Sodium transport kinetics, cell membrane lipid composition, neural conduction and metabolic control in type 1 diabetic patients - Changes after a low-dose n-3 fatty acid dietary intervention

Background: A decreased content of n-3 fatty acids in erythrocyte membrane of type 1 diabetic patients, which is inversely related to plasma levels of HbA(1c), has been reported previously. Our aim in this study was to observ e the changes after a low-dose n-3 fatty acid (330 mg/day docosahexaenoic a cid and 630 mg/day eicosapentanoic acid) dietary intervention in the lipid composition of cell membrane and metabolic control (measured according to p lasma HbA(1c) levels). Since changes in both parameters may alter transmemb rane sodium transport or influence parameters measuring target organ damage , we also studied the neural conduction duality and activity of four sodium transporters. Methods: Eighteen type 1 diabetic patients were randomly ass igned to continue their usual diet (control group) or to supplement their d iet with a daily low dose of n-3 fatty acids (supplemented group). The chan ges between baseline and end values of the following parameters were compar ed: HbA(1c), lipid and phospholipid composition of cell membrane, activity of four ion carriers and neural conduction quality. Results: The dietary su pplementation caused statistically significant changes in membrane lipid co mposition, particularly an increase of C22:6 (n-3) and the total n-3 fatty acid (respectively +0.90 +/- 1.14% vs. -0.44 +/- 1.23% and +1.36 +/- 1.62% vs. -0.5 +/- 1.80%, p < 0.05). After the dietary supplementation, we also o bserved a significant decrease of HbA(1c) (-2.00 +/- 1.9% vs. -0.13 +/- 0.4 8%, p < 0.05),without significant changes in the dose of insulin required, an increase in the motor conduction velocity by the median nerve (+2.12 +/- 1.35 mis vs. -0.8 +/- 2.34 mis, p < 0.05) and a decrease of the V-max of t he Na+-Li+ counter-transport (-96.6 +/- 111.2 vs. +58.1 +/- 81.3 mu mol/l c ell/h(-1), p < 0.01). Conclusion: A low-dose omega-3 fatty acid dietary sup plementation may change the fatty acid composition of the cell membrane and improve the metabolic control of diabetes. Using this dose, we also observ ed a decrease of the maximal rate of Na+-Li+ countertransport and a slight improvement of neural conduction.