Proteins

Structure: from Amino Acids to Proteins

Proteins are built from 20 Amino Acids, 9 of which are classified as Essential because the body cannot synthesize them on its own and they must be obtained through diet or supplementation: Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, and Valine. The remaining 11 are Nonessential or Conditionally Essential, meaning they can be synthesized under normal conditions, but their production may become insufficient during periods of Physical Stress, Illness, or Nutritional Deficiency.

The sequence in which Amino Acids are arranged along the chain — known as the Primary Structure — determines the three-dimensional shape of the Protein and, consequently, its specific biological function. Even a single change in the sequence can profoundly alter a Protein’s activity.

Classification of Proteins

Based on their Amino Acid profile, the following are distinguished:

• Complete Proteins — contain all 9 Essential Amino Acids in adequate proportions. Typically of animal origin: Eggs, Meat, Fish, Dairy Products, and Whey. Among plant-based sources, Soy and Quinoa are complete.
• Incomplete Proteins — lacking one or more essential Amino Acids. Typically found in Legumes, Grains and Pseudograins. A complete profile is achieved by combining different sources (e.g., Rice + Peas).

Biological Functions

Proteins play an extremely diverse range of biological roles:

• Structural — Marine collagen and keratin form the structural framework of connective Tissue, Skin, Hair, Bones and Cartilage
• Enzymatic — Enzymes are Proteins that catalyze all of the body’s Metabolic Reactions
• Immune — Antibodies are Glycoproteins produced by the Immune System in response to Pathogens
• Transport — Hemoglobin transports oxygen in the blood; Albumin transports Lipids, Hormones, and Drugs
• Hormonal — Insulin, Glucagon, and GH are Proteins that function as Metabolic signaling molecules
• Contractile — Actin and Myosin are the Proteins in Muscle Tissue that enable movement
• Energy — Under conditions of Carbohydrate Deficiency, Proteins can be converted into Glucose (Gluconeogenesis)

Requirements and Sources

Daily protein requirements vary depending on age, sex, health status, and level of physical activity. The Italian Recommended Dietary Allowances (LARN) specify a reference intake of 0.9 g per kg of body weight per day for sedentary adults in good health. For athletes and sportspeople, requirements can rise to 1.4–2.0 g/kg/day depending on the type and intensity of training.

The richest dietary sources include lean meats, fish, eggs, dairy products, legumes, and whole grains. From a dietary supplement perspective, the most commonly used forms are:

• Whey Protein — High biological value and rapid absorption; ideal for post-workout use
• Casein — Slow digestion, sustained release of Amino Acids; recommended for nighttime consumption
• Soy Protein — a complete plant-based source, a popular choice in Plant-Based formulations
• Pea and Rice Proteins — When combined, they provide a complete Amino Acid profile; widely used in the Vegan Sports Nutrition segment
• Egg Protein — one of the highest biological values available; intermediate digestion

EFSA Claims approved

EFSA has approved several nutrition and health claims related to protein, including:

• Protein helps build and maintain muscle mass
• Protein helps maintain normal bones
• Protein helps maintain normal hair and nails

Excessive and prolonged protein intake — particularly more than 2 g/kg/day without a medical indication — can overload kidney function in individuals with a predisposition or preexisting conditions. In cases of kidney or liver failure, a doctor’s advice is required before increasing protein intake with supplements. During pregnancy and breastfeeding, significant changes to the nutritional profile always require professional supervision.

We always remind you that it is important to consult a healthcare professional before starting any new supplement or treatment.