FOOD AND NUTRITION

Grade 8, Year 2011-2012

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, galactoseDisaccharides: 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

Name Group Source Diseases and symptoms caused by lack of vitamin

Vitamin A Fat soluble Liver, cheese, butter, margarine, milk, eggs, dark green and orange vegetables and fruits

Reduced resistance to disease, poor night vision

Vitamin C

Water soluble

Oranges, lemons, tomatoes, grapefruits, fresh green vegetables

Scurvy: Symptoms-Bleeding gums, poor healing of wounds

Vitamin D

Fat soluble Butter, milk, cheese, egg yolk, liver, fish liver oil

Calcium is not deposited properly in the bones

Vitamin B1

Water soluble

Cereals, peas, and beans

Beriberi

Vitamin K Fat soluble Green vegetables, also made by colon bacteria

Defective blood clotting

Mineral Salts

Mineral Salts

Roles Source

Iron Part 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

Iodine Needed 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

Phosphorus

Needed 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?