An Alternative to Probiotics? The Benefits of Postbiotics in Pet Food Development

In recent years, as growing attention has been paid to pet health maintenance and improving the gut environment, postbiotics have emerged as a new alternative to probiotics. This article explains their characteristics, benefits, and potential applications in pet food.

The Long History of Fermented Foods in Human Culture

Humans have consumed fermented foods and beverages for thousands of years. There is even the well-known biblical story of Christ turning water into wine, a fermented drink.

Around the world, many different fermented foods have long been part of traditional food cultures, such as German sauerkraut, Korean kimchi, Russian kefir, Japanese miso, Norwegian rakfisk, and Indian pitha.

Nearly every human food culture includes fermented dairy products such as cheese, yogurt, and cottage cheese, which are still widely consumed today as nutritious foods.

Fermented foods have been widely accepted because of their excellent shelf life, nutritional value, and palatability. In addition, they are believed not only to support digestive health in humans, but also to help prevent type 2 diabetes and cardiovascular disease.

According to one research company’s survey of fermented foods, they contain high levels of live microorganisms, ranging from 10⁵ to 10⁹ CFU (colony-forming units) per gram of food.

Consumer awareness of the health benefits of fermented foods has also been increasing. A 2018 restaurant menu trend survey reported that the number of menu offerings featuring fermented foods had increased by 149%.

Expanding Use in Pet Food

Against this backdrop, the pet food industry has also begun to introduce new types of products using fermented ingredients. In the United States, one brand developed pet food made primarily from protein produced through koji fermentation.

This protein has been described as a “clean protein” and, because it is not animal-derived, it also offers sustainability advantages. In fact, it is said to require 90% fewer resources to produce compared with meat-based foods.

These types of products emphasize sustainability, but another major attraction of fermented foods lies in the health benefits associated with probiotics, or beneficial bacteria.

Probiotics are live microorganisms typically consumed through supplements or foods. They are believed to help suppress pathogenic bacteria in the gut, improve immune function, reduce the production of carcinogenic substances, inhibit tumor growth, and regulate bowel movements.

Probiotics Are Sensitive to Heat

Despite the growing interest in fermented foods and the benefits of probiotics, why are these ingredients not more actively used by mainstream pet food brands?

The reason is simple. The dominant product formats in pet food, such as extruded products and retort-processed foods like canned diets, are not suitable environments for probiotic survival. These processing methods and packaging conditions make it difficult for live microorganisms to remain viable.

That said, some heat-resistant strains can survive the manufacturing process. Even so, commonly used processing methods remain a major limitation when incorporating live bacteria into pet food.

Postbiotics: Effective Even Without Live Bacteria

The primary role of probiotics is to help balance the gut environment. In other words, it is the activity and fermentation of live microorganisms in the intestines that produce a variety of health benefits.

However, it is actually possible to deliver the benefits of fermentation to dogs and cats even without this fermentation taking place inside the gut. To understand this, it is first necessary to understand how probiotics exert positive effects on intestinal health.

The Natural Defense Functions of Microorganisms

We often focus on the harmful effects that pathogenic bacteria such as Salmonella can have on human and pet health, but beneficial microbes also exist. These bacteria possess natural defense mechanisms that help them survive in competition with other microbes, including the secretion of antimicrobial substances.

For example, Lactococcus lactis, a type of lactic acid bacterium, is known to secrete hydrogen peroxide, which has been shown to be effective against foodborne pathogens.

In addition, bacteria produce a variety of antimicrobial compounds to survive in harsh environments. One example is a group known as lantibiotics.

According to one study, about 20 unique compounds have been identified among lantibiotics, and because they act through multiple mechanisms, they are attracting interest as naturally derived antimicrobial agents.

Beyond lantibiotics, many other antimicrobial compounds also exist. Fermentation-derived ingredients containing such compounds are believed to have the ability to alter the composition of the gut microbiota.

