Research
Past Studies
The Nutrition Center staff has been involved in numerous long-term, randomized clinical trials and projects.
Lipid Research Clinics Coronary Primary Prevention Trial (LRC-CPPT)
Purpose: A randomized clinical trial to determine whether lowering cholesterol reduces risk of coronary heart disease (CHD)
Our role: Directed the Food and Nutrition Coordinating Center of the trial, which facilitated cooperative efforts among dietitians in 12 centers.
Dates: 1973 to 1983 with follow-up in 1988
Number in study: 3,806 middle-aged men without CHD and with primary hypercholesterolemia at multi-centers
Sponsor: National Heart Lung and Blood Institute
Outcome: Adherence to drug and diet during trial for our sites was excellent. All 372 patients were involved in follow-up. Study concluded that reducing total cholesterol by lowering low-density lipoprotein cholesterol (LDL-C) levels can reduce risk of CHD morbidity and mortality.
The Diabetes Control and Complications Trial (DCCT)
Purpose: Compare intensive versus conventional insulin therapy in individuals with insulin-dependent diabetes.
Our role: Nutritionists worked as part of a multidisciplinary team to counsel participants using intensive insulin therapy. Dr. Snetselaar designed and presented national nutrition counseling workshops that emphasized a multidisciplinary team approach to normalize blood glucose levels of insulin-dependent diabetes patients while establishing dietary practices to reduce risk of CVD.
Dates: 1983 to 1993
Number in study: 1,441 participants, ages 13-39, with type 1 diabetes at 29 U.S. and Canada sites.
Sponsor: National Institute of Diabetes, Digestive Disorders and Kidney Disease (NIDDK) of the NIH
Outcome: The intensive insulin therapy group had a 50-75% reduction of various complications demonstrating a clear benefit for use of intensive insulin therapy.
Modification of Diet in Renal Disease (MDRD)
Purpose: Randomized clinical trial to study the effect of various dietary protein interventions on the progression of end-stage renal disease: 1) usual protein to low protein; and 2) low protein to very low protein.
Our role: Extremely complex diets required expert skill in compliance monitoring and adherence strategies. A workshop on the single-nutrient approach was provided by the team for all 15 centers' dietitians to expand awareness about behavior change in dietary interventions. Coordinated project at local site.
Dates: 1985-1993
Number in study: 840 men and women, ages 18-70, at multiple sites
Sponsor: National Institute of Diabetes, Digestive Disorders and Kidney Disease (NIDDK) of the NIH
Outcome: For patients with moderate renal disease, starting four months after beginning low protein diet, a slower decrease in renal function suggests a small benefit. For patients with more advanced renal disease, a very low protein diet compared to a low protein diet did not show a significant slowing of renal progression.
Dietary Intervention Study in Children (DISC)
Purpose: To evaluate lipid-lowering diet in children. Follow-up to evaluate the effect of the DISC intervention during puberty on biomarkers strongly associated with breast cancer risk including serum hormone levels, breast density, and bone mineral density.
Our role: With 101 children in the Iowa site, we conducted a family intervention with a series of group and individual sessions where children and families were counseled to follow a diet of the following percent of calories: 28% of fat, less than 8% from saturated fat, up to 9% from polyunsaturated fat, and dietary cholesterol intake of less than 75 mg/1000 kcal.
Dates: 1987 to 1997
Number in study: 663 children, ages 8-10, with elevated low-density lipoprotein cholesterol (80-98th percentile) at six centers.
Sponsor: National Heart Lung and Blood Institute (NHLBI) of NIH
Outcome: At three years, the intervention group showed significantly lower LDL-C, but no significant difference in mean height, serum ferritin, or safety measures. At seven years, there were no significant difference in measurements.
LRC - Lipid Disorders Training Workshop program
Purpose: Teach community physicians and their staff effective management of lipid disorders through two-day workshops that included dietary assessment and counseling, diet and drug therapy, and case-based learning strategies.
Dates: 1990-1996, three to four times per year
Number in study: more than 600 physicians and staff were trained
Sponsor: American Heart Association
Women's Health Initiative (WHI)
Purpose: This massive randomized controlled clinical trial involved 160,000 women in various studies, including hormone therapy, diet modification and calcium/vitamin D supplementation.
