Center Overview
Overall Aim: The purpose of this center proposal is to conduct transdisciplinary research, training, and outreach on obesity and cancer in youth, families, and young adults. The Center will address questions about the etiology, prevention, and treatment of obesity in youth and families, and explore biological pathways that may link obesity to cancer. The center includes three specific research projects.
Projects: Project 1 is a multifactorial, cross-sectional, prospective observational study examining predictors of obesity development in adolescents, including sociocultural factors, family factors, environmental factors, and individual factors. Project 2 is a study evaluating a family-based weight-gain prevention intervention that particularly emphasizes intervention on environmental contributors to weight gain. Project 3 is a study of the effects of physical activity on estrogen metabolism, oxidative stress, and DNA repair mechanisms in young women.
Summary and Significance: The three R01 grants will be supported by two cores, an Administrative Core and a Data Services and Analysis Core. There is also a career development component, substantial funding for developmental projects, and a dissemination/translation component. The overall goals are to advance transdisciplinary science in the advancement of understanding of obesity, youth, family, and cancer; to support the career development of new investigators in the field; and to disseminate scientific knowledge about the topic to broader audiences.
Project 1: Etiology of Adolescent Obesity
Co-Director: Leslie A Lytle
Overall Goal: This research will examine cross-sectional and prospective predictors of adolescent obesity using a social-ecological framework.
Design: We will recruit 420 youth and one of their parents from an existing cohort in the Minnesota Adolescent Community Cohort (MACC) study. The MACC cohort is a representative sample, drawn from 60 geopolitical units throughout the state of Minnesota, and has been followed for 4 years as part of a study examining the effects of state and local tobacco programs on youth tobacco use. Dr. Jean Forster is the Principal Investigator for this ongoing study. For our TREC research, we will invite students in the MACC cohort who are 15 to 16 years old and live in the metro area of Minneapolis and St. Paul to be involved in this study of the etiologic factors of obesity in adolescents.
Specific Aims: We will assess potential obesogenic factors at the individual, family, school, and community levels by collecting data at three time points over a period of 24 months. Individual measures will include anthropometry and a variety of psychosocial, preference, and behavioral assessments related to eating and activity.
Measures: Family measures will include family socioeconomic status, parent weight and body composition, family meal and activity patterns, and the home food and activity environments. School level measures will include opportunities for physical activity, competitive food availability, and school food and activity policies. Community-level measures will include the use of Geographical Information System (GIS) to assess obesogenic environmental factors such as the presence of walking and bike paths, convenience stores, and fast food restaurants.
Significance: This research is multidisciplinary, involving researchers from four departments at the University of Minnesota (the Division of Epidemiology, the School of Nursing, the School of Kinesiology, and the College of Architecture and Landscape Architecture) and including scientists with an expertise in the biological sciences, exercise physiology, nutrition, the behavioral sciences, psychology, and urban planning. This research will be the first in a series of proposed studies; another such study would follow the cohort into young adulthood to assess obesity risk and related cancers, while another would help direct the focus of future interventions to prevent the onset of childhood overweight and obesity and reduce chronic disease risk.
Project 2: Household Environmental Weight Gain Prevention
Project Leader: Simone A. French
Overall Goal: Obesity is a national epidemic that is widely recognized to be environmental in origin. Primary prevention interventions that address both environmental and individual-level influences on obesity are urgently needed. The primary aim of this study is to evaluate a household-level weight-gain prevention intervention that includes both environmental change and individual-level behavior change components.
Design: Four hundred forty households will be recruited and randomized to one of two groups for a 1-year period:
- Household environmental weight-gain prevention program; or
- Control program that provides only general behavioral weight control recommendations.
The primary outcome is household-level change in body weight over the 1-year intervention period. The household environmental weight-gain prevention program includes reduced access to television viewing by use of a television time-limiting device; reduced household availability of high fat/energy prepackaged foods and less frequent fast food restaurant use; and increased frequency of self-weighing with the provision of a home scale to each household. In addition, the individual-level behavioral change component targets specific eating and exercise behaviors that dovetail with the household environmental changes to promote weight control. The intervention program format consists of 6 monthly face-to-face group meetings, 12 monthly newsletters, 6 encouragement telephone calls, and continuous access to intervention staff via telephone and e-mail. The control group program consists of 12 monthly newsletters that provide general behavioral recommendations for weight control. The primary outcome is household-level percent weight change measured one year after initiation of treatment. Secondary outcomes are changes in energy intake, physical activity, television viewing time, and frequency of self-weighing.
Significance: It is hypothesized that intervention households will gain significantly less weight over the 1-year intervention period than households randomized to the control group.
Project 3: Women in Steady Exercise Research (WISER)
Project Leader: Mindy Kurzer
Overall Goal: It is not feasible to conduct randomized controlled exercise intervention trials with breast cancer diagnosis as the primary outcome. Therefore, it is of interest to determine whether exercise will alter physiologic outcomes associated with breast cancer incidence, including oxidative stress, estrogens, estrogen metabolism, and metabolic factors such as body fat, elevated fasting insulin, insulin resistance, alterations in plasma levels of IGF-axis proteins. We propose to examine the effects of aerobic exercise training on each of these mechanisms among young (18-30 years), pre-menopausal, eumenorrheic women in a randomized controlled trial. The primary hypothesis to be tested is whether exercise alters oxidative stress as measured by F2-Isoprostanes. The innovation of this grant stems from the concurrent measurement of cancer biomarkers, which will enable us to explore relationships between changes in these physiologic parameters that may have an important role in the exercise—cancer link. Compelling preliminary data indicate that the amount of exercise recommended for health promotion and chronic disease prevention (5 weekly 30 min sessions of moderate intensity aerobic exercise) may alter these risk factors in a manner consistent with reduced cancer risk.
Design: We will recruit 400 women and anticipate a dropout rate of 20%, for a final sample of 320 women (n=160 per group). Measurements will be made from days 7 to 10 of the participants’ menstrual cycle prior to randomization and at the 5th menstrual cycle after the baseline cycle. Participants will also use ovulation kits to determine whether exercise alters luteal phase length or ovulatory status. Measurements will include oxidative stress (F2-isoprostanes), estrogen metabolites, body composition (dual energy x-ray absorptiometry), insulin, glucose, and insulin resistance (HOMA index), insulin-like growth factor axis proteins (IGF-1, IGFBP-1, -2, and -3), submaximal fitness, questionnaires (injury/illness, demographics), and diet (by food frequency questionnaire).
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