Dietary Modification of Membrane Phospholipids in Breast Disease.

An investigation was made into the effect of different dietary fats (com oil, olive oil and MaxEPA) on membrane phospholipids (phosphatidylinositol, phosphatidylcholine and phosphatidylethanolamine) in the rat mammary gland and red blood cells. It was demonstrated that phosphatidylinositol is the least responsive phospholipid to dietary fatty acid modification in both of the tissues studied. Overall, erythrocytes responded to the different diets more than mammary gland membranes. Phosphatidylethanolamine incorporated more w3 fatty acids from the marine oil diet than either phosphatidylcholine or phosphatidylinositol. The arachidonic acid (20:4w6) content of phosphatidylcholine and phosphatidylethanolamine was highest in animals fed com oil, less in animals fed olive oil and the least in those fed marine oil. The relative proportions of phospholipids in the mammary gland and red blood cell membranes were not affected by feeding rats different diets. It was also demonstrated that the fatty acid profile of phospholipids from rat, N-ethyl-A-nitrosourea (ENU) induced mammary tumours are not very different to those from normal rat mammary tissue. However, in the phosphatidylinositol fraction, in rats on all three diets the stearic acid content was higher in the tumours than in the normal mammary tissue. This was most evident in the olive oil group (12 mol%; p<0.05) and least in the marine oil group (<3 mol%; NS). Rats administered ENU and fed a MaxEPA diet presented with fewer mammary tumours than those fed either a corn oil diet or an olive oil diet (p<0.05). Possible mechanisms for the protective effect of marine oil on mammary tumourigenesis are discussed. The effect of a low fat diet on human female erythrocyte membrane phospholipids was studied. Only a few changes to membrane phospholipids were demonstrated. There was no significant effect on the fatty acid profile of phosphatidylcholine after two months of a low fat diet; and there was only a small change in the phosphatidylinositol fraction (increased arachidonic acid [20:4w6], p<0.05). Serum prolactin and oestradiol were also measured in this study. There was no effect of diet on prolactin levels as measured by radioimmunoassay. However, there was a significant decrease in serum oestradiol (p