Energy values of unavailable carbohydrate and diets: an inquiry and analysis.

To determine digestible-energy values (DEVs) for unavailable carbohydrate (UC), an analysis was made of published data on 29 human diets with UC from several sources and intakes ranging from 4 to 93 g/d. A distinction was made between apparent DEVs, derived from UC intake and fecal loss, and partial DEVs, derived from energy intake and fecal loss. By use of a proposed calculation, partial DEVs ranged from -20 to +10 kJ/g (-4.8 to +2.4 kcal/g) in different diets; all values were below the corresponding apparent DEVs. Factors explaining this range, including analytical problems, are considered. Rather than finding discrepancies, both the partial DEVs and the energy available from the whole diet were found to be related to the apparent digestibility of UC (r = 0.88), the proportion of the diet estimated as UC (r = 0.73), and both combined (r = 0.98). Several food-energy evaluation systems are also assessed for accuracy and the implications of these observations for food-energy evaluation are discussed.