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In this Edition:
Childhood Obesity Intervention Shows Promising Results; Dietary Preferences and Patterns May Be Linked to Genes, Says Research; Lack of Sun Does Not Explain Low Vitamin D in Elderly Who Are Overweight
The Latest Information Coming from the Friedman School of Nutrition Science and Policy at Tufts University
Boston – May 10, 2007 –Shape Up Somerville: Eat Smart. Play Hard.™ a community-based environmental change intervention to prevent obesity in culturally diverse, early elementary school children reduced weight gain over one school year. The multi-faceted program was designed and implemented by researchers from the Friedman School of Nutrition Science and Policy at Tufts University and the Tufts University School of Medicine in close collaboration with the community. The first year results reflect efforts of children, parents, teachers, school food service providers, health care providers and policy makers, as well as city departments, before-and-after school programs, restaurants, and local media outlets to provide and promote healthy eating options and physical activity among elementary school-aged children in Somerville, Massachusetts.
Corresponding author Christina Economos, PhD, assistant professor and New Balance Chair in Childhood Nutrition at the Friedman School, and colleagues used a measure called BMI-z score (or BMI-for-age percentile)* to report a reduction in weight gain among children who participated in the Shape Up Somerville (SUS) intervention, as compared to children in two socio-demographically similar communities in Massachusetts who did not receive the intervention.
"On average, SUS reduced approximately one pound of weight gain over eight months for an eight-year-old child. This may seem small for an individual, but on a population level this reduction in weight gain, observed through a decrease in BMI z-score, would translate into large numbers of children moving out of the overweight category. Such a reduction is important given today’s obesigenic environment where the shifts continue to be observed in the opposite direction," says Economos.
A key element of the intervention was the work done in collaboration with Somerville schools. Economos and her team planned and implemented a range of initiatives designed to provide and promote healthy eating options and physical activity. These included:
- Work with the school food service director to offer healthier foods, develop more healthful recipes, and promote consumption of new foods through interactive education programs in the cafeteria
- An after-school curriculum that included creative cooking, cooperative games, yoga, soccer, and field trips, including a farm visit to learn how food is grown
- An in-class curriculum with all first through third grade teachers that included daily "cool moves" sessions, weekly nutrition and physical activity lessons, and fun and healthy giveaways
- Evaluation and expansion of school wellness policies, such as those that impact school health and physical education environments, and pedestrian safety
The intervention went well beyond the Somerville schools. Parents and community members were encouraged to participate through school, after-school, and community events. There were parent forums to engage members of the four major language communities in Somerville: English, Spanish, Portuguese, and Haitian-Creole, newsletters with health tips, walking contests, traffic calming campaigns, and coupons for healthy foods. The SUS team also worked with school and community officials to establish a city employee fitness and wellness benefit. School nurses, pediatricians, and family physicians were trained to address issues of overweight and obesity among children. SUS also collaborated with 21 local restaurants to develop the SUS stamp of approval, which indicates that the restaurant offers healthy menu options.
"If this seems like a very large number of activities, it is," says Dr. Economos, "but we believe that it is the sum of these efforts that will guide children to form habits that prevent excess weight gain as they move into their teenage and adult years. Many programs offer nutrition and physical activity education, but SUS also worked with individuals and community organizations that shape a child’s environment, improving the chances that the healthful changes they make will last."
Community interventions such as SUS are not without challenges, says Economos. "SUS researchers spent several years building relationships within the Somerville community before the intervention could be implemented." The researchers were only able to measure and follow BMI z-scores for approximately 60 percent (385/631) of students assigned to the intervention community mainly because children moved out of the area. Economos concludes, however, that "Creating programs like SUS for communities is essential as the US obesity rates have more than tripled in children in the last three decades. Furthermore, given the intractable nature of the condition once established, proactive strategies that begin during childhood are needed to prevent overweight."
Co-authors are Raymond R. Hyatt, Jeanne P. Goldberg, Aviva Must, Elena N. Naumova, and Miriam E. Nelson, all of Tufts University, and Jessica J. Collins, formerly the project manager on the Shape Up Somerville: Eat Smart. Play Hard.™ study, which was largely funded by the Centers for Disease Control and Prevention. Additional support was provided by Blue Cross and Blue Shield of Massachusetts, Inc. and Blue Cross and Blue Shield HMO Blue of Massachusetts, Inc., United Way of Massachusetts Bay, the United States Potato Board, Stonyfield Farm, and the Dole Food Company. The New Balance Chair in Childhood Nutrition at the Friedman School is funded by the New Balance Foundation.
