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November nutrition news from the Friedman School of Nutrition Science and Policy at Tufts

Molecules and Mysteries: Unraveling ubiquitin for eye health and practice what you read: Adolescents and nutrition labels

Tufts University

--Molecules and Mysteries: Unraveling Ubiquitin for Eye Health--

Most people, scientists included, had not heard of the protein ubiquitin until a few weeks ago when the 2004 Nobel Prize in Chemistry was awarded to three scientists for their groundbreaking work on the subject. While it might not become a household word overnight, the Nobel Prize award certainly means that ubiquitin will become better understood and more prominent in scientific research.

Allen Taylor, PhD, director of the Laboratory for Nutrition and Vision Research, and his colleagues at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, have been researching the role of ubiquitin in eye health since 1982. Taylor describes ubiquitin this way, "ubiquitin, as is implied in its name, is found in every cell in the animal and plant kingdoms. It is like a molecular flag. When ubiquitin is attached to damaged or obsolete cellular proteins, it functions as 'the kiss of death' signaling that these cells with ubiquitin attached should be degraded or removed. This process occurs by what is called the ubiquitin pathway. It is essential that damaged proteins are removed, because if they are not, they accumulate and are toxic to cells - this is what happens during aging."

One contribution by Taylor and other Tufts researchers has been to show that when the ubiquitin pathway functions poorly, damaged proteins accumulate. This can lead to diseases such as cataracts and age-related macular degeneration.

Tufts researchers have also demonstrated that stresses caused by free radicals, molecules which attack ubiquitin and other proteins in the eye, wipe out the benefit-giving ubiquitin pathway. Free radicals are thought to be a fundamental cause of many degenerative diseases and the aging process and can be produced naturally in the body over time, or they can be caused by environmental factors--such as air pollution, cigarette smoking, and pesticides. Antioxidants, found in many fruits and vegetables, prevent further damage in the cell by quenching these free radicals. Taylor and his colleagues are currently examining ways in which nutrients, such as antioxidants, might be used to reduce the stresses in the eye which contribute to the diminished function of the ubiquitin pathway.

"We hope to find a way to extend the lifetime of ubiquitin, and thereby slow down or prevent the onset of eye disease," said Taylor, who is also a professor at the Friedman School of Nutrition Science and Policy at Tufts, and a professor of biochemistry and ophthalmology at Tufts School of Medicine.

Ubiquitin was discovered about 25 years ago, which is not considered to be a long time in science. Taylor notes that since that time, scientists have learned of its role in numerous cell functions. The ubiquitin pathway also plays major roles in many other cellular processes such as cell division, DNA repair, immune functions, and even gene expression, which determines what kind of cell a progenitor , or stem, cell becomes, making it a rich target for research on health, disease and aging.

--Practice What You Read: Adolescents and Nutrition Labels--

Nutrition labels are generally recognized as a good education tool because they enable consumers to make healthy food choices. But what if reading the nutrition labels doesn't help everyone? Terry T.-K. Huang, PhD, research assistant professor from the Friedman School of Nutrition Science and Policy at Tufts, and colleagues, found that adolescents who read nutrition labels did not necessarily translate that information into healthier diets and, sometimes, instead increased fat input.

"Nearly 80% of the adolescents reported sometimes or always reading nutrition labels although it didn't translate into healthier diets. In boys, however, we found that reading nutrition labels was associated with a higher fat intake, while in girls, fat intake did not differ by reading nutrition labels. This is an important finding because fat intake in U.S. adolescents is near the maximum of the recommended daily intake."

Dietary practices at a young age may play a significant role in health and disease later in life, noted Huang, but few studies have evaluated the impact of nutrition labels, especially in younger populations.

The study of more than 300 boys and girls ages 10 to 19, primarily Caucasian and African-American, found that more than 56% reported reading nutrition labels some of the time. Almost 22% reported always reading nutrition labels and nearly 22% reported never reading them. No differences in nutrition label use were found across ethnicities, but African-Americans had more calories from fat than Caucasians. Boys who always read nutrition labels consumed the greatest number of calories from fat.

The research suggests that girls and boys may read nutrition labels for different reasons. The authors note the possibility that boys might read simply to assess total calories or proteins from a desire to "bulk up". Girls, they speculate, might focus on total calories.

"Little has been done to evaluate the influence of the uniform nutrition labels since they were introduced in the United States in 1994. Early nutrition education that takes into account gender-specific issues is clearly needed to help the public better understand and use nutrition labels," said the authors.


Huang, Terry T.K., et al, Journal of Adolescent Health, 2004, 35:399 - 401. "Reading Nutrition Labels and Fat Consumption in Adolescents."

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