Combat-training increases intestinal permeability, immune activation and gastrointestinal symptoms in soldiers

Aliment Pharmacol Ther. 2013 Apr;37(8):799-809. doi: 10.1111/apt.12269. Epub 2013 Feb 24.


Background: Gastrointestinal (GI) symptoms are common in soldiers in combat or high-pressure operational situations and often lead to compromised performance. Underlying mechanisms are unclear, but neuroendocrine dysregulation, immune activation and increased intestinal permeability may be involved in stress-related GI dysfunction.

Aim: To study the effects of prolonged, intense, mixed psychological and physical stress on intestinal permeability, systemic inflammatory and stress markers in soldiers during high-intensity combat-training.

Methods: In 37 male army medical rapid response troops, GI symptoms, stress markers, segmental intestinal permeability using the 4-sugar test (sucrose, lactulose, mannitol and sucralose) and immune activation were assessed during the 4th week of an intense combat-training and a rest period.

Results: Combat-training elicited higher stress, anxiety and depression scores (all P < 0.01) as well as greater incidence and severity of GI symptoms [irritable bowel syndrome symptom severity score (IBS-SSS), P < 0.05] compared with rest. The IBS-SSS correlated with depression (r = 0.41, P < 0.01) and stress (r = 0.40, P < 0.01) ratings. Serum levels of cortisol, interleukin-6, and tumour necrosis factor-α, and segmental GI permeability increased during combat-training compared with rest (all P < 0.05). The lactulose:mannitol ratio was higher in soldiers with GI symptoms (IBS-SSS ≥75) during combat-training than those without (IBS-SSS <75) (P < 0.05).

Conclusions: Prolonged combat-training not only induces the expected increases in stress, anxiety and depression, but also GI symptoms, pro-inflammatory immune activation and increased intestinal permeability. Identification of subgroups of individuals at high-risk of GI compromise and of long-term deleterious effects of operational stress as well as the development of protective measures will be the focus of future studies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anxiety Disorders / etiology
  • Asians
  • Depressive Disorder / etiology
  • Gastrointestinal Diseases / etiology*
  • Gastrointestinal Diseases / immunology
  • Humans
  • Immune System / physiology*
  • Intestinal Mucosa / metabolism*
  • Male
  • Military Personnel*
  • Permeability
  • Physical Education and Training*
  • Prospective Studies
  • Regression Analysis
  • Singapore
  • Stress, Physiological*
  • Stress, Psychological*
  • Surveys and Questionnaires
  • Young Adult