Anyone still deciding what's for dinner after a hectic day would envy Candace Ritchie. After her workday, she's served chicken fajitas, spaghetti and meatballs or lemon-herb salmon, all in the name of science and without lifting a pan. It's just one benefit of Ritchie's participation in a Hutchinson Center feeding study looking at the connection between carbohydrates, body weight and cancer.
Ritchie joined the Public Health Sciences Division's Carbohydrates and Related Biomarkers (CARB) study in September. The study is a component of the $18 million Transdisciplinary Research on Energetics and Cancer (TREC) funding that the Center received from the National Cancer Institute last year as part of a nationwide research effort to better understand the link between obesity and cancer.
Co-Principal Investigators Drs. Johanna Lampe and Marian Neuhouser and colleagues are testing how weight and refined (high-glycemic) or complex (low-glycemic) carbohydrates affect biological markers in blood and urine.
"Increasing evidence suggests that obesity is a risk factor for several types of cancer," said Lampe, who is also associate director of the PHS Division's Prevention Center and oversees the Human Nutrition Lab. "Differences in metabolic response to these different diets may ultimately influence cancer risk and help explain the obesity-cancer connection. Using a feeding study where everyone is fed the same carefully defined, controlled diets allows us to measure these metabolic differences more accurately."
CARB participants — a mixture of normal weight and overweight men and women — follow two 28-day feeding periods separated by a 28-day stint of eating their own food.
During the feeding periods, they come to the Human Nutrition Lab in the Arnold Building's Prevention Center on weeknights to eat dinner and pick up breakfast, lunch, beverages, snacks — even gum, candy and condiments — for the following day. On Fridays, meals are packaged and sent home for the whole weekend. Participants are weighed daily, complete several questionnaires weekly and give samples of blood and urine during the study.
During one feeding period, the menu includes sandwiches on white bread, mashed potatoes and watermelon. The other feeding period offers foods such as bran muffins, lentil or black-bean salads and whole-grain pasta.
For Ritchie, an office manager and physical-therapy aide who resides in Bothell, the effort of driving to the Center nightly is outweighed by the luxury of having all of her meals provided. "Not shopping for groceries is great, and it's very convenient not to have to prepare meals for a month at a time," she said. "I live alone, so it does get challenging to get motivated to cook for myself. The study really helps in that department. The food is very good, which makes it easy to stick to the study."
A commitment caveat
Despite the benefits, Yvonne Schwarz, CARB's project manager, warns that committing to a prescribed diet for a month isn't for everyone. "A four-week feeding period is complicated," she said. "People have busy lives, and they have to figure out if there will be any event that could prevent their participation. So much socializing is based around food. And not being able to choose what you're eating is difficult. People think it doesn't matter, but what many people discover is how important choice is once they're on a study like this. If you feel like pasta tonight, you have pasta. You can't do that on a controlled feeding study".
"But we're realistic. The study consists of more than 100 meals, so if you fall off the wagon for one meal or you eat an extra cookie, it is not going to destroy the study. Sometimes people have 'meltdown days' and just can't take it anymore — they have to have that slice of pizza. The real key is to honestly tell us what's going on. We don't want participants to lose or gain weight or be hungry."
The CARB study team includes PHS Division scientist Dr. Gloria Coronado, who lends her expertise in the recruitment and retention of minority participants; the study team hopes to attract a significant number of minority enrollees. Dr. Paul Lampe, head of the Center's TREC Core Lab, conducts proteomic analysis of the blood and urine samples. Dr. John Brunzell, a University of Washington endocrinologist and an expert in the areas of diabetes, energy metabolism, obesity and metabolic syndrome, contributed to the study design and helps interpret participant lab results. McGill University's Dr. Michael Pollak is a world leader in insulin-like growth factor (IGF) physiology, particularly as it relates to cancer development. He runs a reference lab that measures IGFs and related analytes for large epidemiologic studies and conducts these measures for CARB.
The CARB researchers expect enrollment to take about three years, with study results in four to five years. One of their goals is to produce data to inform dietary recommendations. "There have been very few human experimental studies testing low- and high-glycemic diets, yet following a low-glycemic diet has become a popular health trend," Neuhouser said. "We need data to either support or refute its efficacy before specific dietary recommendations can be made."
Lampe said the study design — having each participant eat both kinds of diets — keeps the focus on the pros and cons of low- and high-glycemic foods. "By keeping the caloric level of the diets the same and keeping participants' body weight the same over the four-week feeding periods, we are isolating the effect of the diet composition," she said. "In other words, we are not testing caloric restriction or weight loss, but the actual types of foods."
Between the convenience, compensation and chance to help cancer research, Ritchie said she'd jump at the opportunity to join a study like CARB again, with one caveat: "I think there should be more peanut M&Ms!"
The CARB study seeks healthy, normal-weight and overweight nonsmokers, ages 18-45, for a 12-week study of diet and health. Eat only the food provided for two four-week periods, with weeknight dinners eaten at the Hutchinson Center. No recreational or prescription drugs (including birth control), pregnancy or breastfeeding. Must be screened to participate. Compensation: $750. Call (206) 667-2547 or www.carbstudy.org.