Effect of Dietary Amino Acid Profile on Lipoprotein Metabolism, Vascular Reactivity and Inflammatory Markers

Healthy adults over 50 years of age (men and postmenopausal women) will be assigned to one of two diets differing in lysine to arginine ration (0.7 vs. 1.4) for a 5 week period and then switched to the alternate diet, with a 2 to 4-week washout period, in a randomized crossover design. Blood samples will be collected three times in the fasted state and once 4-hours after the evening meal during the last week of each dietary period of measurement of concentration of plasma lipids, lipoproteins, apolipoproteins, arginine, C-reactive protein, nitrites/nitrates, homocysteine, lecithin-cholesterol acetyltransferase (LCAT), cholesteryl ester transfer protein (CETP), and LDL-receptor messenger ribonucleic acid (mRNA) expression.A 24-hour urine sample will be collected at the end of each phase to measure F2-isoprostanes as an indicator of whole body oxidation.