Abstract
In a dietary supplementation study of 30 subjects with early Alzheimer's disease [1], 15 received evening primrose oil plus zinc sulphate plus sodium selenite and 15 received olive oil. We have now looked at the effects of the supplements on the lipid abnormalities noted in the patients. The proportion of saturated fatty acids in plasma phospholi-pids was reduced after supplementation while the more unsaturated red cell (RBC) membrane phospholipids showed no change, i.e. the relative unsaturation of the red cell phospholipids was not altered by the dietary supplementation that significantly reduced the saturation of the plasma phospholipids. There may thus be a defect of fatty acid incorporation into the red cell membrane phospholipids or an unidentified abnormality of the structure which leads to the altered fatty acid constitution without altered fluidity, as other studies have found no change in the fluidity of the RBC membranes in Alzheimer's disease. Impaired uptake of cholesterol by the erythrocyte is the hypothesis favoured and the possible effects of impaired uptake of cholesterol by the brain are considered. Reduced cholesterol accumulation may coexist with increased lipid peroxi-dation and study of the relationship of the two processes may be valuable. Although the dietary supplements were designed to be antioxidant, their benefit may have derived from delivery of lipids to tissues, and strategies for increasing the delivery of cholesterol to the brain should be identified.