Essential Role of Protein in Our Diet

Oct 2, 2024

Lecture on Protein in Human Diet

Importance of Protein

  • Protein is essential to the human diet.
  • Found in eggs, dairy, seafood, legumes, meats, nuts, and seeds.
  • Broken down and reformed into new proteins in our bodies to perform functions such as:
    • Fighting infections
    • Helping cells divide

Structure of Proteins

  • Protein is a chain of amino acids bonded by peptide bonds.
  • Chains twist and fold into final protein shapes.
  • When consumed, proteins are broken down into individual amino acids.

Amino Acids

  • Composition: Central carbon atom with an amino group, carboxylic acid group, hydrogen atom, and a unique side chain.
  • Exception: Proline, a ring structure.
  • Humans use about 20 amino acids:
    • Alanine, Arginine, Asparagine, Aspartic Acid, Cysteine, Glutamic Acid, Glutamine, Glycine, Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Proline, Serine, Threonine, Tryptophan, Tyrosine, Valine.
  • Classification:
    • Non-essential amino acids: Alanine, Asparagine, Aspartic Acid, Glutamic Acid, Serine (can be made by the body).
    • Conditionally essential amino acids: Arginine, Cysteine, Glutamine, Glycine, Proline, Tyrosine (produced under normal circumstances).
    • Essential amino acids: Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine (must be obtained from food).

Dietary Protein

  • Provides essential amino acids needed for own proteins and hormones.
  • Protein digestion (Proteolysis):
    • Begins in the stomach with hydrochloric acid and pepsin.
    • Continues in the duodenum with pancreatic enzymes.

Sources of Protein

  • Animal-based foods (eggs, dairy, seafood, meats) provide all essential amino acids.
  • Soy foods (plant-based) also provide all essential amino acids.
  • Plant foods have variable amino acid profiles; combinations like rice and beans can provide all essentials.
  • Comparable protein content in plant and animal foods (e.g., tofu vs. steak).

Daily Protein Requirements

  • Based on body weight: 0.8 g/kg.
  • Varies by age and gender:
    • Children (1-3 years): 13g
    • Ages 4-8: 19g
    • Ages 9-13: 34g
    • Females (14+): 46g
    • Males (14-18): 52g, (19+): 56g
  • Increased needs for pregnant/breastfeeding women, athletes, older adults.

Achieving Protein Intake

  • Multiple dietary options to meet requirements (e.g., Greek yogurt, tofu scramble).
  • Research ongoing on optimal protein amounts.

Health Considerations

  • Risk for protein deficiency in malnutrition, trauma, burn injuries, nutrient absorption issues.
  • Few health risks from high protein intake except in cases like kidney disease.

Summary

  • Protein is vital for bodily functions and varies in requirement based on life stage and health.
  • Both omnivorous and plant-based diets can meet protein needs through a variety of foods.