Glutamine Supplementation and Intestinal Secretory IgA

Clinical Guidelines and Evidence

The European Society for Clinical Nutrition and Metabolism (ESPEN) states that there is insufficient evidence to recommend glutamine supplementation in clinical practice for cancer patients undergoing chemotherapy, radiotherapy, or targeted therapy 1, 2
The evidence for glutamine supplementation is heterogeneous, with some small studies showing benefits while larger, well-controlled trials show no effect, leading to concerns about its potential to fuel cancer cell metabolism 3, 1
Parenteral glutamine (0.5 g/kg/day) may be considered only in patients requiring exclusive parenteral nutrition who cannot be fed adequately enterally, although the recommendation is weak due to mixed evidence from RCTs 4, 6
High-dose glutamine is contraindicated in critically ill patients with organ dysfunction, as it has been associated with increased mortality 7
The clinical significance of increased stool sIgA as a standalone outcome is uncertain, and guidelines prioritize morbidity, mortality, and quality of life outcomes 3, 1
In inflammatory bowel disease, a systematic review of seven studies found no effect of glutamine (oral, enteral, or parenteral) on disease course, intestinal permeability, or inflammatory markers 8

Glutamine supplementation has not been shown to translate into meaningful clinical benefits that would justify routine supplementation, despite its biological effect on intestinal sIgA production 3, 1, 2
Safety concerns in specific populations (critically ill with organ dysfunction, potential cancer cell fueling) limit enthusiasm for widespread use 3, 7