Effects of Dietary Protein Quantity, Source, and Type on Plasma Lipids and Lipoproteins and Their Roles in...

Evidence from clinical trials indicates that dietary protein plays an important and often underappreciated role in lipoprotein lipid metabolism. For this narrative review, literature searches were conducted in the PubMed and Cochrane Central Register of Controlled Trials databases for articles describing randomized controlled trials (RCTs) and systematic reviews and meta-analyses of RCTs, as well as dietary guidelines and dyslipidemia management recommendations, using search terms for protein quantity, source (e.g., animal- and plant-based), and type (e.g., dairy, meat, soy, and nuts) and effects on lipids and lipoproteins in humans. Findings indicated that dietary intakes of both animal-based and plant-based proteins, when replacing refined carbohydrates or saturated fatty acids, lower circulating concentrations of atherogenic lipoproteins. Protein from plant sources appears to produce a somewhat larger effect on lipoprotein lipid concentrations than protein from animal sources. Individual amino acids (e.g., branched-chain amino acids), protein food fractions (e.g., whey), and food-derived peptides may independently impact lipoprotein lipid metabolism. Beyond the effect of replacing one macronutrient for another, the biochemical pathways responsible for the effects of dietary protein on lipoprotein lipid metabolism in humans have not been fully defined. The importance of dietary protein in a healthy diet is emphasized in recent dietary recommendations for the general population and for individuals with dyslipidemias. Additional research is warranted to determine the amount of dietary protein and the best balance of food source(s) to optimize its benefits on lipoprotein lipid concentrations, as well as the mechanisms for these effects.