Protexin Gut Balancer review: a simple, low-dose daily gut balancer

Protexin Gut Balancer is one of the most familiar tubs in UK feed rooms, sold as an everyday probiotic and prebiotic powder for horses and ponies. This is a desk review: we have not fed, tested or trialled the product, and everything below is based on the manufacturer's published product information, checked on 11 November 2026, alongside the wider research on its ingredients. Formulations and feeding rates can change, so treat the label on your own tub as the final word.

What it is

Protexin describes Gut Balancer as an everyday probiotic and prebiotic powder designed to support a healthy microbiota, digestive efficiency and general wellbeing. It is made by ADM Protexin and sold in 400g, 700g, 3.5kg and 7kg sizes. The product page says it is dandelion flavoured and intended for daily use, and the manufacturer's FAQ states it can be given long term, for the life of the horse where necessary.

It is a focused gut balancer rather than an all-round supplement. No vitamins, minerals or amino acids are declared, so it is designed to sit alongside a balanced diet rather than complete one. That simplicity is part of its appeal: there is little to double up on if your horse already has a feed balancer.

Declared key ingredients

The composition is listed as alfalfa meal, Preplex prebiotic (fructo-oligosaccharide) and brewers' yeast. The additives are the live yeast Saccharomyces cerevisiae CNCM I-4407 (4b1702) at 1 x 10 to the power of 12 CFU per kg, which Protexin also expresses as 1 x 10 to the power of 9 CFU per gram, and acacia (gum arabic) listed as a technological additive within Preplex.

Live yeast (Saccharomyces cerevisiae)

This is the probiotic element. Live yeasts are thought to act mainly in the hindgut, where they appear to support the fibre-digesting bacteria and help stabilise conditions when starch escapes digestion in the small intestine. At the declared count, a 10g daily serving supplies roughly 10 billion CFU. That figure is our arithmetic from the label, and CFU counts are not directly comparable between different yeast strains.

Fructo-oligosaccharides and gum arabic

Fructo-oligosaccharides (FOS) are short-chain carbohydrates that the horse cannot digest itself but gut microbes can ferment, which is why they are used as prebiotics. Gum arabic is a fermentable plant fibre. Protexin calls the combination its dual-source Preplex prebiotic. The page does not state how much FOS or gum arabic each serving provides.

Brewers' yeast and alfalfa meal

Brewers' yeast is an inactivated yeast, commonly included for palatability and as a source of yeast components and B vitamins. Alfalfa meal forms the base of the powder, which is worth knowing if your horse is on an alfalfa-free diet for any reason.

What the research says about these ingredients

The product page describes Gut Balancer as scientifically backed, but it does not cite a published feeding trial of this product, so we have looked at the wider evidence on its ingredient types. In a French study, horses given a different strain of Saccharomyces cerevisiae at 10g a day showed improved digestibility of the fibre fraction known as ADF on both high-fibre and high-starch diets (Jouany and colleagues, 2008). A follow-up found increased activity of several fibre-degrading enzymes in the hindgut of supplemented horses.

Not every study agrees. A Leipzig trial in healthy horses found no change in fibre digestion or fermentation profile with yeast supplementation, and very little yeast was recovered in the faeces (Mackenthun and colleagues, 2013). A widely cited review concluded that peer-reviewed evidence behind commercial equine probiotics is limited and that quality control of over-the-counter products is not tightly regulated (Schoster and colleagues, 2014).

On prebiotics, one laboratory study exposed samples of equine stomach lining to butyric acid at concentrations associated with FOS feeding and recorded changes to the tissue, suggesting FOS use deserves some thought in horses at risk of gastric ulcers (Cehak and colleagues, 2019). It was a tissue study, not a feeding trial, and it did not test this product. A balanced reading is that live yeast has a plausible mechanism and some supportive data, while the size of any benefit in an individual horse is uncertain. Our guide to equine probiotics covers this in more depth.

How it is fed

Protexin's directions are 10g (one level measure) added to the daily feed for normal use, and 20g (two level measures) for stress use. The FAQ says that if you mix the powder with water it should be fed as soon as possible afterwards, which makes sense for a live yeast product. It can be given during weaning and to weaned foals, according to the manufacturer.

Protexin also states that Gut Balancer can be fed alongside its Gut Sponge product, and suggests giving them at opposite ends of the day. For general advice on timing, storage and introducing a new supplement, see how to feed a probiotic.

Who it may suit

Gut Balancer is a sensible option for owners who want a straightforward, low-volume gut supplement without added vitamins and minerals. The small serving makes it easy to add to a handful of chaff, and the manufacturer specifically mentions picky eaters. It may also appeal to owners managing times of change, such as travel, competition, a move of yard or a shift between winter and spring grazing, where the stress rate gives a simple way to step up for a short period. Readers with horses on the move may find our page on travel and competition useful.

Limitations

• No product-specific trial is cited on the product page, so claims rest on ingredient-level research.
• The amounts of FOS and gum arabic per serving are not stated.
• The alfalfa meal base will not suit every feeding plan.
• It contains no vitamins or minerals, so it does nothing to balance a forage-only diet.
• No gut supplement can make up for too little forage, sudden feed changes or high-starch meals.

Things to check before choosing it

BETA NOPS and competition rules

The product page states that ADM Protexin is a member of BETA and NOPS accredited. The BETA NOPS scheme is designed to reduce the risk of naturally occurring prohibited substances in feed, and BETA describes it as a company scheme. Accreditation reduces risk rather than removing it, so always check your governing body's rules before competing.

Cereals and sugar

No cereal grains appear in the composition. FOS is a carbohydrate, but it is present in a low-inclusion powder, and the page does not publish a sugar or starch figure. If your horse has a sugar or starch restriction, ask the manufacturer for the full analysis.

Cost per day

We do not quote prices because they change. To compare value, divide the price of the tub by its weight in grams, then multiply by the daily amount. At 10g a day, a 700g tub lasts 70 days, or 35 days at the 20g stress rate. Larger tubs usually work out cheaper per gram.

Our verdict

Protexin Gut Balancer is a clear, uncomplicated product: one declared live yeast strain, a prebiotic blend and a small daily dose, from a company that states it holds NOPS accreditation. The research on live yeast in horses gives a reasonable rationale but not a guarantee, and the page does not cite a trial of the product itself. For owners who want a simple daily gut balancer alongside a well-balanced, forage-first diet, it is a reasonable shortlist candidate. Compare it with the alternatives in our UK horse probiotics comparison.