What are proteins?

Proteins are one of the fundamental building blocks of life. They are complex molecules present in every cell of our body and play a crucial role in a variety of biological functions.

In this session, we will explore in detail what proteins are, their importance in nutrition and how they influence overall health and well-being.

Definition of Proteins

Proteins are macromolecules made up of linear chains of amino acids. These are the fundamental building blocks of proteins and there are twenty different types of amino acids that combine in various sequences to form a wide variety of proteins with different functions.

Functions of Proteins

Proteins play an essential role in our body:

• Structural: They are essential components of cellular tissues and structures, such as keratin in hair and nails, or collagen in skin and bones.

• Enzymatic: They act as enzymes that accelerate chemical reactions in the body, facilitating processes such as digestion and metabolism.

• Transport: Some proteins transport molecules through the blood, such as hemoglobin, which carries oxygen to the cells.

• Defense: Antibodies are proteins that are part of the immune system and help fight infection and disease.

• Regulation: They regulate cellular activity and gene expression, acting as molecular switches.

• Muscle contraction: Muscle proteins such as actin and myosin are responsible for muscle contraction.

• Storage: They store essential nutrients such as iron and oxygen in muscles and liver.

Protein Sources

Protein sources come from a variety of foods:

• Proteins of Animal Origin: Meat, fish, eggs, dairy products and poultry are rich in complete proteins, containing all the essential amino acids.

• Vegetable Proteins: Legumes, nuts, seeds, tofu and soy products are sources of vegetable proteins and often require combinations to obtain essential amino acids.

• Protein Complementation: Combining different plant protein sources can create a complete protein, such as rice with lentils.

Importance of Proteins in Nutrition

Proteins are essential in the diet for several reasons:

• Growth and Repair: They are crucial for tissue growth and repair, especially in children and adolescents.

• Maintenance: They maintain muscle mass and other tissues in adults.

• Enzyme Synthesis: They participate in the synthesis of enzymes that regulate metabolic processes.

• Hormone Synthesis: They help in the synthesis of hormones such as insulin and glucagon.

• Satiety Sensation: Proteins promote a feeling of satiety, which can help control appetite and weight.

Protein Requirements

Protein requirements vary according to age, sex, physical activity and other individual factors. In general, it is recommended that protein account for approximately 10-35% of total daily calories. However, health professionals or dietitians should be consulted to determine the specific needs of each individual.

Excess Protein and Side Effects

Excess protein can have negative side effects, such as increased kidney burden, dehydration, and stress on the liver. It can also contribute to weight gain if consumed in excess and stored as body fat.

Protein Deficiency and Consequences

Protein deficiency can lead to a number of health problems, such as loss of muscle mass, weakness, fatigue, stunted growth in children, edema, and compromised immune function.