nutrients in human notes

• Food substances essential to health

  • Carbohydrates
  • Protein
  • Lipids
• Primary food substances


  Keep us alive
• Water, carbohydrates, lipids, protein

  Provide energy
• Protective food substances


  Need small amount to keep us healthy
• Protective food substances


  • Dietary fibre
  • Minerals
  • Vitamins
• Carbohydrates


  Carbon, hydrogen in 2:1 ratio, oxygen
• Carbohydrate groups


  • Monosaccharides (simple sugars, small size pass through cell membrane)
  • Disaccharides
  • Polysaccharides
• Monosaccharides


  • Glucose
  • Fructose
  • Galactose
• Disaccharides


  • Maltose
  • Sucrose
  • Lactose
• Polysaccharides


  • Glycogen
  • Starch
  • Cellulose
• Monosaccharides + disaccharides


  Sweet, soluble in water
• Disaccharides + polysaccharides


  Join together by condensation, break down by hydrolysis
• Uses of carbohydrates


  Main source of energy, energy reserve
• Carbohydrate tests


  • Glucose test paper (change colour)
  • Iodine test for starch (brown to blue-black)
  • Benedict's test for reducing sugars (brick red precipitate)
• Protein


  Carbon, oxygen, sulphur, hydrogen, nitrogen as basic elements. Amino acids as basic units.
• Amino acids


  Contain amino group, carboxyl group, side chain
• Protein structure


  1. Dipeptide

  2. Polypeptide

  3. Unique sequence determines final shape and function
• Essential amino acids


  Cannot be produced by body, must be obtained from food
• Non-essential amino acids


  Can be produced by body
• Protein functions


  Repair and growth of body tissue, energy source (last)
• Protein deficiency (Kwashiorkor)


  Poor growth, weak muscles, swollen abdomen
• Lipids


  Carbon, hydrogen in 2:1 ratio, oxygen. Insoluble in water, soluble in organic solvents.
• Triglycerides


  One glycerol + 3 fatty acids, formed by condensation, broken down by hydrolysis
• Triglycerides


  • Solid at room temp (fats from animals)
  • Liquid at room temp (oils from plants)
• Lipid functions


  Energy reserve, shock absorber, heat insulator, absorption and transport of lipid-soluble vitamins, production of hormones, component of cell membrane
• Lipid test


  Grease spot test
• Minerals


  Inorganic food substances needed in small amounts, no energy value, regulate metabolic reactions, building body tissue
• Major minerals


  • Calcium
  • Iron
  • Sodium
  • Iodine
  • Potassium
  • Phosphorus
• Calcium functions


  Component of bones and teeth, involved in blood clotting, muscle contraction, sending messages in nervous system
• Calcium deficiency


  Rickets in children, osteoporosis
• Calcium sources


  Dairy products, canned sardines, leafy greens
• Iron functions


  Component of haemoglobin in red blood cells
• Iron sources


  Beef, liver, beans, leafy greens
• Vitamins


  Organic food substances needed in small amounts, no energy value, regulate metabolic reactions
• Vitamin types


  • Lipid-soluble (A, D, E, K)
  • Water-soluble (B, C)
• Lipid-soluble vitamins


  Absorbed with lipids, stored in large amounts, can be harmful in excess
• Water-soluble vitamins


  Can't be stored in large amounts, excess excreted, important to take regularly
• Vitamin A functions


  Formation of pigment in retina, keep cornea, skin, lining of alimentary and breathing system healthy
• Vitamin A deficiency


  Night blindness, drying up of cornea and skin, easy infection
• Vitamin A sources


  Fish liver oil, liver, eggs, dairy, vegetables and fruits with orange/yellow pigments