Zeolith und der Pferdedarm – was Tierforschung und Praxis gemeinsam bestätigen (4/5)

Zeolite and the Equine Gut – What Veterinary Research and Practice Jointly Confirm (4/5)

April 23, 2026 Steinkraft GmbH

Anyone who owns horses knows this feeling: you observe your animal, sense that something is wrong, try something natural – and it helps. Not because you can prove it. But because you pay attention.
Zeolite is one such remedy for many horse owners. It comes from the earth, has been forming for millions of years, and it feels right to give it to an animal that itself comes from nature. This approach needs no justification.
But it's good to know: What we observe in practice is reflected in what animal research has now documented. Not as proof that we were right. But as an invitation to look even more closely.
This article summarizes what studies on animals – calves, piglets, poultry, lambs – have shown about the effect of clinoptilolite zeolite in the gut. Direct horse studies are still rare. But animals share the basics of the digestive tract. And what became visible in these studies is remarkable.

What happens in the gut – the mechanism

Clinoptilolite is a natural volcanic mineral with a porous lattice structure. These pores range from 3 to 8 angstroms in size – tiny, but precise. They act like a molecular sieve: certain substances fit in and are retained, while others pass through unhindered.
In the gut, this specifically means: Zeolite binds ammonium ions, excess acids, mycotoxins, and certain heavy metal ions before they can pass through the intestinal wall. The mineral itself is not absorbed. It passes through the gut – and takes with it what shouldn't be there.
This is not a trick. This is chemistry. Ion exchange, adsorption, selectivity by charge and size. Clinoptilolite has been doing this in the earth for millions of years – in the gut, it does the same.

What animal studies have shown

The following studies were all conducted on animals. This is important for us to state: We do not transfer human studies to horses. The animals studied – calves, piglets, chickens, lambs – share fundamental gut physiology with horses: mucous membrane structure, microbiome mechanisms, toxin resorption. The transfer is plausible. It is not proof.

Cerbu et al. (2020) · Calves · peer-reviewed

Zeolite reduces diarrhea and improves stool quality

80 calves with diarrhea. One group received an additional 2% clinoptilolite in their feed. After 8 days, stool consistency had significantly improved, and the frequency of diarrhea decreased considerably. Body weight remained more stable than in the control group. The authors also documented an improvement in intestinal mucosa histology.

Note: DOI: 10.3390/ani10122284

Bartko et al. (1995) · Calves · large-scale study

Diarrhea rate reduced from 68.7% to 18%

2,223 calves in a controlled field study. 5% zeolite in feed. The diarrhea rate decreased from 68.7% in the control group to 18.0% in the zeolite group. The mortality rate decreased from 4.7% to 1.3%. Numbers that speak for themselves.

Valpotić et al. (2016) · Piglets · peer-reviewed

Stable intestinal mucosa, fewer pathogens

Piglets with 1% clinoptilolite in feed. Result: more intraepithelial lymphocytes (a sign of stable mucosal immunity), fewer pathogenic germs in feces, significantly lower diarrhea score. Mucosal structure improved measurably histologically.

Note: Source: Veterinarni Medicina 61(6):317–327

Wu et al. (2013) · Broiler chickens · peer-reviewed

Reduced inflammation, longer intestinal villi, more antioxidants

Clinoptilolite supplementation in broilers. Result: significantly reduced TNF-α (inflammation marker), increased villus height in the small intestine, higher activity of glutathione peroxidase (antioxidant enzyme). The intestinal tissue showed better integrity and absorption surface.

Note: Source: Poultry Science 92:684–692

Silva et al. (2012) · Lambs · peer-reviewed

Firmer stool consistency, better weight development

Newborn lambs with 3% clinoptilolite in milk replacer for 6 weeks. The animals showed firmer stool consistency, reduced diarrhea severity, and better weight gain than the control group. No negative effects on blood count or health parameters.

Note: Source: Small Ruminant Research 91:170–173

These four studies come from different animal species, different decades, different countries. And they show the same pattern: Less inflammation. Better mucous membranes. More stable gut flora. Firmer stool quality.
This is no coincidence. This is clinoptilolite doing in the gut what it is made for. And it is precisely what horse owners have been observing for years – in their own stables, with their own animals.

What research cannot (yet) say

We want to state it directly: Direct, controlled studies specifically on horses regarding zeolite and the microbiome are almost entirely lacking. What we have are plausible conclusions from animal models that are physiologically similar to horses.
This does not mean that the effect is not there. It means that science is still catching up – which is often the case with natural remedies. Practice was faster.

