Journey of Protein from Mouth to Muscle

Introduction

• Focus on how protein is broken down, absorbed, and utilized.
• Key Terms: Digestion vs Absorption.

Digestion vs. Absorption

• Digestion: Breaking down food into smaller molecules.
• Absorption: Smaller molecules entering the bloodstream.
• Different segments of the digestive tract specialize in either digestion or absorption.

Oral Cavity

• Mechanical digestion: Chewing.
• Chemical digestion: Enzymes from salivary glands.
• Some absorption here (e.g., sublingual medications).

Esophagus to Stomach

• Food travels down the esophagus to the stomach.
• Stomach features: Tunica mucosa, gastric rugae.
• Cells & Functions:
  • Mucous Cells: Secrete mucus to protect stomach.
  • Parietal Cells: Secrete hydrochloric acid (denatures proteins, kills pathogens).
  • Chief Cells: Secrete pepsinogen, converted to pepsin (breaks down proteins).
• Digestion in Stomach: Mechanical (churning) and chemical (enzymes and HCl).
• Creating Chyme: Mixture of stomach juices and food.

Pyloric Sphincter to Small Intestine

• Pyloric Sphincter: Regulates food passage to the small intestine.
• Small Intestine Segments:
  1. Duodenum: Receives bile (liver/gallbladder) and pancreatic enzymes.
  2. Jejunum: Major absorption site.
  3. Ileum: Additional absorption.
• Enzymes & Bile: Further breakdown of proteins and fats.
• Key absorption takes place in the small intestine.

Types of Protein: Amino Acids, Peptides, Proteins

• Amino Acids: Building blocks.
• Peptides: Chains of amino acids (dipeptides, tripeptides, polypeptides).
• Proteins: Folded polypeptides.

Absorption in the Small Intestine

• Increased Surface Area: Circular folds, microvilli for more absorption.
• Mesentery: Blood vessels absorb nutrients into the bloodstream.
• Amino acids absorbed into mucosal cells -> bloodstream -> liver.
• Liver's role: Monitors and distributes amino acids.

Protein Distribution & Utilization

• No control over where specific proteins go.
• Body absorbs amino acids and decides their utilization.
• Nitrogen Balance: Important for muscle growth.
  • Positive Balance: Intake > Loss -> Muscle building.
  • Negative Balance: Loss > Intake -> Muscle loss.
  • Goal is Positive Nitrogen Balance.

Does Protein Type Matter?

• Complete Proteins (Animal): Contain all essential amino acids (e.g., whey, casein).
• Incomplete Proteins (Plant): May lack some essential amino acids.
• Efficiency: Whey is absorbed quickly; plant proteins might need to be combined for completeness.

Importance of Protein Timing and Quantity

• Primary Goal: Eat enough protein over 24 hours.
• Secondary Goal: Optimize timing for quicker recovery (e.g., whey post-workout).

Recommendations

• Protein intake: 1.2-2g per kg of body weight, depending on goals.
• Balance protein intake, consider fast-digesting options post-workout for quicker recovery.

Summary

• Protein must be digested into amino acids before absorption and utilization.
• Nitrogen balance is key for muscle growth.
• Type and timing of protein can have secondary benefits once overall protein needs are met.

Additional Resources

• Detailed video on protein amount needed linked.
• Sponsor info: IR Restore device for hair growth.

Conclusion

• Understanding protein's journey helps optimize muscle growth and overall health.