Altering dietary lysine:arginine ratio has little effect on cardiovascular risk factors and vascular reactivity in moderately hypercholesterolemic adults

Background: Information is scarce regarding the effect of dietary protein type, with specific focus on the lysine-to-arginine (Lys:Arg) ratio, on cardiovascular risk factors and vascular reactivity in humans. Objective: Determine the effect of dietary Lys:Arg ratio on cardiovascular risk factors and vascular reactivity in moderately hypercholesterolemic adults. Design: Randomized cross-over design of two 35-day diet phases; thirty adults (21 females and 9 males, ≥50 years, LDL cholesterol ≥120. mg/dL). Diets had 20% energy (E) protein, 30%. E fat, 50%. E carbohydrate and were designed to have low (0.7) or high (1.4) Lys:Arg ratio. Measures included fasting and postprandial lipid, lipoprotein, apolipoprotein concentrations; fasting high sensitivity C-reactive protein (hsCRP), small dense LDL (sdLDL) cholesterol, remnant lipoprotein cholesterol (RemLC), glycated albumin, adiponectin and immunoreactive insulin concentrations, endogenous cholesteryl ester transfer protein (CETP) and lecithin:cholesterol acyl transferase (LCAT) activities; cholesterol fractional synthesis rate (FSR); and flow mediated dilation (FMD) and peripheral artery tonometry (PAT). Results: No differences were observed in fasting and/or postprandial total, LDL, HDL and sdLDL cholesterol, RemLC, Lp(a) or apo B concentrations, LCAT and CETP activities, FSR, glycated albumin, immunoreactive insulin, FMD or PAT. The low, relative to the high, Lys:Arg ratio diet resulted in lower postprandial VLDL cholesterol (-24%, P= 0.001) and triglycerides (-23%, P= 0.001), and small but significant differences in fasting (-3%, P= 0.003) and postprandial (-3%, P= 0.018) apo AI, and fasting adiponectin concentrations (+7%, P= 0.035). Fasting and postprandial hsCRP concentrations were 23% lower after the low Lys:Arg ratio diet (P= 0.020 for both). Conclusions: Diets differing in Lys:Arg ratios had no or small effects on cardiovascular risk factors and vascular reactivity.