Cancer Dietary Objectives Study (CanDo)

Summary of Grant:

Several studies have demonstrated that poor dietary quality is associated with obesity and certain cancers, such as gastrointestinal, colorectal, and hormonal cancers. Dietary interventions aimed at improving diet are plagued by poor adherence, possibly due to the complexity of changing multiple diet components. Complex public health messages are associated with worse adherence and reduced capacity to impact health outcomes. If a simple public health recommendation for diet was effective at changing multiple aspects of diet, adherence and impact could be maximized. However, research has yet to test which single dietary message has the greatest impact on overall diet quality, and consequently, potential for cancer and heart disease prevention. Thus far, dietary interventions have tested varying combinations of multiple recommendations; however, a single dietary recommendation may have a synergistic beneficial effect on other areas of diet, precluding the need to make the message overly complex.

The present study compares 3 dietary change conditions that are hypothesized to have high potential for synergistic effects on other unaddressed areas of diet, and consequently overall dietary quality. Patients were randomized to one of three arms:

1. low saturated fat diet (≤7% of total calories);
2. high fiber diet (≥30 grams of total fiber per day);
3. combination arm: low saturated fat and high fiber.

Each participant was instructed to reduce calories by -500 kcal/day from his/her resting metabolic rate (RMR), but total calories was not less than 1200 calories per day.

Additionally, Dr. Ira Ockene, professor of medicine, director of preventive cardiology program, generously offered to pay for blood draws and blood lipids and glucose analysis at each visit to make the study valuable from both cancer and heart disease research perspectives.

Specific aims:

1. Develop intervention materials. Intervention materials that specifically aid participants towards a low saturated fat or high fiber diet, or combination change developed for each condition.
2. Preliminary test of intervention. We will calculate change in diet quality, lipids, body weight, waist circumference, and blood pressure at 3- and 6-months. We hypothesize that the single change conditions will produce more changes than the complex condition and that adding beneficial high fiber foods to the diet will result in improved dietary quality (measured by the Alternative Healthy Eating Index) than reducing saturated fat. Secondary outcomes include calorie intake, micro- and macronutrients at baseline, physical activity, and observe changes at 3- and 6-months.
3. Adherence. We will examine adherence to the treatment protocol so that appropriate adjustments to the intervention can be made, if necessary, to enhance adherence in the larger randomized clinical trial.
4. Data for sample size estimation. We will document means and standard deviations on measures so that sample size can be estimated for the larger randomized clinical trial.