* Body mass index (BMI) is the relationship between height and weight. (BMI)-for-age, expressed as a z-score or percentile, indicates the relative position of the child’s BMI number among children of the same sex and age. A BMI z-score between the 85th and 95th percentile is considered at risk for overweight, while a BMI z-score at or above the 95th percentile is considered overweight. Standardized BMI z-scores and the corresponding percentiles were constructed by the Centers for Disease Control and Prevention based on historical child heights and weights.
Economos CD, Hyatt RR, Goldberg JP, Must A, Naumova EN, Collins JJ, Nelson ME. “A Community Intervention Reduces BMI z-Score in Children: Shape Up Somerville First Year Results.” Obesity. (May) 2007;15(5).
If you are a member of the media interested in learning more about this study, please contact Christine Fennelly at 617-636-3707 or via email to Christine.Fennelly@tufts.edu.
Boston — The relative amount of protein, carbohydrate, and fat that people choose to eat may be influenced by genetics, according to new research. Jose Ordovas, PhD, director of the Nutrition and Genomics Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University (USDA HNRCA), and colleagues found that the apolipoprotein A-II gene (APOA2) is associated with proportions of fat, carbohydrate, and protein in the diet, along with total calories and, therefore, with body-mass-index ( BMI). These results, published in Clinical Chemistry, are the first to show that the APOA2 gene is linked to food preferences that shape dietary patterns, particularly preferences for dietary fat.
Ordovas, corresponding author, and colleagues analyzed genetic alleles, or variants, in the APOA2 promoter, a region that controls expression, or behavior, of the APOA2 gene. The alleles of the APOA2 promoter, T and C, form combinations; TT, TC, and CC, which indicate genotype. Of more than 1,000 study participants, approximately 85 percent had the common TT and TC genotypes, whereas 15 percent of participants had the CC genotype. “Both men and women with the CC genotype had a statistically significant higher intake of fat than people with the TT and TC genotypes,” says Ordovas. “People with the CC genotype also consumed an average of 200 more calories per day and were nearly two times more likely to be obese, as compared to those with the two more common alleles.”
In addition to preference for dietary fat, the researchers found evidence that the APOA2 gene influences preferences for protein and carbohydrate. People with the CC genotype consumed higher absolute amounts of protein and lower absolute amounts of carbohydrate than those with the TT and TC genotypes. “People with the CC genotype also exhibited dietary patterns with a lower amount of carbohydrate relative to fat and protein than people with the TT and TC genotypes,” says Ordovas, “despite their caloric intake or BMI.”
Study participants, who were part of the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) Study, funded by the National Institutes of Health, were asked to fill out dietary and lifestyle questionnaires. Researchers measured participants’ weight, height, and waist and hip circumference, along with blood lipid levels both before and after a high-fat meal.
The researchers did not find an association between any alleles of APOA2 and blood lipid levels, including triglycerides, total cholesterol, or LDL or HDL cholesterol. People with the CC genotype, however, did have greater amounts of small HDL cholesterol particles, as compared to larger HDL cholesterol particles, in their blood after eating the high-fat meal than did people with at least one T allele. Small HDL cholesterol particles are more of a risk factor for cardiovascular disease than are larger HDL particles.
“This study adds to our understanding of the relationship among nutrition, genetics, and obesity,” says Ordovas, who is also a professor at the Friedman School of Nutrition Science and Policy at Tufts. “Nutrients from the foods we eat activate proteins in our body, which in turn bind to promoter regions, like the APOA2 promoter. These promoters then tell our genes how to behave,” he explains. “Understanding these relationships may help to shape future recommendations for prevention of undesirable health outcomes, especially in populations that may be genetically vulnerable to certain dietary patterns or specific nutrients. More studies are needed in diverse populations to determine if APOA2 might play a role not only in food preferences, but also in satiety signaling.”
This work was supported by a grant from the National Heart, Lung, and Blood Institute, part of the National Institutes of Health. It was also supported by the U.S. Department of Agriculture Agricultural Research Service, the chief scientific research agency of the USDA; Ministerio de Educacion, Spain; and Centro de Investigacin Biomdica en Red (CIBER) from the Instituto de Salud Carlos III (ISCIII), Spain.
In an earlier study investigating the link between genes and diet, Ordovas found that, for most adults in the Framingham Heart Study, fat intake was associated with BMI. However, for 13 percent of the study population with a specific allele of the apolipoprotein A5 gene (APOA5), higher dietary fat was not related to a greater BMI. For more information on APOA5 and Ordovas’ research at the USDA HNRCA, please see “Study Finds Dietary Fat Interacts with Genes” in the March-April 2007 issue of Friedman Nutrition Notes and “Genes and Diet Linked to Risk Factors for Heart Disease” in the September-October 2006 issue of Friedman Nutrition Notes.
