Best Supplements for Gut Health (Based on What We Actually Know)

Gut health supplements are a $7+ billion market, and roughly 80% of the claims on those products aren't backed by the kind of evidence most people assume exists. That's not to say nothing works. Some things do. But the gap between marketing and science in this category is enormous.

Your gut microbiome contains roughly 38 trillion microorganisms — bacteria, fungi, viruses, archaea. We've identified maybe a third of the species. We understand the function of far fewer. Anyone who tells you they can "optimize" your microbiome with a supplement is overselling what's currently possible.

That said, here's what we actually know works, what probably helps, and what's mostly hype.

Probiotics: The Strain Is Everything

Here's the most important thing about probiotics that most people get wrong: you can't just say "probiotics work" or "probiotics don't work." It's like saying "drugs work." Which drug? For what condition? At what dose?

Different probiotic strains do completely different things. Lactobacillus rhamnosus GG has no relationship to Lactobacillus acidophilus in terms of clinical effects. Lumping them together because they're both "Lactobacillus" is like saying aspirin and chemotherapy are interchangeable because they're both medicines.

Strains With Actual Evidence

Notice something? The evidence is almost always for specific conditions, not vague "gut health." A Cochrane review of 63 trials found solid evidence for probiotics in preventing antibiotic-associated diarrhea (NNT of 13, meaning you'd need to treat 13 people for one to benefit). But for general "digestive wellness"? The data gets thin fast.

The CFU Arms Race

Companies are locked in a colony count war. 10 billion. 50 billion. 100 billion. Now there are products boasting 300 billion CFU. It makes for great marketing, but higher numbers don't mean better results.

Bifidobacterium infantis 35624 showed benefit for IBS at just 1 billion CFU — significantly outperforming higher doses of the same strain in the original dose-finding study. LGG works well at 10-20 billion. More isn't more.

What actually matters: Is the strain research-backed? Is it alive at the time you take it (not just at manufacture)? Does it survive stomach acid? Those questions matter far more than whether you're getting 50 or 200 billion of an untested strain.

Prebiotics: Feeding What's Already There

Prebiotics take the opposite approach from probiotics. Instead of adding new microorganisms, you feed the ones already living in your gut. The concept is arguably more sound — you've got trillions of bacteria adapted to your specific gut environment, and giving them proper fuel makes more sense than parachuting in foreign strains and hoping they stick around.

The most researched prebiotics:

• Inulin: Found naturally in chicory root, garlic, onions. Selectively feeds Bifidobacteria. Typical supplement dose: 5-10 grams/day.
• FOS (fructooligosaccharides): Similar to inulin but shorter chain. Well-tolerated at 5-15 grams/day.
• GOS (galactooligosaccharides): Good evidence for increasing Bifidobacteria counts. Commonly found in legumes.
• Partially hydrolyzed guar gum (PHGG): A soluble fiber with decent evidence for IBS, particularly the constipation-predominant type. 5 grams/day is the standard dose.

One warning: if you're not used to fiber, start low. Going from 10 grams of daily fiber to 25 grams overnight will produce impressive amounts of gas. Ramp up by 3-5 grams per week.

Most people don't need a prebiotic supplement if they're eating enough vegetables, legumes, and whole grains. The supplement becomes useful when dietary fiber intake is consistently low — which, admittedly, applies to about 95% of Americans who don't meet the recommended 25-38 grams per day. — Suppi Research Team

L-Glutamine: Fuel for Your Gut Lining

L-glutamine is the most abundant amino acid in your bloodstream, and it's the primary energy source for enterocytes — the cells lining your intestinal wall. Your small intestine is the single biggest consumer of glutamine in your body.

The rationale for supplementation is straightforward: under stress (illness, intense exercise, post-surgery), glutamine demand exceeds supply. Your gut lining suffers, potentially becoming more permeable — what's loosely called "leaky gut."

What the Research Shows

In critically ill patients, glutamine supplementation (0.3-0.5 g/kg/day) reduces infectious complications and may reduce hospital mortality. A 2014 meta-analysis in Critical Care Medicine found a significant reduction in hospital mortality in surgical ICU patients receiving glutamine.

For healthy adults, the evidence is weaker but still interesting. A small 2012 study in Clinical Nutrition found that glutamine (0.5 g/kg body weight) reduced intestinal permeability caused by intense exercise. Athletes sometimes use 5-10 grams post-workout for gut recovery.

For IBS or general gut issues in otherwise healthy people? Honestly, the data is still preliminary. A 2019 randomized controlled trial in Gut found that glutamine (5 g three times daily) significantly reduced IBS symptoms in patients with post-infectious IBS and increased intestinal permeability. That's promising, but it's one trial in a specific subgroup.

Typical dose: 5-10 grams daily, often split into 2-3 doses. It's a powder that mixes easily into water and has virtually no taste.

