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, >or=50 years, LDL cholesterol>or=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.
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