LONG-TERM EFFECTS OF DIETARY MONOUNSATURATED AND POLYUNSATURATED FATTY-ACIDS ON THE LIPID-COMPOSITION OF ERYTHROCYTE-MEMBRANES IN DOGS

1. Lipid analyses were conducted on erythrocyte membranes from dogs fed for 6 months with a normal defatted diet supplemented with either olive or sunflower oil. 2. Levels of palmitic. stearic and arachidonic acids were only slightly affected by dietary fat. 3. The unsaturated fatty acids of n-9 series were elevated in all the phospholipid fractions analysed for olive oil-fed dogs while the n-6 fatty acids, with the exception of arachidonic acid, were elevated in sunflower oil-fed dogs. 4. In the olive oil group the 20:5 (n-3) acid was higher than in the sunflower oil group. 5. The unsaturation index and the cholesterol/phospholipid ratio increased along the time course in the sunflower oil group. Both increases are complementary in order to maintain the constant fluidity of membranes.