. Author manuscript; available in PMC: 2020 Aug 1.

Published in final edited form as: Gut. 2019 May 10;68(8):1516–1526. doi: 10.1136/gutjnl-2019-318427

Table 2.

Summary of the literature on conditions that result in stress to the intestinal barrier, with documented effects on intestinal permeability or biochemical evidence of mucosal damage, and restoration with a dietary, non-pharmacological intervention

Barrier stressor; Clinical scenario	Specific Study	Effects on Barrier Function		Dietary Intervention and Its Effects	Reference #
Barrier stressor; Clinical scenario	Specific Study	Intestinal permeability	Mucosal Damage	Dietary Intervention and Its Effects	Reference #
Endurance exercise Marathon runners with fecal occult blood or bloody diarrhea	Biking challenge	Urine iohexol (MW 821Da) ↑	Serum I-FABP ↑, zonulin ↓		70
	Running challenge	LRR ↑ and correlated with core temperature (e.g. >39^°C)	ND		71
	Biking challenge	LRR ↑	Serum I-FABP ↑	Citrulline (vs alanine) reversed ↑serum I-FABP and gastric hypoperfusion without effect on LRR	72
	Biking challenge	ND	Serum I-FABP ↑	Sucrose (vs. nitrate) reversed ↑ serum I-FABP no Δ gastric hypoperfusion	73
	7 runners, 2 boxers, 3 rugby	LRR ↑	ND	Nurticeutical colostrum vs. placebo reduced LRR ↑ and apoptosis of cell lines in vitro	74
NSAID enteropathy: NSAIDs cause small bowel ulcers and inflammation	Diverse NSAIDs e.g. indomethacin	⁵¹CrEDTA, saccharides	ND		75–77
	Indomethacin	LRR ↑	ND	Zinc carnosine (vs. placebo) reduced LRR and increased HT29 cell proliferation (vs. ZnSO4)	78
	Aspirin	increased colon permeability: urine SLR and sucralose	ND	Bifidobacterium BB-12 and adolescentis (IVS-1) and galacto-oligosaccharide prebiotic reduce colon permeability	79
Pregnancy with or without obesity		Increased serum zonulin and increased serum LPS, associated with metabolic risk markers	ND		80
		High serum zonulin	ND	n-3 PUFAs, fiber, and a range of vitamins and minerals: reduced high serum zonulin; greater richness of gut microbiota	81
		No effects on serum zonulin or LPS	ND	Probiotics and/or LC-PUFA	82

Da=dalton; I-FABP=intestinal fatty-acid binding protein; LC-PUFA=long chain polyunsaturated fatty acids; LPS=lipopolysaccharide; LRR=lactulose-rhamnose ratio; ND=not determined; NSAIDs=nonsteroidal anti-inflammatory drugs; PUFA=polyunsaturated fatty acids; SLR=sucralose to lactulose ratio