A nutrigenomics view of protein intake: macronutrient, bioactive peptides, and protein turnover.

Proteins are needed for the development and sustainability of life. They are the molecular machines and building blocks in the human body that drive or exert most biological functions and confer structure and function to cell and tissue architecture. Dietary proteins provide essential amino acids and complement lipid and carbohydrate as a major source of energy. Therefore, humans must consume a sufficient amount and quality of proteins to stay healthy and avoid deficiencies. Even with a reasonable amount of intake, variability in protein consumption can result in measurable health consequences in specific conditions. This said, dietary protein delivers more than energy and building blocks to the human body: the pools of body, tissue, and cell proteins, peptides, and amino acids are under complex metabolic control, resulting in a highly dynamic protein turnover, that is, the interplay between synthesis and degradation. Proteins also contain peptide sequences that can be interpreted as bioactive precursors which can be liberated upon digestion to exert biological functions locally (e.g., in the gut) or systemically (i.e., via the bloodstream). In this chapter, we will first review holistic readouts of protein intake assessed by omics technologies such as gene expression, proteomics, and metabolite profiling. Second, we will look at protein benefits beyond macronutrient supply and describe how to generate, analyze, and leverage bioactive peptides. In the third part, we will discuss protein turnover as tackled by proteomics tools that allow single-protein resolution at proteome-wide scale.