Serum Alpha-Tocopherol, Cholesterol, and Total Lipid Values and Unsaturation of Lipids in 33- To 60-Year Old Adults on Self-Selected Diets at Different Levels of Polyunsaturated Fat

The levels and weekly variations of certain lipid components were investigated in healthy adults, 33 to 60 years of age, on self-selected diets under home-living conditions with and without an increased proportion of polyunsaturated fats for a period of 26 weeks. Ten individuals served as controls and 16 were assigned to the experimental diet. Each of the groups contained an equal number of men and women. The experimental diet provided a ratio of polyunsaturated to saturated fatty acids of approximately one, with the substitution of vegetable oils for animal fats within the normal eating patterns of the participants. The control subjects made no dietary changes. Dietary intakes were calculated from records reported by the subjects for two days each week, using a food composition table constructed from all available sources of material. The amount of calories as fat was approximately 38 percent for all subjects. Analyses to determine the alpha-tocopherol, cholesterol and total lipid values, unsaturation of the lipids, and erythrocyte hemolysis were performed on blood collected by finger-tip puncture before breakfast weekly. Serum alpha-tocopherol and cholesterol values were within normal limits at the start of the study. Initial alpha-tocopherol levels for men and women were approximately the same (mean 0.52 mg per 100 ml.) Cholesterol values for women were higher than those for men (201 and 174 mg per 100 ml, respectively). Total lipids were higher in men than in women (767 and 685 per 100 ml, respectively). The experimental diet, consisting of highly unsaturated fats, commercially-available, increased the serum tocopherol slightly decreased the serum total lipids slightly, but had no significant effect upon the serum cholesterol despite a significant increase in dietary P:S ratio and a significant decrease in dietary cholesterol. Erythrocyte hemolysis did not increase in the experimental subjects. No linear relationship was found between serum alpha-tocopherol and erythrocyte hemolysis. The dietary vitamin E: polyunsaturated fatty acid ratio decreased in the experimental group but increased in the control group, the difference between the means being significant. No relationship was found between levels of serum cholesterol and serum tocopherol. Unsaturation of the lipids increased for all subjects, the increase being significant with time but not with the diet. Wide variations in tocopherol and cholesterol were found in sera from the same individual. Increased serum cholesterol levels appeared to coincide with stress or anticipation of stressful situations in several of the subjects