Adjusting a nutrient database to improve calculation of percent calories from macronutrients

Abstract

The sum of percent calories from protein, fat, carbohydrate, and alcohol did not always total 100% for dietary recalls or food records entered into the Nutrition Data System for Research (NDSR) 2007 and earlier versions of this software. This occurred because the calorie content of individual foods in the software's food and nutrient database were based on values calculated using either specific or general Atwater factors. Thus, daily total calorie intake estimates were based on calorie data derived from two different methods. In contrast, only general Atwater factors were applied when calculating the number of calories derived from each macronutrient in a daily diet. Two solutions to the macronutrient calculation problem just described were identified and evaluated. One approach was to create total daily calorie intake estimates based on general factors only. Using this approach, the same method to estimate energy is applied for both total calories and calories from each macronutrient calculation, thus ensuring that the sum of percent calories from each macronutrient totals 100%. The other solution was to incorporate energy factors specific to each core food into the NDSR nutrient database. Using these factors, calories contributed by each macronutrient are calculated for each food, and the calories/macronutrient summed for a daily total. The total calories/macronutrient divided by total calories per day × 100 provides the daily percent of calories from each energy macronutrient. The latter approach is preferable for a number of reasons. Most notably, we believe this approach will yield more accurate percent calories from macronutrient estimates, especially for diets rich in foods for which the general factors sub-optimally estimate energy composition. Thus, we opted to utilize this approach so that the sum of percent calories from macronutrients will total 100% for dietary recalls or food records entered into NDSR 2008 and subsequent versions of this software. The approaches to improving calculation of percent energy from individual macronutrients just described may be useful to others in maintaining databases that rely on energy composition information derived from varying methods.