Carbohydrate

• Includes: Grains in bread and pasta, Table sugar, Fibre in fruit and vegetables
• Functions:

  • Substrates for energy metabolism
  • Play a role in satiety, blood glucose control, lipid metabolism
• When fermented in the gut by bacteria (e.g. Soluble fibre, Oligosaccharides)

  • Regulate metabolism and balance of commensal flora (Soluble fibre)
  • Health of large bowel mucosa
• International recommendations:

  • Diet contains at least 400 g/ 5 fruits & vegetables a day (Excluding potato, sweet potato, cassava, other starchy roots)
• Carb composed of: Carbon, Hydrogen, Oxygen

  • Bond together to form sugar/ saccharide units
  • No. of these units + How they are joined = Properties
• 3 Groups:

  • Simple carbohydrates (1 - 2)
  • Oligosaccharides (3 - 9)
  • Polysaccharides (> 10)
• Glucose

  • Simplest sugar unit (Monosaccharide)
  • Most abundant
  • Used as a source of energy by EVERY cell in the body
• • Others: Fructose, Galactose (2-unit sugar; held tgt by a glycosidic bond); Found naturally in fruits; milk, milk products
  • Also found in processed & refined sugar (e.g. Candy, Table sugar, Syrups, Soft drinks)
  • Most simple sugar occurring in nature = Disaccharides
• Oligosaccharides

  • 3 - 8 basic sugar units w/ tight bonding
  • Found in: Beans, Lentils, Onions, Garlic, Artichokes
• Oligosaccharides

  • not digested in the small intestine --> Fermented by resident colonic bacteria
  • Are Indigestible carbohydrate = Prebiotics
  • Functions:

  1. Modulate the composition and/ or activity of the gut bacteria
  2. Beneficial physiological effect on the host
• Oligosaccharides

  • Raffinose (Trisaccharide)
  • Starchyose (Tetrasaccharide)