Postbiotics: Beneficial Even When the Microbes Are No Longer Alive

As explained above, fermented foods do not necessarily need to contain live probiotic bacteria to produce positive changes in the gut. This idea led to the concept of postbiotics.

Postbiotics generally refer to beneficial metabolites produced by gut microbes from dietary components. Because they are more heat-stable, they make it possible to retain the benefits of fermentation even in pet food manufacturing processes where live bacteria would normally be destroyed.

Definition and Potential of Postbiotics

The term postbiotics is relatively new, and its definition has not yet been fully standardized. At present, however, it is generally understood to mean metabolites produced through probiotic activity that directly or indirectly provide beneficial effects to animals and humans.

Put more simply, postbiotics are beneficial compounds generated during the growth and activity of probiotics. In some cases, probiotic-derived cellular components themselves may also be included.

As discussed above, many of these substances have antimicrobial and immune-related functions, meaning they can produce health benefits even without live bacteria. In fact, some postbiotics are deliberately designed by destroying live bacteria and extracting their cellular components in order to enhance their effectiveness.

Types of Postbiotics

The health benefits of postbiotics come from the metabolites and microbial cellular components they contain. For this reason, many postbiotics do not refer to “live bacteria” themselves, but rather to the substances produced by those bacteria.

In fact, postbiotics are already being used to some extent in the pet food industry, although their functions and significance are not yet widely recognized. The postbiotics currently used include the following:

Type	Characteristics	Benefits	Raw Materials / Sources
Short-chain fatty acids (SCFAs)	Organic acid metabolites produced when beneficial bacteria ferment dietary fiber	Lower intestinal pH, suppress harmful bacteria, repair intestinal mucosa, anti-inflammatory effects, energy supply	Produced by fermenting prebiotics such as inulin and fructooligosaccharides with Bifidobacterium and butyrate-producing bacteria such as Clostridium butyricum
Inactivated microbial cells	Probiotic cells that have been killed by heat or other treatment	Immune activation (IgA, NK cells), gut flora modulation, anti-allergy effects	Lactobacillus spp., Bifidobacterium spp., Enterococcus faecalis and others (e.g. L-92, EC-12)
Cell wall components	Cell wall materials from inactivated microbes that stimulate PRRs	Immune activation and regulation, strengthened barrier function, reduced antigen response	Cell walls of Gram-positive bacteria such as lactic acid bacteria and bifidobacteria; yeast-derived beta-glucans, peptidoglycans, and lipoteichoic acid from Saccharomyces
Bacteriocins	Antimicrobial peptides produced by beneficial bacteria	Suppression of harmful bacteria, control of foodborne pathogens, normalization of gut microbiota	Produced by strains such as Lactococcus lactis (nisin) and Pediococcus acidilactici (pediocin)
Exopolysaccharides (EPS)	High-molecular-weight polysaccharides secreted by beneficial bacteria	Protection of intestinal mucosa, immune modulation, improved probiotic colonization	EPS-producing strains such as Lactobacillus rhamnosus GG and Bifidobacterium breve
Fermentation metabolites	Mixtures of organic acids, peptides, vitamins, and other compounds secreted during microbial culture	Antioxidant effects, anti-inflammatory activity, gut regulation, digestive support, immune support	Extracts from plant-derived lactic acid bacteria, acetic acid bacteria, natto bacteria, and others cultured using substrates such as rice bran, soy milk, and molasses
Microbially derived vitamins	Vitamins synthesized by beneficial bacteria	Support for bone, vascular, and nervous system health; metabolic support; improved skin and coat condition	Vitamin K2 (menaquinone) produced by bifidobacteria and butyrate-producing bacteria; B vitamins (B2, B6, B12) produced by lactic acid bacteria and yeasts
Yeast-derived components (e.g. brewer’s yeast)	Inactivated yeast, cell wall components, or metabolites	Immune activation, toxin binding, improved skin and coat health, nutritional support	Saccharomyces cerevisiae (brewer’s yeast), baker’s yeast-derived beta-glucans, mannan oligosaccharides (MOS), nucleotides, and B vitamins

These postbiotics are already used in some pet food products, and their health benefits are expected to be promising. Their range of applications is likely to expand even further in the future. By building on existing technologies, broader use of more diverse postbiotics may provide significant value in supporting pet health.

