Dietary adherence to whole grain and refined grain rich diets in a randomized controlled trial
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Dietary adherence is the degree to which participants follow prescribed dietary protocol. Without measuring adherence, it is not possible to validly measure the effect of the intervention. Assessing adherence allows the investigator to better determine whether the results are due to the diet itself. The overall goal of the analyses presented in this thesis was to assess if dietary adherence was higher on a whole grain versus refined grain provided food protocol with specific prescription for calorie consumption. Eighty-two men and women between the ages of 40-65 were assigned to either a refined or whole grain feeding protocol, using a 3-day rotating menu for 6 weeks. Daily food logs were used to assess adherence to the prescribed diets and calculate total energy consumed and macronutrient content. The first objective was to determine the caloric and macronutrient content of the assigned diets, and to compare whether the reported nutrient content was the same as the provided nutrient content. Overall, the median whole grain group consumption was 45.0 kcal per day more than they were assigned to, and the median refined grain group consumption was 10.5 kcal per day less than assignment. The refined grain diet's macronutrient composition was 52.1% carbohydrate, 19.9% protein, and 28.1% fat, whereas the whole grain group's macronutrient composition was 54.4% carbohydrate, 18.0% protein, and 27.6% fat. Both diets were within the average daily macronutrient recommendations of 50-55% carbohydrate, 15-20% protein, and 25-30% fat. There was a statistically significant difference in the percentage of carbohydrate and protein between groups. The second objective was to determine if two different diets had any effect on deviation from the protocol. Overall, there was an 8.9 kcal/day difference in deviation between the two groups throughout the study. When stratifying by diet level, there was no consistent pattern of deviations from the assigned protocol. On the 2000 kcal diet, those in the refined grain group consumed 184.5 kcals/day more than those in the whole grain group. In contrast on the 2500 kcal diet, the whole grain group consumed 105.0 kcal/day more than the refined grain group, while on the 3000 kcal/day diet, those in the refined grain group consumed slightly more kcals/day on average (12.5kcal/day) than the whole grain group. The study found no consistent difference in caloric consumption between the whole and refined grain groups, as well as no consistent difference in deviations from the assigned diet protocol. These results imply that dietary adherence can be achieved in a provided food whole grains study.