Supplements Studied for Digestion & Gut Health: What the Evidence Shows

Healthy digestion depends on an intact intestinal barrier, a balanced gut microbiome, and comfortable gastrointestinal motility. Probiotics have been studied for digestive symptoms mainly in people with irritable bowel syndrome, where a 2018 meta-analysis found some strains appeared promising but could not draw definitive conclusions; that research does not establish a digestive benefit for people without a diagnosed bowel condition. L-glutamine is studied for its role in the intestinal lining, though a 2024 meta-analysis found no consistent effect on intestinal permeability. FormulaForge ranks every ingredient by the bioavailability of its available forms.

Updated 2026 · Reviewed by Dr. Brennan Commerford, D.C.

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Frequently Asked Questions

Which supplements have been studied for digestion and gut health?

L-Glutamine and probiotic strains (such as Lactobacillus and Bifidobacterium species) are among the most studied ingredients for digestion and gut function, but the studies cited on this page do not establish a digestive benefit for healthy people: glutamine did not significantly change intestinal permeability overall, and the probiotic trials enrolled people with irritable bowel syndrome. These supplements are not intended to diagnose, treat, cure, or prevent IBS, IBD, or any digestive disease. Consult a qualified healthcare provider for persistent gastrointestinal symptoms.

Does L-glutamine support gut barrier function?

L-Glutamine is the primary fuel source for the cells lining the intestine — a mechanism, not a demonstrated benefit — which is why it is studied in relation to intestinal barrier integrity. A 2024 systematic review and meta-analysis of 10 randomized, placebo-controlled trials (352 participants, many with existing health conditions; PMID 39397201) found that, overall, glutamine supplementation did not significantly change intestinal permeability. These are structure/function observations — L-glutamine is not a treatment for any condition.

Do probiotics support digestive comfort?

Probiotics are live beneficial microorganisms studied for supporting a balanced gut microbiome and digestive comfort. A 2018 systematic review and meta-analysis of randomized trials in people with irritable bowel syndrome (Ford et al.; PMID 30294792) found some probiotic combinations and strains appeared promising, but the authors could not draw definitive conclusions. Because these trials enrolled people with a diagnosed bowel condition, they do not establish a digestive benefit for people without one. These are structure/function claims; effects are strain-specific.