title: Intestinal adaptations to a combination of different diets with and without endurance exercise.
abstract: BACKGROUND
  Endurance athletes search for diet regimens that will improve performance and decrease gastrointestinal disturbances during training and events. Although the intestine can adapt to changes in the amount and composition of dietary inputs, the responses to the combination of endurance exercise and diet are poorly understood.
  
  
  METHODS
  We evaluated small intestinal dimensions and mucosal architecture and calculated the capacities of the entire small intestine to digest maltose and maltodextrin and absorb glucose in response to two different diet types; a western human diet and the Daniel Fast, a vegan style diet, and with moderate intensity endurance training or a no-exercise sedentary lifestyle for a 13 week period (n = 7 per group). The influences of diet and exercise, alone and in combination, were analyzed by analysis of variation.
  
  
  RESULTS
  Rats fed the western diet gained more weight (P < 0.05) due to more fat mass (P < 0.05), with a similar response for the sedentary compared with the exercised rats in each diet group (P < 0.05). The Daniel Fast rats had longer and heavier intestines with deeper crypts with villi that were wider (P < 0.05), but not taller. Despite increased energetic demands, the exercised rats had shorter and lighter intestines with shorter villi (P < 0.05). Yet, the percentage of mucosa did not differ among groups. Total small intestinal activities for maltase and α-glucoamylase, and capacities for glucose absorption were similar regardless of diet or exercise.
  
  
  CONCLUSIONS
  These findings indicate the structural responses of the small intestine to a vegan style diet are modified by exercise, but without altering the capacities of the brush border membrane to digest and absorb carbohydrates.
authors.affiliation: School of Health Studies, University of Memphis, 495 Zach Curlin Way, Memphis, TN USA.
authors.forename: Janice L
authors.initials: JL
authors.lastname: Daniels
authors.affiliation: School of Health Studies, University of Memphis, 495 Zach Curlin Way, Memphis, TN USA.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Bloomer
authors.affiliation: School of Health Studies, University of Memphis, 495 Zach Curlin Way, Memphis, TN USA.
authors.forename: Marie
authors.initials: M
authors.lastname: van der Merwe
authors.affiliation: School of Health Studies, University of Memphis, 495 Zach Curlin Way, Memphis, TN USA.
authors.forename: Samantha L
authors.initials: SL
authors.lastname: Davis
authors.affiliation: School of Health Studies, University of Memphis, 495 Zach Curlin Way, Memphis, TN USA.
authors.forename: Karyl K
authors.initials: KK
authors.lastname: Buddington
authors.affiliation: School of Health Studies, University of Memphis, 495 Zach Curlin Way, Memphis, TN USA.
authors.forename: Randal K
authors.initials: RK
authors.lastname: Buddington
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D004032:Diet; D000067269:Diet, Vegan; D066273:Diet, Western; D004063:Digestion; D005947:Glucose / Q000378:metabolism; D007421:Intestine, Small / Q000033:anatomy & histology / Q000502:physiology*; D008297:Male; D008320:Maltose / Q000378:metabolism; D008871:Microvilli / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology*; D005082:Physical Exertion; D011134:Polysaccharides / Q000378:metabolism; D051381:Rats; D020318:Rats, Long-Evans; D057185:Sedentary Behavior; D015430:Weight Gain
chemical_list: D011134:Polysaccharides; D008320:Maltose; C008315:maltodextrin; D005947:Glucose
keywords: Endurance training; Gastrointestinal; Vegan