Human nutrition

• Principal sources and dietary importance of

  • Carbohydrates
  • Lipids
  • Proteins
  • Vitamin C
  • Vitamin D
  • Calcium
  • Iron
  • Fiber
  • Water
• Carbohydrates


  • Found in starch and sugar
  • Good quality carbohydrates: sweet potato, oatmeal, beans, whole wheat pasta, cereal, fruit, quinoa, lentil, squash, brown/wild rice, whole grain bread
• Carbohydrates (in biochemistry)


  • Synonymous with saccharide, meaning sugar
  • Can be complex carbohydrates like starch or simple carbohydrates like sugar
• Carbohydrates


  • Composed of carbon and water (one carbon, two hydrogen, one oxygen)
  • Provide energy for the body
  • Prevent breakdown of proteins for energy
  • Facilitate fat metabolism
  • Can form ketones if diet is low in carbohydrates
• Foods rich in proteins


  • Meat (turkey, eggs, fish)
  • Meatless proteins (peanut butter, almonds, pumpkin seeds, cheese, Greek yogurt, chia seeds, oats, flax seeds, cottage cheese)
• Proteins


  • Act as enzymes that catalyze biochemical reactions
  • Used as transport molecules like hemoglobin
  • Used for storage like ferritin
  • Major components of muscles, skin, and bones
  • Mediate cell response
• Foods rich in fats

  • Animal fats (butter, cream, lard, meat fat)
  • Plant fats (corn oil, olive oil, peanut butter, almond oil)
• Fats and oils


  • Carry fat soluble vitamins A, D, E, K
  • Concentrated source of energy (9 calories per gram)
  • Add flavor and satisfy hunger
  • Protect internal organs and insulate the body
  • Required for new cell membranes
• Vitamin C


  Present in citrus fruits, required for healthy gums and immune system
• Vitamin D


  Fat soluble vitamin, present in dairy, required for absorption and deposition of calcium
• Calcium


  Present in milk and dairy, required for strong bones and teeth
• Iron


  Present in red meat and liver, required for hemoglobin which transports oxygen
• Fiber


  • Obtained from fruits, vegetables, whole grains
  • Cannot be digested, adds bulk to feces and prevents constipation and colon cancer
• Sources of water


  • Food (e.g. apples)
  • Drinks (e.g. juices)
  • Metabolic water from respiration
• Uses of water


  • Plasma, tissue fluid, urine, feces, exhaled air
  • Medium for enzyme reactions and hormone transport
  • Lubricates eyes
• Diseases in the syllabus

  • Scurvy
  • Rickets
  • Anemia
• Scurvy


  Caused by vitamin C deficiency, results in bleeding gums and delayed wound healing
• Rickets


  Caused by lack of calcium and vitamin D, results in soft bones and bowed legs in infants
• Anemia


  Caused by lack of iron, results in pale skin, fatigue, and breathlessness
• Components of a balanced diet

  • Carbohydrates
  • Fats
  • Proteins
  • Vitamins
  • Mineral salts
  • Water
  • Fiber
• Carbohydrates, fats, and proteins need to be digested, while vitamins, mineral salts, and water are absorbed without digestion. Fiber is not digested and is passed out.
• Main regions of the digestive system

  • Mouth
  • Salivary glands
  • Esophagus
  • Stomach
  • Small intestine
  • Large intestine
  • Pancreas
  • Liver
  • Gallbladder
• Most foods must be digested before they can be absorbed.
• Physical digestion


  1. Chewing

  2. Increasing surface area
• Chemical digestion


  Enzyme action
• Physical digestion increases the surface area of food for the action of enzymes.
• Types of human teeth

  • Incisors
  • Canines
  • Premolars
  • Molars
• Structure of human teeth

  • Crown
  • Root
  • Enamel
  • Dentin
  • Pulp
• Functions of human teeth

  • Incisors: Cutting
  • Canines: Tearing
  • Premolars: Grinding
  • Molars: Grinding
• Main regions of the digestive system

  • Mouth
  • Esophagus
  • Stomach
  • Small intestine
  • Large intestine
  • Pancreas
  • Liver
  • Gallbladder
• Most foods must be digested before they can be absorbed
• Physical digestion


  Breaking down food into smaller pieces
• Chemical digestion


  Using enzymes to break down food molecules
• Physical digestion increases the surface area of food for the action of enzymes
• Types of human teeth

  • Incisors
  • Canines
  • Premolars
  • Molars
• Structure of human teeth

  • Crown
  • Root
  • Enamel
  • Dentin
  • Pulp cavity
• Function of human teeth

  • Incisors and canines for biting
  • Premolars and molars for grinding and crushing
• Enzymes are needed for chemical digestion to break down food molecules
• Increasing surface area of food

  Allows enzymes to digest food more efficiently
• Digestion and absorption of food occurs in the small intestine