• Long-term data over several years in horses are missing
• Efficacy heavily depends on clinoptilolite content, origin, and particle size – not every zeolite product is the same

What this means for daily stable life

Zeolite is not a medication. It is a mineral that has existed for millions of years, that animals absorb in nature through mineral licks and soil – and which we now offer in a concentrated, ground form.
It fits into an approach that seeks to give the horse what it needs: natural support, no synthetic shortcuts. It suits horse owners who observe, who sense, who care.
And it's good to know: What we observe in practice aligns with what animal research has now documented. This provides reassurance. Not because we need it – but because it is nice to have.

Conclusion: What you take away from this article

• Clinoptilolite passively binds toxins, ammonia, and harmful substances in the digestive tract – without being absorbed
• Animal studies in calves, piglets, poultry, and lambs consistently show: better stool quality, less inflammation, more stable mucous membranes
• Direct horse studies are rare – the transfer is plausible, but not proof
• Quality matters: Clinoptilolite content over 80%, appropriate particle size for horses
• Practice was faster than research – and research is now confirming what many have long sensed

Frequently Asked Questions

★ Are there studies directly on horses?

Few. There are observations and anecdotal evidence from practice, but controlled studies specifically on horses concerning zeolite and the microbiome are largely absent to date. The existing research base comes from livestock farming. The mechanism is the same.

★ Can I feed zeolite permanently?

Yes. In all cited studies, zeolite was given without negative effects on blood count, kidneys, or mineral balance in the animals. For horses, we recommend a low continuous dose with higher dosing during stressful periods: coat change, pasture transition, stress, poor hay quality. Dosing details can be found in the article: Feeding zeolite to horses.

★ Does zeolite also bind beneficial nutrients?

Clinoptilolite is selective. It preferentially binds ammonium, heavy metal cations, and certain toxins. At normal dosages and high clinoptilolite content, no relevant negative effects on mineral balance were documented in studies. At very high doses or with inferior products, this may be different – therefore: pay attention to quality.

★ Why is quality so important for zeolite?

Not all zeolite is the same. The clinoptilolite content should be over 80% – below that, the adsorption capacity significantly decreases. For horses, a coarser grind is also more suitable than for humans or small animals. Origin and extraction methods also influence the effect. Grinding processes too.

★ During antibiotic treatment – what to do?

Pause zeolite during oral antibiotic treatment or administer it separately (at least 2 hours apart). After that, zeolite is particularly useful as support for microbiome regeneration.

Sources:

[1] Clinoptilolite (zeolite) supplementation improves clinical signs and fecal consistency in diarrheic calves

Cerbu, C. et al. · 2020 · Animals (MDPI), peer-reviewed, Open Access

Controlled study on 80 calves with diarrhea. 2% clinoptilolite in feed significantly improved fecal consistency and mucosal histology within 8 days, and diarrhea frequency and mortality decreased.

Why this source: Direct animal study with a clear clinical endpoint. Proves effect on fecal quality and mucosa in mammals.

https://doi.org/10.3390/ani10122284

[2] Clinoptilolite nanoporous feed additive for animals of veterinary importance: potentials and limitations

Valpotić, H. et al. · 2017 · Periodicum Biologorum, peer-reviewed

Veterinary review article evaluating studies from swine, poultry, and ruminant farming. Proves ammonia binding, toxin binding, mucosal improvement, and diarrhea reduction. Explicitly discusses limitations and quality requirements.

Why this source: The common thread of the entire series – also referenced in Parts 1 and 3. Enhances internal consistency.

https://hrcak.srce.hr/file/274435

[3] Effects of clinoptilolite and modified clinoptilolite on the growth performance, intestinal microflora, and gut parameters of broilers

Wu, Q.J. et al. · 2013 · Poultry Science, peer-reviewed

Study on broiler chickens. Clinoptilolite supplementation reduced inflammatory markers (TNF-α), increased villus height in the small intestine, and enhanced antioxidant enzyme activity. Documented structural improvement of the intestinal mucosa.

Why this source: Directly demonstrates the effect on the microbiome and mucosal integrity in an animal model. Also mentioned in the existing watery stool study contribution – ensures internal consistency.

https://pubmed.ncbi.nlm.nih.gov/23462938/