She and colleagues examined trends in weight control behaviors over a 10-year period in U.S. high school students. In 2005, nearly 27 percent of teenage boys reported dieting and almost 5 percent used diet products, up from 16 and 2 percent, respectively, in 1995, they report in the International Journal of Eating Disorders.

Teen boys similarly showed an increasing trend in their use of exercise for weight control over the 10-year period. Hispanic boys were the most likely to practice weight control, followed by black, then white boys.

The results, the researchers say, add to the growing evidence that boys and men, regardless of ethnicity, are at risk for developing harmful weight control behaviors.

"The increased numbers of boys who report body image concern is worrisome in part because health professionals may not be prepared to detect such problems among boys," Striegel-Moore noted.

Among girls, the overall prevalence of dieting increased from nearly 48 to almost 55 percent, but black girls tended to show less of a concern with 'thinness' than did Hispanic and white girls.

Future studies need to investigate possible explanations for the different weight control practices among different ethnic groups of teenagers, as well as the increasing trend of weight control practices among male adolescents, the investigators conclude.

SOURCE: International Journal of Eating Disorders, November 2007

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Green tea may protect against colon cancer

Last Updated: 2007-12-07 12:18:30 -0400 (Reuters Health)

By Megan Rauscher

NEW YORK (Reuters Health) - An extract of green tea wards off colorectal cancer, animal experiments show.

According to research reported at the Sixth International Conference on Frontiers in Cancer Prevention, sponsored by the American Association for Cancer Research, a standardized green tea polyphenol preparation (Polyphenon E) limits the growth of colorectal tumors in rats treated with a substance that causes the cancer.

"Our findings show that rats fed a diet containing Polyphenon E are less than half as likely to develop colon cancer," Dr. Hang Xiao, from the Ernest Mario School of Pharmacy at Rutgers University, Piscataway, New Jersey, noted in a statement.

These results are consistent with previously published results, which showed that green tea consumption was associated with lower colon cancer rates in Shanghai, China, he also noted.

In the study, Xiao and colleagues injected rats with azoxymethane, a chemical known to produce colorectal tumors that share many characteristics with colorectal cancer in humans. Then they fed the animals a high-fat Western-style diet with or without Polyphenon E for 34 weeks. The amount of Polyphenon the animals took in was roughly equal to about four to six cups of green tea per day.

Polyphenon E decreased the total number of tumors per rat and decreased tumor size, compared with control rats that were not given Polyphenon E, Xiao told the conference.

"In the control group," he said, "67 percent of rats developed malignant tumors while in the treated group only 27 percent of rats had malignant tumors. Most important, tea polyphenols decreased the number of malignant tumors per rat by 80 percent compared to the control group."

When the researchers analyzed blood and colon tissue samples, they found a "considerable amount of tea polyphenols in those samples in treated animals, and those levels of tea polyphenols were comparable to the human situation after ingestion of tea leaves or tea beverage," Xiao noted.

The researchers believe these findings will pave the way for clinical trials with green tea polyphenols in humans.

Copyright © 2007 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.