Effect of Dietary Amino Acid Profile on Lipoprotein Metabolism, Vascular Reactivity and Inflammatory Markers
Condition: Hyperlipidemias; Metabolic Syndrome X; Cardiovascular Diseases
MeSH terms: Cardiovascular Diseases; Metabolic Syndrome; Hyperlipidemias
Study type: Interventional

Summary: 
      The aim of this study is to explore the significance of the Lys:Arg ratio on responses of
      lipids and lipoprotein concentrations to dietary proteins and to evaluate the effects of
      dietary Lys:Arg on cardiovascular disease risk factors and endothelial function.
    

Detailed description: 
      Findings from early studies in a variety of experimental models of atherosclerosis on the
      effect of dietary protein suggested that proteins from vegetable sources are less
      cholesterolemic and atherogenic than proteins from animal sources. Throughout the later part
      of the 20th century there has been sporadic interest in the effect of protein type and amino
      acid profiles on blood lipid concentrations and atherosclerosis. A major focus for this
      evaluation has been to compare proteins based on their amino acid profile, often expressed as
      lysine (Lys) to arginine (Arg) ratio (Lys:Arg). While animal studies have provided important
      information regarding the significance of the Lys:Arg in determining the cholesterolemic
      response to a dietary protein, interpretation of these data must be done with caution since
      most of the studies have been conducted in animal models that have a different lipoprotein
      distribution and metabolism than humans. Moreover, the mechanistic insights of this response
      are yet to be determined. While the favorable effects of Arg on endothelial function appear
      to be consistent when Arg is administered using a supplement, the effects of dietary Arg
      naturally present in protein rich foods has yet to be determined. The aim of this proposal is
      to explore the significance of the Lys:Arg ratio on responses of lipids and lipoprotein
      concentrations to dietary proteins and to evaluate the effects of dietary Lys:Arg on
      cardiovascular disease risk factors and endothelial function.
    

Intervention name(s): Comparison of dietary protein amino acid profile
Intervention type(s): Behavioral
Intervention description(s): 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.
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Single (Investigator)
Primary purpose: Prevention