Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/1998
Publication Date: N/A
Interpretive Summary: Americans are eating a much greater variety of foods. Recently there has been an increased emphasis on accurate labeling of the nutritional content of these food. However, much of the labeling information is based on equations derived 50 years ago. Today's food supply is much different than 50 years ago and new methods need to be developed to accurately describe the nutritional value of foods. We know the caloric content of food is directly related to the proportion of fat, protein and carbohydrate in the food and the availability of these fractions. Other factors which have been shown to influence the calorie content of foods are the amount of dietary fiber and the type of fat. In this study we determined the energy value of two sources of dietary fat, beef fat and corn oil. In addition, we measured the extent to which dietary fiber interacted with these fats to affect the energy content of the diet. In this study, dietary fiber reduced the availability of both beef fat and corn oil thereby reducing th energy content of the diet. Benefit: From these observations we derived a new formula for calculating the energy value of diets which vary in fat and fiber content. These results will be of interest to nutritionist and to the meat industry.
Technical Abstract: Twelve individuals (6 male, 6 female) participated in three, two-week, controlled feeding periods. Digestibility and thermic effect of feeding (TEF) of either beef tallow (BT), corn oil (CO) or carbohydrate (CHO), added to the diet was determined on each individual. A base diet was formulated to contain 11% fat, 14% protein and the balance carbohydrate. From this base diet total dietary fiber content of these diets was increased by substituting high fiber items for low-fiber items. The volunteers consumed the base diet at a level approximately 75% of the energy intake necessary to maintain weight. The energy deficit was made up by the addition of BT, CO or CHO (sweetened beverages). This resulted in 6 treatment combinations; high-fiber + BT, low-fiber + BT; high-fiber + CO, low-fiber + CO, high-fiber + CHO, low-fiber + CHO. The digestibility of the CO and BT and CHO was 99.6, 99.8 and 100% respectively and was not significantly different between the fiber levels. The protein, fat and carbohydrate digestibility of the base diet were significantly different between the fiber levels. The digestibility (high-fiber/low-fiber) averaged 82 and 90% for protein and 96 and 98% for fat. After adjusting for total dietary fiber (TDF) the carbohydrate digestibility averaged 96% and was not different between fiber levels. The TEF was not different between fat sources or when compared to CHO. The energy content of the diet was found to be empirically represented by ME = 1.01 * intake energy (kJ) - 45 kJ * TDF (g).