Digestive Enzymes: Targeted, Not Universal

Your pancreas produces digestive enzymes — lipase for fats, protease for proteins, amylase for carbohydrates. Supplemental digestive enzymes are genuinely useful in two situations:

1. Pancreatic insufficiency: Chronic pancreatitis, cystic fibrosis, or post-pancreatic surgery. In these cases, prescription-strength enzymes (like pancrelipase) are medically necessary.
2. Specific food intolerances: Lactase for lactose intolerance actually works — it's one of the most straightforward supplement success stories. Alpha-galactosidase (Beano) helps with gas from beans and cruciferous vegetables. DPPIV enzymes may help some people with incidental gluten exposure (not a treatment for celiac disease).

Broad-spectrum digestive enzyme blends marketed for "improved digestion" in healthy people? There's almost no controlled evidence supporting that. If you have normal pancreatic function, adding extra enzymes is like pouring more laundry detergent into a washing machine that already has enough — you're not getting cleaner clothes.

One exception worth noting: as people age past 60-70, some decline in digestive enzyme production does occur. If an older adult experiences persistent bloating and incomplete digestion, a trial of enzymes is reasonable.

Zinc Carnosine: The Dark Horse

Zinc carnosine (also called zinc-L-carnosine or by the brand name PepZin GI) is a chelated compound of zinc and L-carnosine that was developed in Japan for gastric ulcer treatment. It's probably the least known supplement on this list, and it has some of the most interesting evidence.

The compound adheres to ulcer sites and damaged areas of the stomach lining. It doesn't just pass through — it concentrates where it's needed. A randomized double-blind study published in Gut found that zinc carnosine (37.5 mg twice daily) reduced small intestinal injury caused by indomethacin (an NSAID) by threefold compared to placebo.

Additional research shows:

• Reduced gastric inflammation in H. pylori-infected patients (as an adjunct to standard therapy)
• Protection against aspirin-induced gastric damage
• Stimulation of gut repair processes including cell migration and proliferation

The standard dose is 75 mg zinc carnosine twice daily (providing about 16 mg elemental zinc total). Side effects are minimal. It's well-tolerated and doesn't cause the nausea that high-dose zinc supplements can.

If you regularly take NSAIDs for pain and worry about your stomach lining, zinc carnosine is worth looking into.

What About Colostrum, Bone Broth, and Slippery Elm?

Quick takes on some popular options that didn't make the main list:

• Bovine colostrum: Contains immunoglobulins and growth factors. Some evidence for reducing NSAID-induced gut permeability. The research is limited but intriguing. Dose: 500-1000 mg daily.
• Bone broth: Tasty, contains glycine and gelatin, but no clinical trials demonstrating gut health benefits. The "heals the gut lining" claims are entirely theoretical.
• Slippery elm: Traditional demulcent (forms a soothing coating). Might help with reflux symptoms through a physical mechanism. Minimal clinical research.
• Butyrate supplements: Butyrate is the preferred fuel for colonocytes (colon cells). Oral supplementation may help, but most butyrate produced naturally comes from fiber fermentation in the colon. Eating more fiber achieves the same end more reliably.

A Realistic Gut Health Protocol

If you're starting from scratch and want to actually improve gut health with supplements, here's a sensible approach ranked by evidence strength:

1. Get fiber right first. This matters more than any supplement. Aim for 25-35 grams daily from diverse plant sources. Add a prebiotic supplement only if dietary fiber is consistently low.
2. Use specific probiotic strains for specific issues. Antibiotic course? LGG or S. boulardii during and for a week after. IBS? Try B. infantis 35624 for 4 weeks. Don't just grab the highest CFU count.
3. Consider L-glutamine if you have known gut permeability issues, post-infectious IBS, or you're an endurance athlete. 5 grams, 2-3 times daily.
4. Add zinc carnosine if you regularly use NSAIDs or have a history of gastric issues. 75 mg twice daily.
5. Use digestive enzymes only for diagnosed deficiencies or specific intolerances.

And honestly — sleep, stress management, and not eating like a raccoon in a dumpster probably matter more than any of these supplements. The gut-brain axis is real, and chronic stress actively degrades your gut barrier. No supplement fixes that.

1. Hempel S, et al. "Probiotics for the prevention and treatment of antibiotic-associated diarrhea." JAMA. 2012;307(18):1959-69.
2. Whorwell PJ, et al. "Efficacy of an encapsulated probiotic Bifidobacterium infantis 35624 in women with irritable bowel syndrome." Am J Gastroenterol. 2006;101(7):1581-90.
3. Zhou Q, et al. "Randomised placebo-controlled trial of dietary glutamine supplements for postinfectious irritable bowel syndrome." Gut. 2019;68(6):996-1002.
4. Mahmood A, et al. "Zinc carnosine, a health food supplement that stabilises small bowel integrity and stimulates gut repair processes." Gut. 2007;56(2):168-75.
5. Davison G, et al. "Zinc carnosine works with bovine colostrum in truncating heavy exercise-induced increase in gut permeability in healthy volunteers." Am J Clin Nutr. 2016;104(2):526-36.
6. Pugh JN, et al. "Glutamine supplementation reduces markers of intestinal permeability during running in the heat." Eur J Appl Physiol. 2017;117(12):2569-77.