At a glance
- Product
- Protexin Acid Ease
- Brand
- Protexin (ADM Protexin)
- Type
- Gastric support supplement
- Format
- Powder
Our verdict: A well-specified gastric support powder with declared amounts of calcium carbonate, pectin, kaolin and L-threonine, plus a live yeast, and stated NOPS accreditation. It is dietary support rather than treatment, and the high calcium contribution should be factored into the whole diet.
May suit
- Horses with a vet-confirmed history of gastric problems, alongside veterinary treatment
- Horses in training or competition where owners want stomach support
- Owners wanting a supplement that can be fed with omeprazole
What we like
- Declared amounts for key buffering and lining-support ingredients
- Manufacturer states NOPS accreditation and FEI Clean Sport compliance
- Clear loading and maintenance rates
- Can be fed alongside omeprazole, according to Protexin
Things to consider
- Adds a large amount of calcium at the starting rate
- Small inconsistencies between description, FAQ and composition
- No product-specific trial cited on the product page
Key ingredients as declared
| Ingredient | Generally used for |
|---|---|
| Calcium carbonate (35%) | An antacid used to buffer stomach acid |
| Pectin (4.7%) | A gel-forming soluble fibre used to support the gut lining |
| Kaolin | A clay traditionally used to coat the gut |
| L-threonine | An amino acid used in the mucus that lines the gut |
| Saccharomyces cerevisiae CNCM I-4407 (live yeast) | Used to support fibre digestion in the hindgut |
Desk review based on the manufacturer’s published information, checked on 11 November 2026. We did not test or feed this product. How we review.
Protexin Acid Ease is a stomach-focused supplement from the same company that makes Protexin Gut Balancer. Where a gut balancer mainly targets the hindgut, Acid Ease is built around buffering agents and ingredients intended to support the gut lining. This is a desk review based on Protexin's published product information, checked on 11 November 2026, and on the wider research on gastric health. We have not fed or tested it.
What it is
Protexin describes Acid Ease as a concentrated, palatable nutritional supplement designed to support optimal digestive function in horses and weaned foals, formulated to target the challenges of excess acidity. It combines fibres and buffering agents with what the company calls a tribiotic formula of prebiotic, probiotic and postbiotic. It is sold in 1.5kg and 3kg tubs.
The product sits in the gastric supplement category. It is designed to support the stomach environment through diet, not to diagnose or treat gastric ulcers, and Protexin's FAQ confirms it can be given alongside a prescribed medicine such as omeprazole.
Declared key ingredients
The composition is listed as calcium carbonate (35%), alfalfa meal, inactivated yeast Pichia guilliermondii (CitriStim postbiotic, 5.0%), lignocellulose, pectin (4.7%), maltodextrin (Fibersol-2 prebiotic, 4.7%) and dicalcium phosphate (2.3%). Additives are the live yeast Saccharomyces cerevisiae CNCM I-4407 (4b1702), kaolin at 115,000mg per kg, L-threonine at 46,500mg per kg and a dandelion flavouring.
Calcium carbonate
Calcium carbonate is an antacid, used to neutralise acid on contact. At the starting rate of 100g a day, the 35% inclusion means about 35g of calcium carbonate daily, which is a substantial calcium contribution. That should be factored into the whole diet, particularly if you also feed a balancer. The product description mentions magnesium carbonate as well, but we could not see it in the published composition list, so check the label.
Pectin and kaolin
Pectin is a soluble fibre that forms a gel, and kaolin is a clay traditionally used to coat and soothe the gut. Protexin says these work with L-threonine to soothe and protect the gut lining.
L-threonine
Threonine is an amino acid and a major building block of the mucus proteins that line the gut, which is the usual reason for including it in gastric products.
Live yeast, CitriStim and Fibersol-2
The live yeast is the same strain declared in Protexin Gut Balancer. CitriStim is an inactivated yeast that Protexin labels a postbiotic, and Fibersol-2 is a resistant maltodextrin used as a prebiotic. The FAQ states that Acid Ease contains the same probiotic and prebiotics as Gut Balancer, but the composition names Fibersol-2 rather than Preplex, so ask Protexin if this matters to you. The live yeast count on the page appeared without its exponent when we checked, so read the count from the tub label.
What the research says
Equine gastric ulcer syndrome is now understood as two separate conditions, squamous and glandular gastric disease, with different causes and responses to treatment (Vokes and colleagues, 2023). That distinction matters, because a supplement that buffers acid may not address every form of the problem.
Research on supplements of this type is limited and mixed. One study of pectin, lecithin and antacid supplements found no effect on gastric fluid pH, but horses given the supplements had less severe squamous ulcers than controls after a period of feed deprivation (Woodward and colleagues, 2014). Those products contained lecithin, which Acid Ease does not declare, so the results do not transfer directly. We did not find a published trial of Acid Ease itself, or a controlled horse trial of CitriStim that we could cite.
How it is fed
Protexin's directions are 50g twice a day for the first month, then reduce by half for maintenance. One heaped measure of the enclosed scoop holds approximately 50g. If mixed with water, it should be fed as soon as possible afterwards. The manufacturer says it can be used long term at the maintenance level and is suitable for weaned foals. For general feeding practice, our probiotic feeding guide also applies to products with live yeast.
Who it may suit
Acid Ease may suit horses with a vet-confirmed history of gastric problems, as dietary support alongside the vet's treatment plan, or horses in training and competition where the owner wants to support the stomach environment. Protexin mentions horses prone to gastric sensitivities and those undergoing training stress. For the difference between this kind of product and a hindgut-focused one, see gut balancer vs gastric supplement.
It is a less natural fit for a horse with no history of stomach problems that simply needs general digestive support, where a lower-dose gut balancer is simpler and cheaper per day. It also makes sense to review management first. Long gaps without forage, large cereal meals and exercise on an empty stomach are all commonly discussed risk factors for gastric problems, and changing those habits costs nothing.
Limitations
- It cannot diagnose or treat ulcers, and buffering effects from antacids are short lived.
- The starting rate of 100g a day adds a significant amount of calcium.
- No product-specific trial is cited on the product page.
- There are small inconsistencies between the description, FAQ and composition list.
- It is one of the larger daily servings in this group.
Things to check before choosing it
BETA NOPS and competition rules
Protexin states that the 1.5kg and 3kg tubs are BETA NOPS accredited and compliant with FEI Clean Sport guidelines. That reduces risk but does not remove it, so check your governing body's rules. BETA also runs a separate feed assurance mark for feeds suitable for horses prone to gastric ulcer syndrome, which is useful when choosing the rest of the diet.
Cereals and sugar
No cereal grains are declared. Maltodextrin is listed, though Fibersol-2 is marketed as a resistant fibre. No sugar or starch analysis is published on the page. Feeding management, especially plenty of forage and limited starch, remains the foundation for stomach health.
Cost per day
Divide the tub price by its weight in grams and multiply by the daily amount. At 100g a day, a 1.5kg tub lasts 15 days during the first month, then about 30 days at the 50g maintenance rate. Budget for the higher first month.
Our verdict
Protexin Acid Ease is a well-specified gastric support supplement with declared amounts for its key buffering and lining-support ingredients, and it states NOPS accreditation. Its role is dietary support, ideally alongside veterinary diagnosis and good feeding management. Owners should account for the high calcium contribution and check the small label inconsistencies with the manufacturer. To see how it relates to hindgut products, read our UK horse probiotics comparison.