and after 6 and 12 months of the trial, in order to evaluate the effect of consumption of omega‐3 PUFAs on some markers of oxidative stress at the peripheral level. The initial findings of this work were the decrease in serum levels of TNFα, IL‐1β, IL‐6, and nitric oxide metabolites compared with the placebo group [27].

On the other hand, after 12 months of intervention, supplementation with omega‐3 PUFAs significantly enhanced the quantities of serum omega‐3 highly unsaturated fatty acids compared with baseline values. Additionally, the levels of medium‐chain monounsaturated fatty acids were significantly decreased. The olive oil supplementation induced minor decreases in EPA and DHA levels after 12 months of intervention. There were significant increases in both EPA and DHA in the group given fish oil supplementation compared to the control group receiving olive oil. These increases were associated with a concomitant decrease in AA. Consequently, the omega‐3 fatty acid index in the fish oil group increased significantly, and the ratios of n‐6/n‐3 and AA/EPA were decreased [28].

No differences in glutathione reductase activity and content of reduced glutathione, oxidized glutathione, and oxidized/reduced glutathione ratio were seen after 12 months of supplemen‐ tation with omega‐3 PUFAs. However, a trend in favor of omega‐3 PUFAs supplementation was observed in GSSG levels and glutathione reductase activity at 12 months of intervention between the study groups [28].

A steady decrease in mitochondrial ATPase activity in platelets was observed in the groups given omega‐3 fatty acid and the control group receiving olive oil. Membrane fluidity of platelets was significantly reduced in MS patients. Interestingly, a significant increase in platelet membrane fluidity was observed in the groups receiving omega‐3 fatty acid and the control group receiving olive oil. As well, the fluidity of erythrocyte membranes was un‐ changed for both treatments (Unpublished results).

Epidemiological and experimental studies suggest an increased incidence of MS in popula‐ tions with a high intake of saturated fats mainly from animal sources. Therefore, by consuming a diet high in fatty acids, without an appropriate number of unsaturates, a shift is produced in the integrity and functionality of the membrane [29]. An optimal balance in the consumption of fatty acids includes 35% polyunsaturated fatty acids and 65% saturated fatty acids, and the appropriate proportion of PUFA to maintain membrane balance is 50% omega‐3 with 50% omega‐6. The above ratio was a factor that inactivated the CD4 autoreactive cells in the CNS, a phenomenon that prevents the production of proinflammatory cytokines and free radicals [30].

Membrane fluidity depends on the temperature, the ratio of saturated/PUFA fatty acids, the presence of "lipid rafts," and the proportion of cholesterol present at the membrane [31]. Previous studies in patients with rheumatoid arthritis had increased cell membrane rigidity compared to membranes from those receiving immunomodulatory treatment. Our results showed diminished platelet membrane fluidity in MS patients and that proper membrane fluidity is restored with treatment of omega3 PUFAs. The increase in platelet membrane fluidity is directly related to the incorporation of PUFA's. Furthermore, the increase in membrane fluidity is accompanied with a significant decrease in mitochondrial ATPase activity. This ensures that the activity of ATP synthesis in mitochondria remains elevated.
