FOOD AND NUTRITION Grade 8, Year

What is nutrition?  Nutrition is the obtaining of food to provide energy and substances needed for growth and repair.

Nutrients  Nutrient is all useful substances needed by living organisms.  There are 7 different nutrients needed for a balanced diet for humans: Carbohydrates, proteins, fats, vitamins, minerals, fibre and water.

Carbohydrates Elements of carbohydrates: Carbon (C), Hydrogen (H) and Oxygen (O). Includes sugars and starches. Sugars: Monosaccharide: glucose, fructose, galactose Disaccharides: Maltose, Sucrose, Lactose Starches: Polysaccharides: Starch, Glycogen and Cellulose

Where can we get carbohydrates?  Starch: potatoes, bread, rice and other cereals.  Sugar : Sucrose (table sugar) - drinks, jam Glucose and fructose – fruits and vegetables

Proteins  Elements of proteins: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N) and sometimes Sulfur (S).  Protein molecules consist of long chains of amino acids  Proteins provide the chemical substances needed to build cells and tissues  Animal Protein: meat, fish, eggs, milk, cheese  Plant protein: wheat and maize

Fats/Lipids  Elements of fats: Carbon (C), Hydrogen (H) and Oxygen (O).  Fatty acids and glycerol will form fats.  Animal fats: meat, milk, cheese, butter and egg yolk  Plant fats: palm oil, sunflower seed oil  Fats are useful as long-term storage of energy, to form part of the cell membrane, insulate body temperature

Vitamins  They are not broken down for energy  They are essential in small quantities for health  Vitamins are sometimes grouped into fat soluble and water soluble

NameGroupSourceDiseases and symptoms caused by lack of vitamin Vitamin AFat solubleLiver, cheese, butter, margarine, milk, eggs, dark green and orange vegetables and fruits Reduced resistance to disease, poor night vision Vitamin CWater solubleOranges, lemons, tomatoes, grapefruits, fresh green vegetables Scurvy: Symptoms-Bleeding gums, poor healing of wounds Vitamin DFat solubleButter, milk, cheese, egg yolk, liver, fish liver oil Calcium is not deposited properly in the bones Vitamin B 1 Water solubleCereals, peas, and beansBeriberi Vitamin KFat solubleGreen vegetables, also made by colon bacteria Defective blood clotting

Mineral Salts RolesSource IronPart of haemoglobin molecule and takes important part in carrying oxygen liver, eggs, groundnuts, bread, spinach Calcium Deposited in the bones and the teeth and makes them hard Present in blood plasma and plays an essential part in normal blood clotting Milk, cheese IodineNeeded in small quantities. It forms an essential part of the molecule of thyroxine (hormone produced by thyroid gland) Sea fish, also present in most vegetables PhosphorusNeeded for calcium phosphate of bone and also for DNA Cheese, meat, fish

Water and Fiber (Roughage)  Water acts as a solvent and as a transport medium for digested food, salts, vitamins, and excretory products (excess salt and urea).  Fiber can be found in plants. The cell wall of plants consist of cellulose which is a carbohydrate that can’t be digested in our body since we don’t have enzyme that is responsible for that. Therefore, cellulose will go directly to our large intestine and will be digested by bacteria that live in it. Then, it will also help the movement of waste through the digestive tracts.

Questions  List the components of a balanced diet for a human  Give one example of each of the following: a simple sugar, a complex (double) sugar, a complex carbohydrates.  Which elements are present in protein, but are not found in carbohydrates and fats?  Name the small molecules that are joined together to make protein molecules?