A diet may consist of the right kind of food, in the right proportion but it will still be unsatisfactory if the food is not clean and pure. Food-stuffs, may be exposed to dust, dirt, flies, cockroaches and rats which infect it with diseased germs, which are taken into food canal, when the food is eaten. The diseases typhoid, dysentery, cholera and tuberculosis, may be carried by dirty food, dirty fingers, dirty flies, water and milk.

• Water is usually purified and filtered. The best source is to boil drinking water, at boiling point for at least 20 minutes. Allow to cool and strain.
• Milk is a valuable food-stuff, but is readily infected with germs, from the cow or from dirty methods of handling. Milk can be purified by boiling for a short time. Boiling for a long time lowers the food value and destroys the vitamins.
• Meat and fish should be fresh and not exposed to dust, dirt or insects. Fruit and vegetables should always be thoroughly washed before eating. Fruits with damaged or broken skins should not be used. When eating raw vegetables be careful to wash thoroughly, if required a little potassium permanganate can be used. Cooked vegetables, however are quite safe.
• Another important result of cooking food is that the high temperature kills diseased germs which may be present in the raw food. Cooking makes meat and fish more attractive and digestible. Cooked meat will last longer than uncooked meat. Fish decays quickly and should always be cooked as soon as possible. She’ll fish decomposes quickly almost immediately and very often carry disease, so they should be bought alive and should be cooked very thoroughly.