BIOL217 - Week 6

BIOL217: Nutrition

WEEK 6: PROTEINS AND AMINO ACIDS

Understanding Protein

  • Definition: The term "protein" refers to both the macronutrient and the molecules composed of amino acids.

  • Macronutrient: Proteins are one of three macronutrients that can provide energy.

  • Molecules: Proteins are complex molecules made up of long chains of amino acids, crucial for various bodily functions.

Functions of Proteins

  1. Building and Repairing Tissues: Essential for growth and recovery.

  2. Enzymatic Activity: Functions as enzymes catalyzing chemical reactions.

  3. Hormones and Antibodies: Acts as hormones regulating physiological processes and antibodies defending against pathogens.

  4. Dietary Source: While dietary intake is vital, the body can perform protein synthesis to create proteins as needed.

Amino Acids and Proteins

  • Core Structure: Each amino acid contains:

    • A central carbon atom.

    • A hydrogen atom.

    • An amino group (-NH2).

    • A carboxyl group (-COOH).

    • A variable side chain (R group) that differs across amino acids.

  • Building Blocks: Often referred to as the building blocks of proteins, analogous to how monosaccharides are to carbohydrates.

Types of Amino Acids

  1. Essential Amino Acids: Nine amino acids that cannot be synthesized by the body and must be sourced from diet.

  2. Nonessential Amino Acids: Amino acids that the body can produce in sufficient amounts but are still important for various bodily functions.

    • These can be synthesized from other amino acids, carbohydrates, or fats.

List of Amino Acids

  • Essential: Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine.

  • Nonessential: Alanine, Arginine*, Asparagine, Aspartic acid, Cysteine*, Glutamic acid, Glutamine*, Glycine*, Proline*, Serine*, Tyrosine*. *Conditionally essential under specific circumstances.

Amino Acid Pool

  • Definition: Refers to the reserve of amino acids found in tissues and fluids available for body use.

  • Protein Turnover: Ongoing process involving the synthesis and degradation of proteins, balancing body protein levels.

Classification of Proteins

Complete and Incomplete Proteins

  • Complete Proteins: Contain all nine essential amino acids. Common sources include meat, fish, eggs, and dairy.

  • Incomplete Proteins: Lacking one or more essential amino acids, typically found in plant-based foods such as legumes, grains, nuts, and seeds.

    • Combining different incomplete proteins can form a complete protein (e.g., beans and rice).

Consequences of Missing Essential Amino Acids

  • Impaired Growth: Essential for development, particularly in children.

  • Muscle Wasting: Lack can lead to muscle loss.

  • Immune Deficiency: Essential for maintaining immune factors.

  • Poor Wound Healing: Amino acids play a significant role in tissue repair.

  • Fatigue and Weakness: Involved in energy production and metabolic processes.

Dietary Protein Sources

  • Protein Deficiency: Rare in Canada, with average intake around 17% of total kcalories.

  • Common Sources: Milk and dairy are primary protein sources, followed by meat. Fish, legumes, nuts, and seeds are less frequently consumed.

Nutritional Quality of Animal vs Plant Proteins

  • Animal Protein: Contains more easily absorbed nutrients such as B vitamins and minerals but is lower in fiber and can be higher in fat.

  • Plant Protein: Provides some B vitamins and minerals but may have lower bioavailability.

Protein Balancing and Health Implications

  1. Protein Requirements: Varies based on age, gender, and life stage; calculated through body weight.

  2. Protein Deficiency and Excess: Both conditions can result in significant health issues including muscle loss, lowered immune response, and risks for various diseases.

Weight Management and Body Composition

  • Obesity Statistics: Notable increases in adult and child obesity, leading to increased health risks and economic burdens estimated at $7.1 billion annually in Canada.

  • BMI Classification: Healthy range is defined for BMI (18.5 - 24.9); categories include overweight (25 - 29.9) and obese (>30).

Recommendations and Strategies

For Weight Loss and Muscle Gain

  • Nutritional Adjustments: Recommendations for high protein consumption to aid weight loss and maintain muscle mass during dieting.

  • Behavioral Modifications: Mindful eating, portion control, hydration, and increasing physical activity are key strategies for effective weight management.

Summary of Effective Dietary Practices

  1. Sustainability: Long-term dietary patterns should promote continuous health rather than rapid fixes.

  2. Behavioral Changes: Emphasizing a shift in lifestyle rather than temporary dietary restrictions can lead to better outcomes.

Conclusion

  • Week 9: Midterm examination covering all material to date, serving as a crucial assessment of understanding nutritional concepts and their implications for health.