Macronutrients Microlecture Notes

Nutrients

  • Substances in food and water used for:
    • Energy
    • Growth and repair
    • Chemical reactions

Macronutrients

  • Essential nutrients needed in large amounts.
    • Carbohydrates
    • Lipids (fats)
    • Protein

Carbohydrates

  • Primary energy source, broken down into glucose.
  • 17kJ/gram
  • Prevents ketosis and provides fiber.
  • Used in DNA, RNA, and ATP production.
  • Excess stored as glycogen or fat.

Lipids (Fats)

  • Major source of stored energy: 38kJ/g
  • Forms cholesterol, steroid hormones, cell membranes, and bile.
  • Phospholipids for cell membranes.

Protein

  • Structural material (e.g., collagen, keratin).
  • Roles:
    • Structural, enzymes, hormones, carrier molecules, hemoglobin, contractile proteins, antibodies, energy.
  • RDI:
    • Men: 0.84g/kg/day
    • Women: 0.75g/kg/day
  • Essential Amino Acids: Histidine, Arginine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine
  • Hormones: Oxytocin, Prolactin, Insulin, Glucagon, Thyroxine, Calcitonin, Parathyroid hormone, Antidiuretic hormone

Protein Turnover

  • Continuous process creating an amino acid pool.
  • Degradation rate varies.
  • Amino acids used for nitrogen compounds or nitrogen is extracted for other uses.

Protein:Nitrogen Balance

  • Protein:Nitrogen balance = Nitrogen intake - Nitrogen output
  • Positive Balance: Nitrogen intake > Nitrogen output then > 0
  • Negative Balance: Nitrogen intake < Nitrogen output then < 0