THE EFFECT OF ZINC-DEFICIENCY ON ERYTHROCYTE-MEMBRANE LIPIDS OF FORCE-FED RATS RECEIVING A DIET CONTAINING COCONUT OIL OR FISH-OIL

In the present study, the effect of zinc deficiency on erythrocyte mem brane lipids of force-fed rats that received either a diet with coconu t oil and safflower oil (86:14, w/w) or a diet with fish oil and saffl ower oil (91:9, w/w) was investigated. Zinc deficiency caused in the r ats fed both types of dietary fat an increase in the amounts of total phospholipids and individual phospholipid classes in erythrocyte membr anes. In the rats fed the coconut oil diet, zinc deficiency caused an increase in the proportion of docosahexaenoic acid (22:6) in phosphati dylcholine (PC), diacyl phosphatidylethanolamine (PE), phosphatidylser ine (PS), and in total erythrocyte membrane fatty acids. In contrast, in the rats fed the fish oil diet, zinc deficiency caused an increase in the proportion of docosahexaenoic acid only in PC, but not in the o ther phospholipids. However, in these rats, changes in the ratio betwe en eicosapentaenoic acid (20:5) and the n-3 fatty acids with 20 and 22 carbon atoms were observed in PC, diacyl PE and plasmalogen PE. The m ost pronounced changes in fatty acid composition due to zinc deficienc y in the rats fed both types of fat occured in PC, There was a relatio nship between the changes in the composition of plasma total fatty aci ds and the changes in fatty acid composition of erythrocyte membrane P C caused by zinc deficiency in the rats fed both types of dietary fat. The amount of cholesterol was similar in all treatment groups. Howeve r, zinc-deficient rats fed the coconut oil diet - but not those fed th e fish oil diet - had an increased ratio between total phospholipids a nd cholesterol. Thus, the study shows that the effect of zinc deficien cy on erythrocyte membrane lipids is to some degree similar for rats f ed a coconut oil diet and rats fed a fish oil diet, and to some degree different.