Be smart! Should I believe all the advertisements say?

1. Be smart! Should I believe all the advertisements say? Click the links below to access the activities: - Activity 1 - Activity 2 - Activity 3 - Extension activity

2. Source﹕Volleyball Association of Hong Kong, China What kinds of diet do they need? Dietary requirement varies with age, occupations, sex…

3. What kind of diet do you need?

4. Do you need food supplements?

5. “… the most useful protein supplement ever, it enlarges every muscle that you want it to… contains the best quality nutrients, it facilitates protein uptake after exercise and improves muscle strength, you will certainly love it” Activity 1: Do you require a high-protein diet? Have you seen advertisements like these?

6. Why is protein so important to us?Which kinds of people may need supplements? Think!

7. Can all protein consumed be stored in the body for muscle building? Are there any factors contributing to muscle size?

8. Why this product targets at vegetarians? Do they need such products?

9. Activity 2: How much protein do the food products contain? Does the food contain the amount of protein as claimed?

10. Methods for testing protein • Biuret test • blue solution changes to purple when reacted with protein • protein concentration can be measured by the intensity of the purple colour

11. Biuret solution Procedure (Biuret test) Protein standards

12. control Colorimeter Procedure (Biuret test)

13. Albustix paper • The colour change depends on the concentration of protein in a food sample

14. Albustix paper Milk product Procedure (Albustix paper)

15. Which test will you use? Why? What are the criteria for choosing a test?

16. A perfect test never exists. Scientists do not always choose the most accurate test. We may choose a test because of ease but sometimes the choice is depends on other reasons. Scientists have to be flexible.

17. Read the food label of the food product. Write down the protein content claimed. Measure its actual protein content. How do the two values compare?

18. Example: • Kjeldahl method • the reference method of many international organizations • gives an accurate amount of protein in any food How can scientists measure protein concentration accurately? Chemists have developed various other techniques to measure protein concentration in food and other substances.

19. Scientists improve techniques to get the most reliable and accurate (reproducible) results.

20. What drives the development of science and technology? Protein is essential for cell structure in all living things, it forms enzymes, hormones and body parts! Why have scientists developed more than one method to measuring protein content accurately? Development in technology and science is often driven by human needs.

21. Is the actual protein content the same as claimed in the food label? We must keep an eye on the actual food content of a product! News report: Australia-sold Ribena Vitamin C contents lower than labelled Hong Kong products claimed label true MingPao 22nd March 2007 The popular drink Ribena which claims that blackcurrants contain 4 times more vitamin C than fresh orange is accused of confusing Australian consumers with incorrect food labels. The manufacturer admits that the vitamin C contents of some instant drinks are lower than what the food labels claim. In Hong Kong, Ribena assures us that the contents of all products match with those claimed in the food labels. The Food and Environmental Hygiene Department and the Customs and Excise Department will follow up on the issue. The Australian Competition and Consumer Commission issued a statement yesterday in which GlaxoSmithKline, Australia admitted that the vitamin C contents of some instant Ribena products fell below those printed on food labels. The company has agreed to stop promotion using the words ‘blackcurrants contain 4 times more vitamin C than fresh oranges’. They promised that only tested contents would appear on food labels…

22. Two 14-years old students! Who did the test in Australia? Scientific discoveries rely on curiosity and questioning.

23. …the words ‘blackcurrants contain 4 times more vitamin C than fresh oranges’ was criticized by the Commission. It misled consumers to think that Ribena’s product contains 4 times more vitamin C than orange juice. Graeme Samuel, the chair of the Commission, pointed out that it’s important for manufacturers to properly indicate contents of food and drinks. In Hong Kong a Ribena representative disagreed with the statement, ‘The sentence compares blackcurrants and oranges, not Ribena and orange juice’. “ blackcurrants contain 4 times more vitamin C than fresh oranges” Is this slogan misleading? Be critical!

24. Is soy protein so incredible? Activity 3: Incredible food: Soy (Soya) Protein

25. Scientists review other scientists’ work Does the US Food and Drug Administration (FDA) allow the health claims made in the advertisement for the product? How does the US FDA verify a health claim?

26. Do scientific theories change? Compare statements made by the US FDA and the American Heart Association! Why has the knowledge about the health effect of soy protein been re-evaluated?

27. Scientific knowledge is subject to change Scientists continually review knowledge as new evidence appears

28. The virus causing SARS Coronavirus Paramyxovirus The cause of stomach ulcer bacteria stress Scientific knowledge is constantly changing… Can you name some examples?

29. Are there any drawbacks in consuming Soya protein? Is the Soya genetically modified? Does the Soya contain any substances that may be harmful to human health?

30. Extension: Are “health food products” healthy? • There are so many health food products available in the market such as those in activity 3. • If you were scientists working for the Consumer Council,how could you assess the health claims of the products?

31. Are there any problems in your design? Does your investigation involve animal / human testing? Any problems with that?

32. What have you learned through the process of designing your investigation? Scientists often encounter challenges in conducting research. Scientists have to be flexible. Ethical considerations are always important in scientific research.