1Chap 6 protein 24

Chapter 6: Dietary Protein

FN 2070

Overview

• This chapter covers various aspects of dietary proteins, including their functions, requirements, and sources, as well as protein metabolism, synthesis, and nutrition.

Key Topics

• Functions of protein

• Protein requirements

• Complete vs. incomplete proteins

• Vegetarian protein nutrition

• Protein structure

• Protein synthesis

• Digestion and absorption

• Amino acid pool

• Protein balance

• Malnutrition related to protein

• Popular topics: Protein powders, BCAAs, collagen supplements, protein for sports

What is Protein?

• Definition: Collection of amino acids required for the structure and function of body tissues.

• Peptide Bonds: Join amino acids to form proteins.

Importance of Protein

• Essential Component: Vital for body tissues, hormones, enzymes.

• Functionality: Supports growth, repair, and can provide energy.

• Transport: Helps transport oxygen and other critical substances in the body.

Protein Structure

• Amino Acids: Building blocks of proteins.

• Types of Proteins:

  • Peptides: Short chains of amino acids.

  • Proteins: Longer chains functioning in various roles in the body.

Functions of Protein

1. Transport: Carry compounds through fluids and across cell membranes.

2. Enzymes: Catalyze reactions for efficiency and speed; form new compounds or split existing ones.

3. Fluid Balance: Regulate fluid levels in bodies by attracting fluids in blood vessels.

   • Edema: Caused by protein deficiencies leading to fluid leakage into interstitial spaces.

4. Acid/Base Balance: Maintain pH levels as amphoteric substances.

5. Immunity: Antibodies fight specific invaders; antigens trigger antibody production.

6. Hormones: Regulate biological processes, e.g., muscle growth, hunger, heart rate.

7. Energy: Utilized when carbohydrate and fat sources are low; least desirable energy source (4 kcal/gram).

Protein Requirements by Age

• Sedentary Adults: 0.8 g/kg of body weight.

• Children and Adolescents: Higher requirements during growth phases.

• Pregnant/Lactating Women: Increased protein needs to support fetal growth and lactation.

• Athletes:

  • Endurance athletes: 1.2 to 1.4 g/kg/day.

  • Strength training: 1.6 to 2.0 g/kg/day.

Protein Sources

• Animal Proteins: Meat, poultry, fish, dairy, eggs.

• Plant Proteins: Beans, legumes, nuts, seeds, whole grains, tofu, tempeh.

Complete vs. Incomplete Proteins

• Complete Proteins: Provide all essential amino acids (e.g., animal proteins, soy).

• Incomplete Proteins: Lack one or more essential amino acids (e.g., most plant proteins).

Protein Digestion and Absorption

• Mouth: Chewing begins mechanical breakdown.

• Stomach: Hydrochloric acid and pepsin denature proteins and start digestion.

• Small Intestine: Further breakdown by enzymes from the pancreas; absorption into the bloodstream.

• Transport: Utilizes active transport mechanisms.

Amino Acid Pool

• Constant turnover of proteins with amino acids being recycled within the body.

• Deamination: Removal of the amine group for energy use.

• Glucose Production: Amino acids can be converted to glucose if needed.

Protein-Related Malnutrition

• Kwashiorkor: Result of insufficient protein intake despite adequate calories.

• Marasmus: Total nutritional inadequacy, leading to muscle wasting.

Protein Powders

• Usage: Appetite control, weight management, muscle mass increase.

• Types: Soy, casein, egg, and pea protein, with varying absorption rates and dietary compatibility.

• Certification: Look for NSF-certified protein powders for safety and quality assurance.

Wrap Up: Key Takeaways

• Understand the importance of protein structure, functions, digestion, absorption, nutritional requirements, and implications of deficiencies.