Location: Food Components and Health LaboratoryTitle: The metabolizable energy of dietary resistant maltodextrin is variable and alters fecal microbiota composition in adult men) Author
Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/17/2014
Publication Date: 4/17/2014
Citation: Baer, D.J., Stote, K.S., Henderson, T.R., Paul, D.R., Okuma, K., Tagami, H., Kanahori, S., Gordon, D.T., Rumpler, W.V., Ukhanova, M., Culpepper, T., Wang, X., Mai, V. 2014. The metabolizable energy of dietary resistant maltodextrin is variable and alters fecal microbiota composition in adult men. Journal of Nutrition. 114:1023-1029. Interpretive Summary: Resistant maltodextrin (RM) is a soluble, nonviscous fiber that is resistant to digestion but fermentable by microorganisms in the large intestine. In order to properly label foods and understand the impact of RM on the energy value of foods that contain this fiber, it is necessary to determine its metabolizable (ME) and net (NE) energy values. These values were determined in fourteen healthy male subjects by combining data from nutrient balance and calorimetry studies. In addition, data on the effects of consuming resistant maltodextrin on bowel habits and protein, fat, and carbohydrate digestion were evaluated. A randomized controlled, double blind, crossover study was conducted. Each subject was assigned to a treatment sequence that consisted of three amounts of resistant maltodextrin as part of a controlled diet: 0 g/d resistant maltodexrtin + 50 g/d maltodextrin, 25 g/d resistant maltodextrin + 25 g/d maltodextrin, and 50 g/d resistant maltodextrin + 0 g/d maltodextrin. Subjects consumed their treatment divided into two daily doses, one consumed with breakfast and the other with dinner. After an appropriate adaptation period, urine and feces were collected during a 7-d period. Following the collection period, energy expenditure of each subject was measured in a room-sized calorimeter. Amounts of dry mass, energy, nitrogen, resistant maltodextrin, and total carbohydrate in the feces each increased with the increasing dose of resistant maltodextrin. Fat excretion did not differ among treatments. The measured metabolizable energy value of this fiber was 8.2 kJ (2 kcal)/g and 10.4 kJ (2.5 kcal)/g, and the net energy value of RM was -8.2 kJ (-2.0 kcal)/g and 2.0 kJ (0.5 kcal)/g, for the 25 g/d and 50 g/d doses, respectively. These results are important for the food manufacturing industry, especially companies interested in increasing fiber content of foods, regulatory agencies involved with food labeling, and health professionals and policy makers who provide recommendations concerning fiber consumption.
Technical Abstract: Resistant maltodextrin (RM) is a novel soluble, nonviscous dietary fiber. Its metabolizable energy (ME) and net energy (NE) values derived from nutrient balance studies are unknown, as is the effect of RM on fecal microbiota. A randomized, placebo-controlled, double-blind crossover study was conducted (n = 14 men) to determine the ME and NE of RM and its influence on fecal excretion of macronutrients and microbiota. Participants were assigned to a sequence consisting of 3 treatment periods [24 d each: 0 g/d RM + 50 g/d maltodextrin and 2 amounts of dietary RM (25 g/d RM + 25 g of maltodextrin/d and 50 g/d RM + 0 g/d maltodextrin)] and were provided all the foods they were to consume to maintain their body weight. After an adaptation period, excreta were collected during a 7-d period. After the collection period, 24-h energy expenditure was measured. Fluorescence in situ hybridization, quantitative polymerase chain reaction, and 454 titanium technology–based 16S rRNA sequencing were used to analyze fecal microbiota composition. Fecal amounts of energy (544, 662, 737 kJ/d), nitrogen (1.5, 1.8, 2.1 g/d), RM (0.3, 0.6, 1.2 g/d), and total carbohydrate (11.1, 14.2, 16.2 g/d) increased with increasing dose (0, 25, 50 g) of RM (P < 0.0001). Fat excretion did not differ among treatments. The ME value of RM was 8.2 and 10.4 kJ/g, and the NE value of RM was -8.2 and 2.0 kJ/g for the 25 and 50 g/d RM doses, respectively. Both doses of RM increased fecal wet weight (118, 148, 161 g/d; P < 0.0001) and fecal dry weight (26.5, 32.0, 35.8 g/d; P < 0.0001) compared with the maltodextrin placebo. Total counts of fecal bacteria increased by 12% for the 25 g/d RM dose (P = 0.17) and 18% for the 50 g/d RM dose (P = 0.019). RM intake was associated with statistically significant increases (P < 0.001) in various operational taxonomic units matching closest to ruminococcus, eubacterium, lachnospiraceae, bacteroides, holdemania, and faecalibacterium, implicating RM in their growth in the gut. Our findings provide empirical data important for food labeling regulations related to the energy value of RM and suggest that RM increases fecal bulk by enhancing the excretion of nitrogen and carbohydrate and the growth of specific microbial populations.