Allulose is absorbed by the small intestine and excreted in the urine without being significantly metabolized. A study in 14 healthy adults consuming allulose at 5 to 20 g reported urinary excretion of allulose at 66-79% and low microbial fermentability of allulose in the large intestine . In another study, 8 healthy adults consumed 15 g unlabeled allulose with 776 nCi of 14C-allulose. Results showed that 86% of the radioactive dose was excreted in the urine, less than 3% excreted in the feces, and virtually no radioactivity was detected in expired air. Of the radioactivity in the urine, intact allulose was predominant (84%) with no other metabolites detected indicating that allulose is absorbed in the small intestine and excreted in the urine without undergoing significant metabolism .
Allulose produced a neglible amount of energy
The energy value of allulose is predicted to be 0.2 kcal/g, a negligible amount based on human studies. A study in healthy adults reported that allulose, absorbed in small intestine, was not metabolized into energy as neither carbohydrate energy expenditure (CEE) nor respiratory quotient (RQ) increased in three hours after ingestion of 0.35 g/kg body weight or 20 g allulose . A 0.9 to 1.6 kJ/g energy yield (0.2-0.4 kcal/g) was predicted based on low breath hydrogen excretion (due to low colonic fermentation) following intake of 5-20g allulose in the same study . Another study evaluating absorption, metabolism, and excretion showed no significant metabolism of allulose . Thus, the caloric value of allulose is likely negligible.
References Iida T, Hayashi N, Yamada T, Yoshikawa Y, Miyazato S, Kishimoto Y, Okuma K, Tokuda M, Izumori K. Failure of d-psicose absorbed in the small intestine to metabolize into energy and its low large intestinal fermentability in humans. Metabolism 2010; 59:206-214.  Williamson et al. A single dose microtracer study to determine the mass balance of orally administered, 14C-labeled sweetener in healthy adult men. FASEB J 2014; 28(1):LB450.