What does protein do
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The Multifaceted Role of Protein in the Human Body
Protein and Food Intake Regulation
Satiety and Thermogenesis
Proteins play a crucial role in regulating food intake and body weight. They are more satiating than carbohydrates and fats, which helps in reducing overall food consumption. This satiety effect is partly due to diet-induced thermogenesis, where the body burns more calories to digest protein compared to other macronutrients1 2. Additionally, high-protein diets can limit body weight regain after weight loss by enhancing satiety and increasing energy expenditure1.
Short-term vs. Long-term Effects
In the short term, 'fast' proteins, such as those from animal sources, are more satiating than 'slow' proteins from plant sources. However, in the long term, the satiety and thermogenic effects of protein are sustained regardless of the source1. This makes protein a valuable component in dietary strategies aimed at weight management.
Biological Functions of Proteins
Structural and Functional Roles
Proteins are indispensable for the structure and function of the body. They are involved in maintaining fluid and electrolyte balance, energy production, and pH buffering. Proteins also make up the body's organs, muscles, tendons, ligaments, and bones4 7. They are essential for the building and repair of muscles and the transport of micronutrients, minerals, and oxygen from the lungs to the muscles4.
Enzymatic and Hormonal Functions
Proteins act as enzymes that catalyze biochemical reactions necessary for survival. They are also involved in signal transduction, gene transcription, and cell death. Hormones related to metabolism, such as insulin and glucagon, are protein-based, highlighting their role in metabolic regulation3 4 6.
Immune Function and Cellular Processes
Proteins play a vital role in immune function and various cellular processes. They participate in the body's defense mechanisms and are involved in the synthesis of specific non-protein products like nitric oxide and neurotransmitters3 5.
Nutritional Aspects of Protein
Amino Acid Composition
Proteins are polymers of amino acids, and their nutritional value is determined by their amino acid composition. There are 20 amino acids recognized in our diets, nine of which are essential and must be obtained from food. Animal proteins generally contain all essential amino acids, making them high-quality proteins, while plant proteins may lack one or more essential amino acids5 8.
Protein Turnover and Metabolism
The body constantly synthesizes and degrades proteins, a process known as protein turnover. This turnover exceeds dietary protein intake, indicating a significant degree of recycling. During critical illness or trauma, the synthesis of some non-essential amino acids may be limited, necessitating dietary adjustments to prevent muscle wasting9.
Protein in Cellular Functions
Computational Elements
Beyond their structural and enzymatic roles, some proteins function as computational elements in living cells. They process and transfer information through biochemical 'circuits,' performing tasks like amplification, integration, and information storage6.
Laboratory Studies
Understanding protein function involves studying their domains, binding properties, and how their functions can be altered through post-translational modifications, environmental changes, and mutations. These studies are crucial for developing new therapeutic strategies and functional foods3.
Conclusion
Proteins are indispensable molecules that perform a wide array of functions in the human body, from regulating food intake and body weight to supporting structural integrity and metabolic processes. Their diverse roles underscore the importance of adequate protein intake and the need for ongoing research to fully understand their potential in health and disease management.
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Most relevant research papers on this topic
The significance of protein in food intake and body weight regulation
High protein intake promotes satiety and limits body weight regain after weight loss, while improving metabolic profile and reducing energy intake.
Literature Review
Highly CitedDietary proteins in the regulation of food intake and body weight in humans.
Protein content in food strongly influences short-term satiety and food intake, with potential implications for maintaining healthy body weights.
Literature ReviewHighly CitedUncovering protein function: from classification to complexes
Proteins play diverse roles in living organisms, and their function can be studied in the laboratory through various techniques, including protein binding, post-translational modification, and environmental changes.
Principles of Protein
Proteins are essential for maintaining body structure and function, aiding in energy production, and maintaining fluid and electrolyte balance.
Highly CitedProtein.
Nine essential amino acids are essential for adult humans, while glutamine, glutamate, glycine, proline, and arginine may be conditionally indispensable for specific conditions.
Very Rigorous Journal