Our role: As part of the intervention arm of the diet modification study, nutritionists counseled participants in a group setting to follow a 20% low-fat diet, with 5 or more servings of fruits/vegetables per day and 6 or more grains per day.
Dates: 1993 to 2005
Number in study: In the diet modification arm -- 48,835 postmenopausal women, ages 50-79, at 40 sites
Sponsor: National Cancer Institute (NCI) and the National Heart Lung and Blood Institute (NHLBI)
Outcomes: Based on an average 8.1 years of follow up, the low-fat diet with increased fruits, vegetables and grains did not reduce colorectal cancer risk. It did not significantly reduce the risk of cardiovascular disease. Trends toward greater decreases in coronary heart disease risk, however, were noted for study participants with lower intakes of trans or saturated fat or greater intakes of fruits and vegetables. Additionally, there were small favorable effects of the eating pattern on some cardiovascular disease risk factors such as body weight, LDL cholesterol, and diastolic blood pressure. Finally, the low fat eating pattern did not significantly reduce breast cancer risk. However, there was a non-significant trend suggesting lower risk for the low fat eating pattern group. Additional analyses support this trend. They reveal that women in the low fat eating pattern group who had higher fat intakes at the beginning of the study made larger reductions in fat intake than the group as a whole, and had a greater decrease in breast cancer risk.
Women's Intervention Nutrition Study (WINS)
Purpose: Randomized control trial to determine if low-fat diet reduces risk of cancer returning in postmenopausal women with history of breast cancer.
Our role: Nutrition Center staff coordinated Iowa center study with two off-site locations and counseled intervention participants to follow a 15% low-fat diet.
Dates: 1997 to 2005
Number in study: 2,437 postmenopausal women, ages 48-79, at 39 sites
Sponsor: National Cancer Institute
Outcome: A lifestyle intervention reducing dietary fat intake, with modest influence on body weight, may improve relapse-free survival of breast cancer patients receiving conventional cancer management, especially in those who cancers don't respond to estrogen (ER-negative).
Study of Nutrition in Teens (SONIT)
Purpose: Compare serum ferritin, zinc, and cholesterol levels of adolescents following cholesterol-lowering eating patterns randomly assigned to emphasize lean beef or lean poultry and fish.
Our role: Enrollment, data collection, intervention sessions with students and families were conducted along with a meal.
Dates: 1998 to 2000
Number in study: 86 - 7th and 8th grade students with LDL-C in top half of distribution.
Sponsor: National Center for Research Resources, National Cattleman's Association, General Clinical Research Centers Program, National Institutes of Health
Outcome: Lean beef group ate significantly more beef and both groups reduced total and saturated fat intake. No differences in iron and zinc intake or in serum zinc and cholesterol levels. Ferritin data support including heme-iron-rich lean beef in dietary recommendations for adolescents consuming low-fat diet.
Dietary Intervention Study in Children (DISC 06)
Purpose: Follow-up study to the original DISC study to evaluate the effect of the DISC intervention during puberty on biomarkers strongly associated with breast cancer risk including serum hormone levels, breast density, and bone mineral density.
Our role: We successfully located and completed visits on 55 of 67 (96%) of original Iowa participants.
Dates: 2005-2009
Number in study: 260 of the original 301 women (84.6%) from original study at 6 sites.
Sponsor: National Cancer Institute
Outcome: Analysis in progress
Dietary Intake Study of Complementary and Alternative Medicine Clinic Patients (CAM)
Purpose: To obtain information about the dietary intakes of patients of the Complementary and Alternative Medicine (CAM) clinics at The University of Iowa. Dietary intake of individuals using dietary supplements were compared with those who did not.
Our role: Conducted 24-hour diet recalls with study participants using Nutrition Data System (NDS) software program. Researched nutrient values for dietary supplements of food items not included in NDS database. Counseled study participants regarding health-promoting eating practices using evidence-based research.
Dates: 2006-2007
Number in study: 48 CAM clinic patients
Sponsor: National Institutes of Health
Outcome: Results are pending.