Citrus fruits such as oranges, grapefruit and lemons contain Vitamin C as well as tomatoes and green peppers (capsicums). Other vegetables providing an excellent source of Vitamin C include potatoes, peas, cabbage and cauliflower, snowpeas and spinach.

Vitamin C has a reputation for preventing colds and flu. Medical science suggests that it may reduce the symptoms or the duration of the cold but not prevent it.

A lack of Vitamin C has plagued our history with a disease called scurvy, common until the 1900's - especially among sailors and those coming to Australia by boat.

Scurvy is caused by a lack of Vitamin C and the symptoms are - lack of appetite, bleeding gums, loose teeth, swollen ankles and tiny bleeding spots or haemorrhages on the skin. Scurvy killed 2 million sailors between 1500-1800. By 1800's it was recognised that eating citrus fruits prevented scurvy but it was not until 1928 that scientists discovered the role of Vitamin C.

Student activity

Introduction:
Cooking and processing can destroy much of the Vitamin C in our foods so let's check how much you can see or detect in some different juices and drinks.

Vitamin C reacts with iodine because it uses the iodine up. If starch and iodine are combined the mixture turns a blue black colour. When a food containing Vitamin C is added, the Vitamin C uses up the iodine so the blue-black colour of the starch-iodine combination disappears.

Materials:

»	Iodine
»	Eye droppers or small plastic teaspoons
»	Starch solution (1 teaspoon cornflour dissolved in 1 cup of boiling water) Make up in advance and allow to cool. This solution will be enough for 8 students.
»	Enough small containers/cups/test tubes to hold liquids (1 for each food item tested)
»	A range of juices to test such as: freshly squeezed lemon juice and orange juice; other fruit and vegetable juices (packaged and fresh, if available), commercial juice drinks and soft drink, crushed vitamin C tablets.

Method:

1.	Predict whether each food/drink will contain Vitamin C.
2.	Place paper towel/newspaper on a table.
3.	Using eye dropper put about 20 drops or ½ small teaspoon of the starch solution in your cup/test tube.
4.	Add 1 or 2 drops of iodine - the water should turn slightly blue.
5.	Add food/drink to the starch-iodine solution.
6.	If the blue disappears the food contains Vitamin C.

Student Connections:
Students are able to explore the world of vitamins through this simple experiment. Some points for discussion and further investigation:

»	Were there any surprising results?
»	Compare the information on the packaged materials with your results - do you agree?
»	Can you devise a way of testing solid foods?
»	Explain why Vitamin C is important in our diet.
»	Investigate why Aboriginal people didn't get scurvy before European Settlement. (Discuss the background to this question, ie. which, if any, of the foods tested are native in Australia?)