Nutrition Basics and Metabolism Notes

Nutrition Basics

  • Macronutrients vs Micronutrients
    • Macronutrients:
    • Large components of diet.
    • Include carbohydrates, lipids (fats), and proteins.
    • Micronutrients:
    • Small components needed in lesser amounts.
    • Include vitamins and minerals, along with water.

Definitions

  • Diet: Refers to what people eat, not restricted intake.
  • Percentage Guidelines:
    • Essential for health, with variations for specific health conditions.
  • MyPlate:
    • Visual model for balanced diet, suggesting half the plate be fruits and vegetables
    • Other half should include grains and proteins.

Macronutrients

  • Carbohydrates:

    • 45-65% of daily intake, primary energy source.
    • Types:
    • Monosaccharides (e.g., glucose).
    • Disaccharides (e.g., sucrose).
    • Polysaccharides (e.g., starches, fibers).
    • Functions: Energy production, brain function, excess converted to fat.

  • Lipids/Fats:

    • 20-35% of daily intake, higher energy density (9 kcal/g).
    • Types:
    • Saturated fats (found in animal products).
    • Unsaturated fats (found in fish, nuts, and vegetable oils).
    • Functions: Energy storage, insulation, cellular structure,
    • Essential fatty acids include omega-3 and omega-6, cannot be synthesized by the body.

  • Proteins:

    • 12-20% of daily intake, essential for muscle and tissue repair.
    • Complete proteins contain all essential amino acids (e.g., eggs, meat).
    • Incomplete proteins lack some amino acids, can be combined for complete sources (e.g., rice and beans).
    • Functions: Structural role, regulatory enzymes and hormones, essential for growth.

Micronutrients

  • Vitamins:
    • Water-soluble: B-complex and Vitamin C; can be excreted easily.
    • Fat-soluble: Vitamins A, D, E, K; can accumulate to toxic levels.
    • Roles include coenzymes, antioxidant functionalities, support energy production.
  • Minerals:
    • Major minerals: calcium, potassium, magnesium, sodium, phosphorus.
    • Trace minerals: iron, iodine, etc.
    • Functions include supporting structural components in bones, and participation in metabolic processes.

Metabolism Overview

  • Metabolism: Combination of anabolism (building up) and catabolism (breaking down).
  • Stages of Metabolism:
    • Stage 1: Digestion and absorption in GI tract.
    • Stage 2: Metabolism within the cell's cytoplasm.
    • Stage 3: Energy production in mitochondria (ATP synthesis).
  • Cellular Respiration:
    • Involves glycolysis, citric acid cycle (Krebs cycle), and oxidative phosphorylation.
    • Glycolysis: Extracts energy from glucose, produces pyruvic acid and a net gain of 2 ATP.
    • Citric Acid Cycle: Converts pyruvic acid into CO2, produces more ATP along with NADH and FADH2.
    • Oxidative Phosphorylation: Utilizes electron transport chain to produce ATP, depends on proton gradient across mitochondrial membrane.

Important Concepts in Digestion

  • Energy Yield:
    • Glucose yields highest ATP when metabolized.
  • Insulin's Role: Assists glucose entry into cells.
  • Essential Nutrients: Approximately 40 essential nutrients must be derived from the diet.

Takeaway Points for Health

  • Focus on a balanced diet rich in fruits, vegetables, whole grains, and varied protein sources.
  • Understand macronutrient contributions to energy and health, and the importance of micronutrients in physiological functions.
  • Adjust dietary intake based on individual health needs and conditions, recognizing evolving nutritional guidelines and research.