The “leaky gut stack”: colostrum, zinc carnosine, aloe and co.

Healthy state

Forums and shops usually recommend a whole bundle against “leaky gut”: glutamine, colostrum Colostrum The first milk after birth, rich in antibodies and growth factors. As a supplement it usually comes from cows. , zinc carnosine, zinc, collagen or bone broth, aloe vera, slippery elm or marshmallow root, quercetin, curcumin and butyrate Butyrate A short-chain fatty acid and the main energy source for the cells of the colon wall. It strengthens the barrier and dampens inflammation. More in the chapter “Butyrate and other short-chain fatty acids”. Each is supposed to seal or soothe the gut wall at a different point. What the gut barrier is and what is known about glutamine is covered in the chapter on the gut barrier, butyrate in the chapter on short-chain fatty acids Short-chain fatty acids Acids such as acetate, propionate and butyrate that gut bacteria make from fibre. They nourish the gut wall and act throughout the body. More in the chapter “Butyrate and other short-chain fatty acids”. Experts stress that a separate “leaky gut syndrome” has neither a recognised diagnosis nor a reliable test.

Colostrum is a cow's first milk after calving, rich in antibodies (mainly IgG), lactoferrin and growth factors. In a small randomised trial Randomised trial A study in which chance decides who gets the treatment and who does not, for comparison. This makes results particularly reliable. in 7 healthy men, the painkiller indomethacin tripled small-intestinal permeability, measured with a urine sugar test. When they also took colostrum, it did not rise significantly. In 15 people who had been taking painkillers for a long time, colostrum changed nothing.

Zinc carnosine combines zinc with the protein building block carnosine. In 10 healthy people it likewise prevented the rise in permeability caused by indomethacin. In 8 volunteers whose body temperature rose by 2 degrees during hard exercise, permeability tripled; zinc carnosine or colostrum taken for 14 days reduced this rise by about 70 percent. A systematic review in sport found mostly favourable lab values for colostrum and glutamine, but a 2025 meta-analysis Meta-analysis An analysis that combines the results of several studies. It is only as good as the studies it includes. found no reliable effect of such supplements on gut symptoms during exercise.

The lining needs zinc itself to renew. In 12 people with Crohn's disease in a quiet phase and increased permeability, high-dose zinc for 8 weeks normalised the readings, though without a comparison group.

Aloe vera (the inner leaf gel) was compared with placebo Placebo A dummy treatment without an active ingredient. Comparing with it shows how much a remedy achieves beyond expectation and chance. in three small IBS Irritable bowel syndrome Recurring abdominal pain linked to bowel movements, without tests finding another cause. Today it is understood as a disorder of gut–brain interaction. More in the chapter “The gut-brain axis” trials. Two analyses from 2018 and 2020 saw a benefit, a newer one from 2026 no longer a reliable one. Curcumin from turmeric is best studied in ulcerative colitis: added to the standard drug mesalamine, 14 of 26 people on curcumin reached remission after four weeks in a 50-person trial, none on placebo. That concerns an inflammatory disease, not “leaky gut”.

For collagen, gelatin and bone broth there are hardly any human data. A 2025 review infers a benefit from the building blocks (glycine, proline, glutamine, minerals), not from studies of broth. The only study found on collagen and digestion was open-label, without a comparison group and used a branded product: of 40 women, 14 completed the eight weeks, and 13 of them reported less bloating. The manufacturer was involved: one co-author works there, and the consultancy of another was paid by it. Slippery elm and marshmallow contain mucilage, quercetin is a plant pigment; for all three there are lab experiments but no controlled studies in the human gut.

Disrupted state: causes and effects

Many people start several products at once, change their diet as well, and then feel better or worse. Which product did what cannot be told this way. Symptoms also fluctuate on their own, and the placebo effect in IBS is large. We found no published surveys on such combinations; in a consumer survey, barely a third even knew collagen as a digestive aid.

Zinc in the long run: a lot of zinc blocks copper absorption. Copper deficiency can cause anaemia, too few white blood cells and nerve damage with unsteady gait. The European Food Safety Authority (EFSA) sets the tolerable upper intake for adults at 25 mg of zinc per day, all sources combined. Combining zinc, zinc carnosine and a multivitamin easily exceeds it.

Not all aloe is the same. The gel from the inner leaf is different from the juice of the leaf skin, which contains anthranoids such as aloin and aloe-emodin. EFSA considers these substances potentially genotoxic and carcinogenic and could not name a safe daily amount; a whole-leaf extract caused cancer in animal studies. In a market survey in Italy, a third of herbal laxative and aloe products contained measurable amounts, most of all solid supplements; aloe drinks were mostly below the limit.

Curcumin: rare cases of liver injury have been described, usually after one to four months of use, and they mostly heal after stopping. Isolated cases of acute liver failure have occurred. Curcumin can also affect blood clotting, which matters together with anticoagulants.

Colostrum is a dairy product, and quality varies widely: 20 commercial products differed up to six-fold in biological activity in lab tests, and heating lowered it markedly. The concern that colostrum raises the growth hormone IGF-1 in the blood, on the other hand, was not confirmed in studies.

Bone broth: a small measurement found several times more lead in chicken bone broth than in the water it was cooked in, though only a few micrograms per litre in absolute terms. No reason to worry about a soup, but an argument against litres of broth for months.

Common to all: in many countries, dietary supplements are not tested for efficacy like medicines. A “leaky gut” label says nothing about whether a product will do anything for you. And treating symptoms with a stack sometimes postpones testing for coeliac disease Coeliac disease An autoimmune disease in which gluten damages the lining of the small intestine. It is diagnosed with a blood test and usually a biopsy while you are still eating gluten. More in the chapter “Lactose, fructose, gluten: making sense of intolerances”, inflammatory bowel disease Inflammatory bowel disease Umbrella term for Crohn’s disease and ulcerative colitis: long-term, relapsing inflammation of the gut that needs medical treatment. More in the chapter “Immune system and inflammation” or other causes.