Recent advances in dietary proteins and lipid metabolism.

PURPOSE OF REVIEW: There is growing interest in defining the dietary approaches for the management of lipid disorders. This review focuses on dietary proteins.

RECENT FINDINGS: Increasing protein intake was coupled with improved lipid profiles in humans and animals. However, most studies increased the protein content by reducing that of fat or carbohydrate or both, making unclear the role of protein alone. Mechanisms of action differ with the sources of proteins, because of amino acid composition and bioactive peptides encrypted in their sequences. Soy protein was investigated the most, and many studies show that its consumption reduces blood cholesterol. The role of other constituents including isoflavones is debated. Short-term studies are consistent in showing lipid-lowering properties of whey proteins, attributed to their relative high content in branched chain amino acids. A limited number of studies, the majority being on animals, have shown hypocholesterolemic activities of fish proteins.

SUMMARY: Dietary proteins regulate lipid metabolism in a manner dependent on their quantity and composition. There is a general consensus that proteins slow lipid absorption and synthesis, and promote lipid excretion. The benefits of dietary proteins remain to be confirmed in individuals with lipid abnormalities, for formulation of optimal dietary alternatives for the management of lipid disturbances.