Nutrition-Basic concept

• Nutrition


  The science of food and its relation to health
• Food


  • Supplies nutrients
  • Health is dependent on a balanced supply of nutrients
• Classes of Nutrients

  • Carbohydrates
  • Lipids (fats)
  • Proteins
  • Vitamins
  • Minerals
  • Water

  
• Organic nutrients


  Contains carbon
• Inorganic nutrients


  Does not contain carbon
• Essential nutrients


  Nutrients the body either cannot make or cannot make enough of to meet its needs, must be obtained from foods
• Nonessential nutrients


  Body can make from other nutrients ingested
• Macronutrients


  Need in relatively large amounts
• Micronutrients


  Need in relatively small amounts
• Energy-yielding nutrients

  • Carbohydrates
  • Fats (lipids)
  • Proteins

  
• Kilocalorie


  A measure of energy, what most think of as a "calorie"

  
• The body uses the energy yielding nutrients to fuel all activities
• If more energy is ingested than is needed to fuel body activities the extra energy is stored as fat
• Dietary Carbohydrates


  • Sugar
  • Starches
  • Fibre
• Monosaccharides


  Glucose, fructose and galactose
• Disaccharides


  Sucrose, lactose and maltose
• Polysaccharides


  • Starch - long chains of glucose found in plants
  • Fiber - mostly indigestible CHO
• Carbohydrates


  • Body's primary source of energy
  • Use as glucose
  • Brain's only source of energy
  • Stores are limited (~12-24 hours in liver and muscle as glycogen)
  • In plants as starch

  
• Insoluble fiber


  Non-viscous; cellulose, lignins
• Soluble fiber


  Viscous & fermentable; pectins, gums, mucilages
• Lipids


  A diverse group of biomolecules which share the property of being insoluble in water
• Main classes of lipids

  • Oils and fats
  • Waxes
  • Phospholipids
  • Sterols
• Fats & Oils

  Esters of glycerol with higher fatty acids, also called glycerides
• Vegetable oils

  Extracted from seeds
• Vegetable fats

  Extracted from coconut
• Animal oils


  e.g. Cod liver oil, whale oil

  
• Animal fats


  Lard and butter
• Physical properties of fats & oils

  • Colorless liquid or solid, but maybe yellow or brown due to impurities
  • Lighter than water and immiscible with it
  • Soluble in organic solvents
  • Non-volatile
  • Upon heating they decompose to give an irritating odor
  • Form emulsions in the presence of detergents/surfactants
• Uses of fats & oils

  • Food material
  • Manufacture of glycerol, fatty acids, soaps, candles, vegetable ghee, margarine, hair oils, etc.
  • Paints, varnish, etc.
  • Purgative, source of vitamins A and D, medicine
  • Illuminants and lubricants

  
• Waxes

  Mixtures of esters of higher fatty acids, used as a car wax and in floor polishes
• Waxes in living organisms

  • Leaves - protectant against parasites and minimizes water evaporation
  • Feathers of birds - water repellent
• Phospholipids


  Like a triglyceride in structure, has a phosphate group attached and choline or another nitrogen containing compound in place of one of the fatty acids, partially hydrophobic and partially hydrophilic
• Sterols


  Large complex molecules consisting of interconnected rings of carbon, include cholesterol and vitamin D
• Fats


  • Essential in small amounts, key regulators
• Types and sources of fats

  • Saturated fat
  • Monounsaturated fat
  • Polyunsaturated fat
  • Trans fat
• Fats and health

  • Affect blood cholesterol levels, triglyceride levels, inflammation, heart rhythm, blood pressure, and cancer risk
  • Best choices are monounsaturated fats and polyunsaturated omega-3 fats
  • Limit intake of saturated and trans fats
• Functions of lipids in the body

  • Concentrated source of energy
  • Adipose tissue - protects organs, regulates temperature
  • Cell membrane structure - forms part of cell membrane, helps transport nutrients
• Proteins


  The largest and most complex molecules known, the main functional component of the body
• Categories of proteins

  • Structural (e.g. muscle, connective tissue)
  • Functional (e.g. enzymes)
• Amino acids

  Nonessential, essential, conditionally essential