CIE IGCSE Biology: 复习笔记：7.1.1 Diet & Deficiencies

• A balanced diet consists of all of the food groups in the correct proportions
• The necessary food groups are:
  • Carbohydrates
  • Proteins
  • Lipids
  • Vitamins
  • Minerals
  • Dietary Fibre
  • Water

Food Groups Table

Vitamin and Mineral Requirements Table

Varying Dietary Needs of Individuals Table

Scurvy

• Scurvy is the name for a severe vitamin C deficiency
  • It is caused by a lack of vitamin C in the diet for over 3 months
• Its symptoms include:
  • Anemia
  • Exhaustion
  • Spontaneous bleeding
  • Pain in the limbs
  • Swelling
  • Gum ulcerations
  • Tooth loss
• It is a condition that was commonly seen in sailors between the 15th to 18th centuries
  • Long sea voyages made it very hard to access a ready supply of fresh produce
• Scurvy can be treated with oral or intravenous vitamin C supplements

Rickets

• Rickets is a condition in children characterised by poor bone development
• Symtpoms include:
  • Bone pain
  • Lack of bone growth
  • Soft, weak bones (sometimes causing deformities)
• Rickets is caused by a severe lack of vitamin D
  • Vitamin D is required for the absorption of calcium into the body
    • Calcium is a key component of bones and teeth
• Vitamin D mostly comes from exposure to sunlight but it can also be found in some foods (fish, eggs and butter)
• The treatment for rickets is to increase consumption of foods containing calcium and vitamin D
  • Alternatively vitamin D supplements can be prescribed