Why Postbiotics Matter in Pet Food

Today, most commercial pet foods are produced in one of the following two forms:

1. Dry products made by extrusion

2. Retort-processed products such as canned foods and pouches

These products can be stored at room temperature and often have a shelf life of around 18 months. However, because of the manufacturing and storage environment, probiotics, which are live microorganisms, are prone to die off, making it difficult to maintain their effectiveness.

Postbiotics, on the other hand, are promising ingredients that can solve this problem. Because they are not live bacteria but rather the metabolites or functional components produced by bacteria, they offer several advantages:

Thanks to these characteristics, postbiotics are attracting attention as ingredients that can contribute to health maintenance in future pet food development.

Compatibility with Minimally Processed Pet Food and Improved Shelf Life

In recent years, minimally processed pet foods, designed to preserve nutrients and palatability as much as possible, have also gained popularity. These products contain higher moisture levels and require refrigerated storage, but they are favored by health-conscious pet owners because they retain freshness and nutritional value well.

However, minimally processed foods tend to have a relatively short shelf life, often around six months, which presents a preservation challenge. Here again, the antimicrobial activity and acidic compounds associated with postbiotics may help improve shelf life.

For example, a 2019 study confirmed that lactic acid bacteria (LAB) can produce stabilizing compounds such as:

These compounds suppress spoilage organisms and pathogens through four main mechanisms:

In addition, bacteriocins produced by lactic acid bacteria can also contribute to improved preservation. For example, the following compounds are produced by strains of Lactococcus, Enterococcus, Pediococcus, and Lactobacillus, and they help enhance the safety of foods, particularly meat products:

Research Examples Demonstrating Health Benefits

Postbiotics not only improve shelf life, but also have beneficial effects on health, as shown in multiple studies.

Anti-Obesity Effects

Postbiotics have been shown to have anti-obesity effects. For example, a heat-treated, inactivated form of Lactobacillus reuteri isolated from canine saliva was administered to mice, and it was reported to suppress the normal age-related weight gain seen under ordinary conditions.

Improved Metabolism and Energy Utilization

Analysis of several postbiotic compounds, including SCFAs, has shown that they may promote thermogenesis and improve insulin sensitivity.

This is consistent with findings in dogs fed fermentable fiber, where increased levels of GLP-1 (glucagon-like peptide-1), a hormone that promotes insulin secretion, were associated with improved insulin sensitivity.

Suppression of Allergic Reactions and Immunomodulatory Effects

Attention has also been given to postbiotics derived from specific probiotics. For example, exopolysaccharides (EPS) derived from Bifidobacterium longum have been shown to suppress allergic reactions in the airways and lungs.

In addition, EPS obtained from several Lactobacillus strains have been reported to provide multiple health benefits, including immunomodulatory and antioxidant effects.

Future Outlook for Postbiotics in Pet Food Applications

Postbiotics are expected to attract even greater attention in the future as ingredients capable of overcoming the processing and storage challenges that are difficult to address with conventional probiotics.

In particular, they may be applied to a wide variety of products, including minimally processed pet foods, extruded dry foods, and various snacks and functional foods beyond retort products.

They are also especially promising in meat-based products, where the risks of spoilage and bacterial contamination are high. For example, their inhibitory effects against pathogens such as Salmonella make them highly attractive as a means of improving both safety and shelf life in pet food.

In this way, postbiotics represent a unique concept: they can provide health benefits even without being alive. This challenges the conventional assumptions surrounding probiotics.

Because of their excellent processing stability and scientifically supported range of health benefits, postbiotics are likely to become an important tool for product differentiation and value enhancement in future pet food development.