Corella D, Arnett DK, Tsai MY, Kabagambe EK, Peacock JM, Hixson JE, Straka RJ, Province M, Lai C-Q, Parnell LD, Borecki I, Ordovas JM. Clinical Chemistry. 2007 (June);53(6):1144–1152. “The-256T>C Polymorphism in the Apolipoprotein A-II Gene Promoter Is Associated with Body Mass Index and Food Intake in the Genetics of Lipid Lowering Drugs and Diet Network Study.”
Lack of Sun Does Not Explain Low Vitamin D in Elderly Who Are Overweight
BOSTON It’s not yet clear why overweight elderly adults have low levels of vitamin D in their blood. However, researchers at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University (USDA HNRCA) have found that lack of sun exposure may not account for low levels of vitamin D in elders who are overweight.
“People aged 65 and over with high percent body fat have lower levels of 25-hydroxyvitamin D, the storage form of vitamin D, compared to those who have lower percent body fat,” says corresponding author Susan Harris, DSc, epidemiologist in the Bone Metabolism Laboratory at the USDA HNRCA.
Harris and co-author Bess Dawson-Hughes, MD, director of the Bone Metabolism Laboratory at the USDA HNRCA, interviewed 381 Caucasian men and women aged 65 and over about their sun exposure over a previous three-month period. Individuals reported how much time they spent outdoors, how much skin was exposed while outdoors, and whether or not they wore sunscreen. Seasonality, or when the individual entered the study, was also taken into account, because in Boston, where the study was conducted, sun rays are weak in winter compared with summer months. The researchers measured participants’ percent body fat using dual-energy x-ray absorptiometry ( DXA), a precise method for determining body composition. Individuals were grouped into quartiles of percent body fat: less than 28 percent, 28 percent to 33 percent, 34 percent to 40 percent, and greater than 40 percent. Blood levels of 25-hydroxyvitamin D were measured and participants were asked to fill out a dietary questionnaire to measure the amount of vitamin D they obtained from food.
Harris and Dawson-Hughes found that when adjusted for sex, age, seasonality and dietary vitamin D intake, 25-hydroxyvitamin D significantly decreased as body fat increased, (P
Vitamin D is called the "sunshine vitamin" because it is produced by the body when the skin is exposed to ultraviolet ( UV) rays from the sun. Vitamin D can also be obtained from foods such as fish and fortified milk and from supplements. When this fat-soluble vitamin enters the body it is converted in the liver to 25-hydroxyvitamin D. This is one of several important forms of vitamin D, and is the form that researchers and clinicians use as an indicator of vitamin D status in individuals. "Vitamin D is especially critical in maintaining bone health, and there is evidence that many older Americans have low blood levels of vitamin D, which can put them at risk for bone fractures and osteoporosis," says Dawson-Hughes, who is also a professor at Tufts University School of Medicine.
"These results cannot be carried over to other populations, such as young people, or elderly living in different climates. However, if low vitamin D stores are not attributed to low sunlight exposure in this population, it suggests that we should explore other possibilities," says Harris. "The most likely explanation seems to be that vitamin D is sequestered in fat tissue, reducing its entry into the blood."
This study was supported by the Agricultural Research Service of the U.S. Department of Agriculture and by a grant from the National Institutes of Health.
Harris SS, Dawson-Hughes B. Journal of Clinical Endocrinology & Metabolism. Electronic version May 2007 doi:10.1210/jc.2007-0702. "Reduced Sun Exposure Does Not Explain the Inverse Association of 25-Hydroxyvitamin D with Percent Body Fat in Older Adults."
The Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy at Tufts University is the only independent school of nutrition in the United States. The school's eight centers, which focus on questions relating to famine, hunger, poverty, and communications, are renowned for the application of scientific research to national and international policy. For two decades, the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University has studied the relationship between good nutrition and good health in aging populations. Tufts research scientists work with federal agencies to establish the USDA Dietary Guidelines, the Dietary Reference Intakes, and other significant public policies.
If you are a member of the media interested in learning more about these topics, or speaking with a faculty member at the Friedman School of Nutrition Science and Policy at Tufts University, or another Tufts health sciences researcher, please contact Siobhan Gallagher at 617-636-6586 or by email to Siobhan.Gallagher@tufts.edu, or Christine Fennelly at 617-636-3707 or by email to Christine.Fennelly@tufts.edu.