Nutrition

• Balanced diet


  Includes an adequate amount of nutrients needed to maintain good health

  
• Main groups of nutrients in a balanced diet

  • Carbohydrates
  • Fats (lipids)
  • Proteins
  • Vitamins
  • Minerals
• Water


  Not considered a nutrient but essential component of a balanced diet

  
• Dietary fibre


  Not considered a nutrient but essential component of a balanced diet

  
• A balanced diet provides energy for the growth and repair of all cells and the proper functioning of all our vital organs

  
• Carbohydrates


  Organic molecules made up of carbon, hydrogen and oxygen
• Main groups of carbohydrates

  • Monosaccharides
  • Disaccharides
  • Polysaccharides

  
• Monosaccharides


  Simplest carbohydrates, made up of only one sugar molecule
• Disaccharides


  Formed when two monosaccharides are combined

  
• Polysaccharides


  Consist of many monosaccharide molecules joined together in a condensation reaction

  
• Carbohydrates


  • Source of energy
  • Storage of energy
  • Source of dietary fibre

  
• Foods containing carbohydrates


  • Sugars
  • Starches

  
• Fats


  Organic molecules made up of carbon, hydrogen and oxygen
• Lipids


  Group that includes fats, triglycerides, phospholipids, waxes, steroids and cholesterol
• Fats vs oils


  Fats are solid at room temperature, oils are liquid at room temperature
• Fat molecules


  Made up of glycerol and fatty acids

  
• Functions of fats


  • Alternative source and store of energy
  • Essential component of cell membranes
  • Solvent for synthesis, transport and absorption of some vitamins and hormones
  • Insulating material to reduce loss of body heat
• Most of the fatty acids required in our diet can be synthesised by our bodies
• Saturated fats found in animals are unhealthy and may cause coronary heart disease
• Unsaturated fats found in nuts, vegetable oils and fish are healthier
• Proteins


  Organic molecules of long chains of amino acids made up of carbon, hydrogen, oxygen and nitrogen
• Green plants can manufacture all the amino acids they need on their own, but humans and other animals need to obtain 8 essential amino acids from their food
• Amino acids


  Link together in a condensation reaction to form long chains called polypeptides
• Peptide bond


  Bond formed between amino acids
• Proteins


  Formed when polypeptides link together and fold into specific 3D shapes
• Functions of proteins


  • Provide amino acids for synthesis of new proteins for growth and repair
  • Provide amino acids for synthesis of enzymes, hormones and antibodies
• Foods rich in proteins


  • Meat, seafood, eggs, milk, beans, nuts, grains, vegetables
• Kwashiorkor and marasmus


  Deficiency diseases caused by lack of proteins in the diet, especially in growing children
• Water


  Molecule made up of 2 hydrogen atoms and 1 oxygen atom
• Functions of water


  • For metabolism
  • As a solvent
  • For transport
  • Key component of protoplasm, lubricants, digestive juices, blood and tissue fluid
  • Control of body temperature
• Vitamins


  Organic substances required by the body in small amounts to ensure normal growth and metabolism
• Minerals


  Inorganic substances needed in small amounts for proper functioning of the body
• Lack of any vitamin or mineral will result in a deficiency disease
• Importance of vitamins A and C

  • Vitamin A: For healthy vision, skin and immune system
  • Vitamin C: For healthy skin, bones, teeth and immune system
• Importance of calcium and iron

  • Calcium: For healthy bones and teeth
  • Iron: For healthy blood and energy production
• Health problems may also occur when excess vitamins or minerals are consumed
• Basal metabolic rate (BMR)


  Energy used for breathing, pumping heart, maintaining body temperature and chemical reactions to keep us alive
• BMR is higher in males than females, in those with larger body mass, and in infants and young children. BMR decreases with age and falls slightly in very hot climate
• Dietary requirements


  • Infants and young children: Higher energy and nutrient needs for growth
  • Adolescents: Higher energy and nutrient needs for growth spurt
  • Adults: Lower energy needs, focus on balanced diet
  • Elderly: Lower energy needs, focus on nutrient-dense foods
• Malnutrition


  Result of too much (over-nutrition) or too little (under-nutrition) of one or more nutrients