Here are three questions on which to try your chemical detective skills using the web the web by searching for "lactose intolerance". Reading the labels in your cupboard or at a nearby store can also help you milk out some information.

a. Over-the-counter digestive aids allow you to increase your intake of dairy products. How do these work? What are their advantages and disadvantages?
b. Even with digestive aids, you may risk not getting enough calcium, an essential mineral that you will learn more about in Section 11.11. What other foods can you eat in order to obtain enough calcium in your diet?
c. Sometimes lactose turns up in foods in which you least expect it, such as bread. Although lactose may not be listed on the label, you will see ingredients such as whey, milk products, nonfat dry milk or dry milk solids -- all of which contain lactose. Find three other non-dairy foods that you may have to watch out for if you are lactose intolerant.

Have the recommendations of the American Heart Association for cholesterol, HDL and LDL changed from those reported in this section? Check the current recommendations at their web site. If there are any differences, explain why.

In spite of FDA approval, the use of Olestra (Olean) in snack foods remains controversial, with both supporters and detractors. To learn more, first check out the extensive Olean web site, sponsored by the company that markets Olean. Then search for "Olean" and "Olestra" together with terms such as "controversy", "opposition" and "drawbacks" to bring up web sites that present other viewpoints. Use the information you find together with that provided in the text to answer these questions:

a. What are the main points of contention between the two sides?
b. What complaints have actual Olestra consumers registered?
c. Do you think that their complaints were justified, given the information provided? Explain.
d. Will consuming food containing fat substitutes always result in weight loss? Explain.
e. What is your personal decision about using products containing Olestra? Explain your reasoning.

Hint: Olean sites that highlight the controversies may be difficult to locate. Try switching to other search engines if your first search isn't fruitful. Here are three starting points, one from the Mayo Clinic, another from Ohio State University and a final one from the Center for Science in the Public Interest.

Structural features of amino acids are more readily apparent if you look at their three-dimensional representations. Here are the molecular structures for several amino acids: glycine, alanine, phenylalanine, leucine, cysteine, aspartic acid, and the entire set. Note: To view the molecules, you will need to install a "plug in" called CHIME.

a. How is the three-dimensional structure of glycine different than the two dimensional structure shown in your text?
b. Glycine is the most simple amino acid. It contains only two functional groups (-NH₂ and -COOH) and only the elements C, H, O and N. Browse through the entire set of amino acids and then describe two ways in which their structures are more complex than glycine's.
c. In leucine, what four different groups are bonded to a central carbon atom? Is this molecule optically active? Explain your answer.

Food irradiation remains controversial. The Foundation for Food Irradiation Education, a web site under development in 1999, claimed that the web provides "a unique opportunity to communicate the facts about food irradiation to journalists, educators, food company executives and the general public". Indeed, the web can link together a host of constituents with differing viewpoints on a topic such as food irradiation. Use the web to prepare a position paper on whether or not food should be irradiated. You may write as a food company executive, a manufacturer of radiation equipment, a government official, or a consumer activist. Be sure to cite your sources. Later, you may wish to join with others taking your position to stage a class debate about the issues involved.