Nutrition hotline: this issue's Nutrition Hotline teaches you how to do your own nutritional analyses, addresses concerns about vegetarianism and eating disorders, and discusses good dental hygiene for vegetarians.

QUESTION: "I was wondering if my son and I and possibly some of our friends could learn how nutritional analyses for recipes are done. (We're studying chemistry.) Are they done in a lab or someone's home?" J.M., MD

ANSWER: Actually, the recipes are not directly analyzed using chemistry. The USDA has a large database containing the results of lots of laboratories' work analyzing different nutrients in food. There are computer programs that use this information to calculate (estimate) the nutritional content of recipes. If you want to see USDA's database, go to their website at <http://www.nal.usda.gov/fnic/foodcomp/> and choose the "search for values" section. As you'll see, the USDA database has nutrient values for many foods.

If you want to look at the food you eat for a whole day, it's easiest to either create a spreadsheet and input values from the USDA or use nutrient analysis software. There are a number of commercial programs, as well as a free web-based program, which is pretty simple to use. It is available at <http:llwww.ag.uiuc.edu/food-lab/nat/>.

It may be a bit challenging to analyze foods yourself since many of the vitamins and minerals are present only in very small quantities and one would need to use fairly precise techniques and instruments to quantify them. If you live near a college or university with a food science department, you may be able to arrange a visit to their labs.

I've tested foods for fat and carbohydrates with my children. We did not quantify amounts but just tested for the presence of these nutrients. You can also test for protein and iron. Good For Me! All About Food in 32 Bites by Marilyn Burns has tests for fat and starch, Science Experiments You Can Eat by Vicki Cobb has tests for starch and iron, and Blood and Guts." A Working Guide to Your Own Insides by Linda Allison has tests for protein, fat, and starch.

QUESTION: "It's often said that when teen girls are vegetarian, it is a sign of a food problem. I wonder if:" 1) they are really vegetarian, but 2) more interestingly, are you really more likely to develop a food problem if you are vegetarian than if you're not vegetarian?" C.S., MD

ANSWER: Eating disorders, like anorexia nervosa and bulimia, affect approximately 5-10 percent of young women and fewer than 5 percent of young men. Several studies have suggested that vegetarians are more likely to have eating disorders. In one study, compared to non-vegetarians, vegetarian teens were more likely to be frequent dieters, go on eating binges, induce vomiting after eating, and use laxatives for weight control. Another study found that teens who described themselves as vegetarian (half of whom ate meat and therefore were not really vegetarian) were more weight-conscious and more likely to have been told they had an eating disorder.

Does vegetarianism cause these eating disorders? Probably not. Apparently people who already have eating disorders choose vegetarian or partial vegetarian diets as one more way to restrict food and as a way to hide their eating disorder. One study found that vegetarianism was begun before the onset of anorexia nervosa in only 6 percent of cases. That said, if you are concerned that you or someone you care about might have an eating disorder, seek professional help.

QUESTION: I am going to ask my mother to make an appointment with a dentist to take care of two decayed teeth, and I am concerned she will blame my "starchy" vegetarian diet. What will I tell Mom? M., via e-mail

ANSWER: The most important way to prevent cavities is to brush your teeth often and well and floss daily. Your diet does have some effect, especially if you snack on dried fruits, candy, and other sticky foods. Brushing your teeth or rinsing your mouth well with water after eating these foods will help to protect your teeth. Avoid sugary drinks (sodas, juice) or frequent sucking on candy and mints. I think that if you work on these things and try to eat a healthy vegetarian diet (some starches but also fruits, vegetables, dried beans, nuts, etc.), you can reduce your risk of getting more cavities. Try talking to your Mom about the positive things you are going to do to improve your diet and your dental hygiene. Here's a website with lots of information about teeth: <http://www.nlm.nih.gov/medlineplus/ency/article/001055.htm>.